TM BOOK OF NEW THEULTIMATE COLLECTION OFTHEOCEAN’S MOSTSKILLED HUNTERS INSIDE:THELIFEOFTHEGREATWHITE Welcometo The deep dark blue harbours some of the...
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BOOK OF
THE ULTIMATE COLLECTION OF THE OCEAN’S MOST SKILLED HUNTERS
INSIDE: THE LIFE OF THE GRE
AT WHITE
Welcome to TM
BOOK OF
The deep dark blue harbours some of the most chilling and mysterious predators. Cunning, ruthless, and highly adapted to its environment, the shark is at the top of the ocean’s food chain, and continues to strike fear into the hearts of humans and animals alike. We go under the shimmery surface of the seven seas and dive deep into the world of these razortoothed creatures to discover the treasures they hide. Uncover the truth behind the monstrous face made notorious by Jaws, Deep Blue Sea, Sharknado and other high-action blockbusters. But there are more dangers lurking in these waters – get face to face with the jaws and claws that want to make you and other animals into their dinner, from cunning octopuses, humongous killer whales and yes, even fluffy grey seals.
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BOOK OF
Imagine Publishing Ltd Richmond House 33 Richmond Hill Bournemouth Dorset BH2 6EZ +44 (0) 1202 586200 Website: www.imagine-publishing.co.uk Twitter: @Books_Imagine Facebook: www.facebook.com/ImagineBookazines
Publishing Director Aaron Asadi Head of Design Ross Andrews Production Editor Sanne de Boer Senior Art Editor Greg Whitaker Designer Harriet Knight Cover images Alamy Printed by William Gibbons, 26 Planetary Road, Willenhall, West Midlands, WV13 3XT Distributed in the UK, Eire & the Rest of the World by: Marketforce, 5 Churchill Place, Canary Wharf, London, E14 5HU Tel 0203 148 3300 www.marketforce.co.uk Distributed in Australia by: Network Services (a division of Bauer Media Group), Level 21 Civic Tower, 66-68 Goulburn Street, Sydney, New South Wales 2000, Australia Tel +61 2 8667 528 Disclaimer The publisher cannot accept responsibility for any unsolicited material lost or damaged in the post. All text and layout is the copyright of Imagine Publishing Ltd. Nothing in this bookazine may be reproduced in whole or part without the written permission of the publisher. All copyrights are recognised and used specifically for the purpose of criticism and review. Although the bookazine has endeavoured to ensure all information is correct at time of print, prices and availability may change. This bookazine is fully independent and not affiliated in any way with the companies mentioned herein. World of Animals Book of Sharks & Ocean Predators © 2015 Imagine Publishing Ltd ISBN 978 1785461187
Part of the
bookazine series
Contents Sharks 10 The truth about sharks
86 Grey seals
16 50 facts about sharks
98 Galápagos sea lion
26 The most endangered sharks
90 Meet the family of whales
34 Tackling shark attacks
92 Songs of the humpback
38 All about great white sharks
98 Journey of the humpback
48 Great white attacks
100 Blue whales
54 Super senses of the hammerhead
102 The beauty of the gray whale
60 The beauty of the whale shark
104 Squid vs whale
62 Spotters’ guide to the whale shark
106 The mimic octopus
64 Prehistoric sharks
108 Meet the family of rays
66 Interview with Steve Backshall
110 Dolphins 118 Spotters’ guide to dolphins
Ocean Predators
120 Atlantic blue marlin
72 The mind of a killer whale
122 Saltwater crocodiles
80 18 facts about killer whales
134 Mysteries of the narwhal
82 The beauty of the orca
140 Polar bears
84 18 amazing facts about seals
150 50 facts about penguins
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© Thinkstock
Sharks They’re the surfer’s ultimate nightmare, their tailfin a horrifying omen of impending doom, but there is more to this razor-toothed killer than meets the eye 10 The truth about sharks 16 50 facts about sharks 26 The most endangered sharks 34 Tackling shark attacks 38 Great white sharks 48 Great white attacks 54 Super senses of the hammerhead 60 The beauty of the whale shark 62 Spotters’ guide to the whale shark 64 Prehistoric sharks 66 Interview with Steve Backshall
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© Dreamstime; Alamy
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Sharks & Ocean Predators
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The truth about sharks
THE TRUTH ABOUT Often the victims of fear and misinformation, the scientific facts about these killer fish are far more fascinating than any myth Legends of sea monsters were widespread in times before science was as advanced as it is today. Sailors would return from voyages and tell tales of mermaids, giant octopuses and enormous fish that attacked for sport. As time went on, our understanding of the sea grew and science eventually dispelled notions of such creatures, but revealed the truth about the ocean’s dangerous inhabitants.
Sharks haunt nightmares across the globe and their position in popular culture has been stirred by Hollywood hits like Jaws and media coverage of shark attacks. The truth about these huge fish is that they are intelligent animals at the very top of the food chain. Each has evolved to fill a specific niche and only a handful of these creatures can be considered truly deadly to humans.
What makes a fish deadly? Though a flounder is unlikely to strike fear into your heart, some fish have super-charged equipment to make them killing machines
Skin Even a shark’s skin is covered with teeth. These are called denticles and make the animal more streamlined.
Muscle Fast-twitch muscles allow sharks to leap high out of the water. The muscle contracts quickly for short bursts.
Senses Sharks have extremely good vision and smell to help pinpoint the exact location of their prey.
Teeth Growing up to 20,000 teeth in a lifetime, sharks constantly grow new teeth to replace any that are lost.
Electro-reception Jelly-filled pores on their face conduct electrical impulses, like those created by the muscles of injured prey.
Skeleton A shark’s skeleton is made of cartilage rather than bone, making the animal lighter, faster and more flexible.
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Sharks & Ocean Predators Mako shark
The fastest shark in the sea These sharks live out in the open ocean and hold two shark speed records. Not only have they been clocked at 32 kilometres (20 miles) per hour, but they also swim long distances at great speeds. Tagged sharks have been known to travel 2,130 kilometres (1,320 miles) in just 37 days, averaging almost 60 kilometres (40 miles) per day. Mako sharks can raise the temperature of their muscles to get them working faster. They also have a high metabolism that keeps them moving at all times of the day. Feeding on speedy fish like tuna has helped the mako develop its super speed. Bony fish make up around 90 per cent of a mako shark’s diet and the other ten per cent is a variety of foods, from squid to dolphins. Mako sharks are apex predators, which means they are at the top of their food chain. Without the threat from bigger carnivores, these sharks can focus all their attention and energy on hunting. Deep-water sharks are not usually a threat to humans, but the mako has been responsible for several attacks. Their speed, aggression and power make them one of the deadliest sharks on the planet.
What’s the rush?
Tail The asymmetrical tail is surrounded by muscle, making it a powerful engine that forces the shark forward. The shape makes the animal manoeuvrable and helps it change direction.
Mako sharks have evolved to swim at incredible speeds, partially to keep up with their fast-swimming prey
Muscle Most sharks have muscles along their sides, but mako shark muscles are closer to the spine. This gives them greater control over their tail, helping them launch out of the water.
Streamlining The torpedo-like shape slices through the water at break-neck speed. Their ridged skin cells help reduce water resistance and their fins keep them from rolling or spinning while swimming.
Lemon shark
The shark with the sharpest teeth Built to hunt, lemon sharks have several different strategies for catching prey. Swimming along the seabed, they disturb the sand to uncover buried fish before appearing from a swirling cloud of sediment in the ultimate surprise. Lemon sharks also ram feed, which involves lunging out of the water to snatch floating sea birds. Masters of the sea surface and the sand, lemon sharks have welldeveloped jaws to ensure prey has no chance of escape. Its jaws are controlled by a complex series of ligaments and muscles that control its stability. Surrounding joints prevent the jaws moving from side to side when the shark shakes its head vigorously with prey between its teeth. The jaw muscles are divided into four to act as a shock absorber when the mouth snaps shut and the split muscle helps deliver a greater force than one large block. The shape of the lemon shark’s teeth are the real danger and rather than being triangular, the teeth are long and pointed like miniature daggers. The pin-sharp tip of each tooth has a very small surface area, giving the teeth extreme pressure to pierce the skin.
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Lemon shark tooth
The truth about sharks Tiger shark
The ocean’s deadly genius Responsible for numerous attacks on humans, tiger sharks are definitely deadly. What makes them so dangerous is their intelligence, as they seem to understand the seasonal movements of their prey. Many shark species migrate and the tiger shark is no exception. In winter they flock to tropical waters, but explore more of the coastline as the water warms in summer. Travelling hundreds of miles, tiger sharks visit the same areas year on year to take advantage of different sources of food. The tiny and uninhabited French Frigate Shoals island chain in the middle of the Pacific Ocean is one of their frequent haunts. This area is populated by ground-nesting birds like albatrosses and tiger sharks are experts at snatching clumsy chicks that splash-land from their first flight. Australia’s Shark Bay is another popular tiger shark destination and other animals alter their movements to avoid becoming shark bait. Green turtles forage from the centre of lush sea grass fields in winter, but stick to the edges when sharks come along in the summer. Tiger sharks are one of the only animals to prey on adult turtles, so the turtles are constantly on the lookout for danger when sharks are in the bay. Dolphins and dugongs also make themselves scarce when the sharks are around.
Great white shark
The most feared creature on Earth A popular misconception is that great whites are aggressive and seek out humans to attack, but evidence suggests that sharks don’t go rogue or develop a taste for human flesh. Some believe that sharks mistake humans for sea lions, their favourite prey animals, but this is not the case either. When a shark attacks a sea lion it zooms to the surface and bites down with extreme force. It’s typical for a great white shark to approach a human at a leisurely pace and take a bite or two. Sharks use their teeth like we use our hands and biting an unfamiliar object is a great white’s way of trying to understand what the object is. They are extremely curious and investigative animals. When the mouth is open, the tooth bed is pulled back and the teeth flex outward by ten to 15 degrees. This allows the jaws to act like a pair of forceps and inspect what’s in the fish’s mouth. Sea lions are coated with insulating fat, which provides a great white with twice the energy as ingesting muscle. When a shark gets hold of a human, it realises the contents in its mouth are bony and full of muscle and often lets go. Unfortunately, at this point the damage is already done.
“ When a shark gets hold of a human, it realises the contents in its mouth are bony and full of muscle and often lets go” GREAT WHITE SHARK Carcharodon carcharias Class Chondrichthyes
Territory Temperate seas Diet Marine mammals and fish Lifespan Up to 70 years Adult weight 2,300kg (5,070lb) Conservation status
VULNERABLE
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Sharks & Ocean Predators Bull shark
The deadliest shark alive With the ability to invade fresh water as well as the ocean, bull sharks have evolved to handle environments that other sharks cannot. It gets its name from its strength, stockiness and ferocious reputation. This species has been spotted 4,000 kilometres (2,485 miles) up the Amazon river, as well as in rivers across the globe. Its kidneys have evolved to process both salt and fresh water to give it more water to explore. It is well documented that bull sharks have eaten other members of their own species, along with smaller sharks and bony fishes. They swim slowly along the seabed, stalking their target before launching toward it with its jaws wide open. Its teeth are heavily serrated and tear through flesh with ease. The small eyes indicate the fish relies more on electro-reception than its vision and therefore might be more likely to attack an unfamiliar animal. Many attacks on humans have been reported, with one expert suffering a bite during a television interview. Though they aren’t the biggest, these sharks can pop up in almost any body of water and attack anything that’s swimming. They have a big appetite and don’t share the great white’s particular taste when it comes to what they eat.
“ Many attacks on humans have been reported, with one expert suffering a bite during a television interview”
Megalodon myth
© Frank Lane Picture Agency; Alamy; Thinkstock
Though long extinct, reports of megalodon sightings keep the world guessing Don’t be fooled by altered photographs or misleading footage. The largest shark that ever lived is extinct and has never been seen alive by human eyes. Measuring up to 18 metres (59 feet), the shark’s size has been determined by its large teeth and rare fossilised sections of the shark’s spine. If the giant shark still existed it would need a healthy supply of extremely large animals like whales to survive. However, It is thought that the megalodon’s extinction allowed the evolution of large filter-feeding whales. If the megalodon still existed, whales probably would not.
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Megalodon
“The largest shark that ever lived is extinct and has never been seen alive by human eyes”
Whale shark
Great white shark
20m (65.6ft)
The truth about sharks BULL SHARK Carcharhinus leucas Class Chondrichthyes
Territory Coasts of the southern hemisphere Diet Fish, marine mammals Lifespan Up to 16 years Adult weight 90-230kg (198507lb) Conservation status
NEAR THREATENED
Four myths about sharks Some fallacies about the oceans’ greatest hunters All sharks are man-eaters While some species do indeed have an occasional nibble on unfortunate humans (the great whites, bull and tiger variety being among them), that leaves approximately 475 types of sharks that don’t.
Sharks need to keep moving in order to survive It’s true to a certain extent that some sharks need to move in order to breathe as they need water flowing over their gills to take in oxygen, but the vast majority are able to pump water over their gills. This means they can remain more or less stationary in the water and still “breathe”.
Buccal chamber Sharks maintain a flow of water to their gills by expanding and contracting a cavity in their head called the buccal chamber.
Mouth open Valves leaving the gills stay closed and water rushes in to the buccal chamber causing it to expand.
Sharks have to turn on their side to bite properly
Sharks can smell human blood from miles away
Sharks are adept at biting and certainly don’t have to be sideways in order to do so. The misconception could come from the fact that they whip their prey around to break off chunks of meat.
They can smell food, but if their sense of smell were so sensitive as to detect human blood from miles away, the other smells throughout the ocean would be overwhelming.
“Sharks are adept at biting and certainly don’t need to be sideways in order to do so”
Mouth closed The valves are open, so the buccal chamber contracts and forces water through the gills.
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Sharks & Ocean Predators
50 incredible facts about the planet’s most extreme underwater predator Nearly every stereotype of the shark is wrong. They aren’t primitive animals, they aren’t mindless killing machines and they don’t prey on humans. Sharks are elasmobranchs, meaning that they are fish with cartilage skeletons instead of bones. Far from being an evolutionary leftover, however, this evolved to save weight so large sharks could still be fast and agile swimmers. Cartilage also lets sharks conserve calcium and phosphorous, which is important because they need both for making teeth. And they get through a lot of those. Sharks treat their teeth as disposable weapons and can lose a couple with every bite. In fact, sharks go through so many teeth in their lifetime that the availability of the mineral phosphorous was historically the biggest constraint on their spread around the world.
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Sharks haven’t always been objects of fear. Victorian sailors regarded them as entirely benign – like dolphins. Then in 1916, along the coast of New Jersey, four people were killed and one badly injured in a spate of unprovoked attacks by sharks. This sparked a media frenzy that inspired the famous 1974 novel Jaws by Peter Benchley, and its even more famous movie adaptation, and sharks have been the villains of the sea ever since. Despite the fact that you are roughly twice as likely to die from a coconut landing on your head than a shark bite, we still have a grossly inflated sense of the threat these creatures pose. Sharks are apex predators and very well adapted for hunting in the sea, but the fact remains that for every human eaten by a shark, 20 million sharks are eaten by humans.
50 facts about sharks
© Thinkstock
“Sharks treat their teeth as disposable weapons and can lose a couple with every bite”
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Sharks & Ocean Predators
Shark bites Do sharks have 1of taste? tongues and a sense The basihyal looks a bit like a tongue, but it is really just a protrusion of cartilage on the floor of the mouth. Sharkshave tastebuds on the rest of their m outh, though, and often give prey a test bite to check the flavour.
Shark anatomy
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What’s inside a shark? Cloaca Combined opening for excretion, defecation and reproduction. Males have clasper fins instead of a penis.
Spine Made of cartilage rather than bone. It extends into the top tail fin, for extra power.
Nostrils Used for smelling, not breathing. Some sharks have protrusions called nasal barbels that act as smelling probes. First dorsal fin Spine
Second dorsal fin
can you tell a 2 How shark’s gender?
Caudal fin
©
Male sharks have a pair of protrusions called claspers on their belly, between the pelvic fins. These are used like a penis to insert into the female’s cloaca.
DK Im ag es
Upper lobe
Pelvic fin
Stomach Very large compared to the intestine and can stretch to cope with large meals. Pectoral fin
Corkscrew valve Slows down food through the very short intestine, to give enough time to digest it.
Liver Full of dense squalene oil, the liver can comprise up to 30 per cent of the shark’s mass and take up as much as 90 per cent of the space in the body.
© Jlencion
Lower lobe
Epigonal Unique to sharks. It is thought to help with making red blood cells, since sharks have no bone marrow.
Heart Sharks have much lower blood pressure than us. Swimming muscles assist the weak heart.
do 3 How sharks hear?
The basihyal looks a bit like a tongue, but it is really just a protrusion of cartilage on the floor of the mouth. Sharkshave tastebuds on the rest of their mouth, though, and often give prey a test bite to check the flavour.
do you tell the 4 How age of a shark?
It’s not easy. Because they shed their teeth so often, you can’t measure the growth rings in them to determine age. The vertebrae have growth rings too, but they aren’t added at a uniform rate, so researchers inject marker chemicals to captured sharks to provide reference samples.
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© Thinkstock
“Sharks treat their teeth as disposable weapons and can lose a couple with every bite”
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Why do sharks have so many fins?
They don’t really have many more fins than other fish, it’s just that they are larger and more conspicuous. Sharks use their wide pectoral fins to generate lift, like the wings of a plane. The tail, or caudal fin, has a larger upper lobe because the spine extends into it. This generates thrust and the notches reduce turbulence. The dorsal and anal fins reduce the amount of side-to-side motion as the tail beats. The second dorsal fin is the only one missing from other fish and it offsets the movement of the large upper caudal lobe.
© Thinkstock
50 facts about sharks
It’s essential that sharks keep moving in order to get enough water across their gills to breathe, find out more about shark respiration below…
Gill septum
Gill arch
2. Gill slits It passes over the gill bars and exits through the gill slits.
4. Spiracle Bottom-dwelling sharks have an opening behind the eye that can pump water over the gills when the shark isn’t moving.
1. Inhale Water enters through the mouth, driven by the forward motion of the shark.
Capillaries Oxygen-depleted water Gill filaments
Oxygen-rich water
Gill arches Ventral aorta
8 How many teeth does 3. Passive ventilation Open-water species need to keep swimming anyway or they will sink, so this system works fine.
“A greatwhite shark can get through up to 50,000 teeth in its life”
© DK Images
a shark get through in a lifetime? Why is this number so high? Shark teeth aren’t embedded in the jaw, but attached to the skin. They are designed to be disposable and are continually replaced like a conveyor belt from the back of the mouth. A great white shark can get through up to 50,000 teeth in its lifetime.
Growth Layers of razor-sharp, serrated teeth roll forward to replace broken or missing ones.
No. Sharks belong to the elasmobranch group of fish that have lighter, more flexible cartilage in their skeleton, instead of bone. Their muscles are anchored directly to the inside of their tough skin.
do sharks 10 How stay buoyant?
5. Gulping Some species also use the mouth to actively gulp water across the gills.
Heart
Shark bites sharks have 9 Do bones like dolphins?
Sharks don’t have a swim bladder like other fish, so they use their liver instead. The amount of squalene oil stored there is adjusted to leave the shark slightly heavier than water. The extra buoyancy is supplied by dynamic lift from the shark’s fins as it swims
good is a 11 How shark’s eyesight?
Sharks have good night vision and can contract and dilate their pupils, which bony fish can’t. Sharks are either colourblind or can see only shades of grey and green, depending on the type of shark.
Does a shark’s 12 skin help it to swim faster? Shark skin is covered with scales like other fish, but shark scales are made from dentine and actually resemble tiny teeth more than scales. These ‘dermal denticles’ generate tiny vortices on their trailing edges as the shark swims and this vastly reduces the shark’s drag through the water.
The huge jaws of a prehistoric shark, the megalodon
© Getty
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If a shark stops swimming does it drown?
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Sharks & Ocean Predators
Shark bites long do 13 How sharks live?
Megalodon
Snout Megalodon ate whales, so its snout was shorter to let it bite into large prey.
Most species live for between 20 and 30 years. But the whale shark is estimated to live for up to 100 years.
the 14 What’s smallest shark?
A kind of deepwater dogfish shark called etmopterus perryi. It lives in the Caribbean Sea and grows no larger than 20cm (7.8in) – a real puppy of a shark.
any sharks 15 Do glow in the dark?
Yes, a few species use bioluminescence to lure prey. The brightest is the cookie cutter shark, which glows over its entire stomach, except for a dark band round its neck. This makes it look like a much smaller fish silhouetted against the sky.
it true sharks 16 Isdon’t get cancer?
Sharks definitely do get cancer, but there’s some evidence that a compound called angiogenin, an inhibitor in shark cartilage, reduces the ability of tumours to grow, but scientists haven’t yet agreed on this. The disease can still be fatal for sharks.
What’s the most 17 endangered species of shark? Both the large sawfish and the common sawfish are listed as critically endangered by the International Union for Conservation of Nature. Their saw snouts can easily become entangled in fishing nets, and they become trapped.
Great white Size Megalodon was probably 12-20m (39-66) long. That’s larger than a modern whale shark.
Bones Although megalodon didn’t have true bones, its skeleton was much more calcified than modern sharks.
19 Was
megalodon a real shark? Megalodon is an extinct species that lived between 28 and 1.5 million years ago. Only teeth fossils and a handful of isolated vertebrae have ever been found, so most of what we know about this animal is extrapolated from comparisons with living sharks. It does seem to have been a true shark – probably related to the great white and mako sharks. But it was much bigger – between 2.5 and 3 times the size of a great white.
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Jaw Calculations suggest that megalodon had a bite five times more powerful than that of a tyrannosaurus rex.
20 How many shark species are there?
True sharks are classified in the superorder selachimorpha and there are more than 440 species alive today. A new species of shark, skate or ray is identified approximately every two weeks or so.
How do sharks give birth, and what are ‘mermaid’s purses’? Some sharks lay eggs inside a case
Which is 18 the fastest shark ever to have existed? The shortfin mako shark is commonly thought to be the fastest shark ever. An openwater hunter that chases fast fish such as tuna, it can reach up to 32km/h (20mph). © Alice Wiegand
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Teeth 18cm (7in) long and very robust. Edges were lined with very fine serrations.
Most sharks retain their eggs inside the female and give birth to live young, unlike other fish that commonly lay their eggs. A few species, including the horn shark and Port Jackson shark lay eggs inside a leathery egg case. Empty egg cases that wash up on the shore are called mermaid’s purses, for imaginative reasons.
50 facts about sharks
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How does a hammerhead shark know which way it’s going?
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Which ones don’t look like sharks? Stingray
Not properly. Some species rest on the seabed, but their eyes will still follow nearby swimmers. Others may rest one half of their brain at a time, like dolphins do. The spiny dogfish uses its spine to co-ordinate swimming, so that it can rest its entire brain without stopping.
Are sharks 28 solitary or do they live in groups?
© Jeremy Collins
Despite their oddly shaped heads, hammerhead sharks can see forwards at least as well as other sharks, and possibly better. All fish have their eyes set on the sides of their head, but the hammer or cephalofoil on a hammerhead shark is right at the front so they have much less snout to get in the way of forward vision than other sharks. The wide separation also allows better directionality of the special electrical sense of sharks. Hammerheads eat stingrays and their electrical sense helps them find rays buried under the sand on the seabed.
Shark bites 27 Do sharks sleep?
Electric ray
Many species are highly social. Scalloped hammerheads can form schools of up to 100 sharks, for example. Even the normally solitary hunting species can congregate in groups around a rich food source or to breed.
Do sharks ever 29 attack/prey on other shark species?
© Brocken Inaglory
24 What is the deadliest shark? The International Shark Attack File keeps records going back to the 16th century and shows that the tiger, bull and great white between them account for 99 per cent of shark attacks on humans. Of these, the great white tops the list with 249 unprovoked attacks and 65 fatalities.
the oldest shark on record? Modern sharks date back 100 million years, but there were primitive sharks as long ago as 420 million years. One of the earliest was cladoselache, from around 370 million years ago. Well preserved fossils show skin, muscles and even internal organs. Apart from a few around the mouth and fins, cladoselache had no scales. Its teeth were smooth and it swallowed its prey whole.
© Bathynome
25 What’s
Skate
Frilled shark
© OpenCage
What’s the biggest shark?
it have 30 Does natural enemies? While the shark is high up the food chain, orcas have been known to attack and kill great white sharks, and sperm whales are also occasionally believed to kill sharks. These are exceptions, though. Most of the time, sharks sit firmly at the top of the food chain.
Manta ray
© Moesmand
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Carpet shark
© Richard Ling
The whale shark. As well as being the largest shark, this is also the largest fish. Only true whales are larger. Adults can be over 20m (66ft).
Most shark species have fairly specific diets – blue sharks mainly eat squid, for example. But great whites, tiger sharks and mako sharks will eat tuna, seals, sea lions, dolphins and even smaller shark species. Hammerhead sharks dine almost exclusively on rays, which are closely related to sharks.
Sawfish
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Sharks & Ocean Predators
Shark bites How many 31 people are killed/ attacked by sharks every year? In the last ten years, the number of fatalities caused by sharks averages out at less than five per year, worldwide.
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How powerful are shark jaws?
Razor The mako shark’s front teeth are razor sharp and are backward orientated to aid grip. Wear and tear Due to their thinness, the mako’s teeth are continuously worn down and replaced constantly.
A six-metre shark, such as a great white, can exert more than 18,000 newtons of force with a bite. That’s a huge force – twice as much as the largest alligators, which have the strongest bite of any land animal, and more even than current estimates of the bite of the T-rex. But it doesn’t end there. An alligator only exerts maximum bite force when its jaws are almost shut. The wider it opens its mouth, the less leverage is available for the jaw muscles and the weaker the bite becomes. Great white sharks have a unique arrangement of muscles in their jaw that enables them to exert maximum bite force, regardless of how wide their mouth is opened.
How many 32 sharks are killed/ attacked by people every year? About 100 million sharks are killed every year by humans. Some of this is recreational fishing, but most is commercial. Sharks are killed for their fins for shark fin soup, and in the Australian state of Victoria, shark is the most commonly used fish in fish and chip shops.
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If you turn a 33 shark upside down does it go into a
Force The wider the mako opens its mouth the less bite force it has. As such, it relies more on cutting its prey, rather than crushing it.
deep trance?
34
© Science Photo Library
This is called ‘tonic immobility’ and it doesn’t work with all species, but yes, lemon, nurse and bull sharks and even great whites will suddenly become paralysed when flipped on their back. This may have evolved as part of mating, to protect females from aggressive males.
How fast can a shark swim?
Sharks contract the muscles on their left and right sides alternately to drive their large tails sideways. This makes the head move side to side. Their rigid skin and drag-reducing dermal denticles allow them to reach speeds of up to 32km/h (20mph).
How smart are sharks?
Everyone know dolphins are intelligent, but what about sharks? Sharks have a similar ratio of brain to body mass as most mammals and birds. They certainly aren’t mindless killing machines. Seven great white sharks were observed in 1987 off the coast of South Africa, co-operating to refloat a dead, beached whale so that they could eat it. When great whites hunt dolphins, they approach from above and behind, to prevent the dolphin using its echolocation sense to detect the shark.
“There were primitive sharks as long ago as 420 million years”
37 Do sharks use
Ampullae of Lorenzini These jelly-filled sacs in the head help the shark locate prey.
© Stormy dog
electricity to sense their prey?
22
Sharks have an arrangement of jelly-filled pores, concentrated around the head. These are called ampullae of Lorenzini and they allow the shark to detect electromagnetic fields. As well as giving sharks an internal compass, this lets them detect the minute electrical fields produced by the muscle contractions of all living animals. A few fish and other animals can also sense electrical fields, but sharks have by far the most sensitive version of this sixth sense.
Electro cells The sensory cells in the snout detect electrical signals in the water.
50 facts about sharks
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Statistically, what are the most deadly places on Earth with regard to shark attacks? USA Native example: Basking shark (cetorhinus maximus) Total attacks: 947 Fatal attacks: 36 Last fatality: 2010
BERMUDA Native example: Silky shark (carcharhinus falciformis) Total attacks: 3 Fatal attacks: 0 Last fatality: N/A
EUROPE Native example: Porbeagle (lamna nasus) Total attacks: 36 Fatal attacks: 17 Last fatality: 1984
Thresher shark
Basking sharks are huge but generally harmless
ASIA Native example: Oceanic whitetip shark (carcharhinus longimanus) Total attacks: 120 Fatal attacks: 52 Last fatality: 2000
Bull shark Basking shark Shortfin mako
Hammerhead Whale shark
Whale shark
Great white Nurse shark
Tiger shark
PACIFIC/OCEANIA ISLANDS Native example: Tiger shark (galeocerdo cuvier) Total attacks: 121 Fatal attacks: 48 Last fatality: 2009
ANTILLES/BAHAMAS Native example: Blacktip shark (carcharhinus limbatus) Total attacks: 61 Fatal attacks: 15 Last fatality: 1972
SOUTH AMERICA Native example: Bignose shark (carcharhinus altimus) Total attacks: 101 Fatal attacks: 23 Last fatality: 2006
OPEN OCEAN Native example: Dusky shark (carcharhinus obscurus) Total attacks: 17 Fatal attacks: 5 Last fatality: 2006
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Are there sharks living in every ocean on the planet? Yes. Sharks can cope with a wide range of ocean temperatures, even within the same species. Some sharks migrate thousands of miles each year.
AFRICA Native example: Bull shark (carcharhinus leucas) Total attacks: 299 Fatal attacks: 78 Last fatality: 2010
AUSTRALIA Native example: Scalloped hammerhead (sphyrna lewini) Total attacks: 417 Fatal attacks: 131 Last fatality: 2010
CENTRAL AMERICA Native example: Great white shark (carcharodon carcharias) Total attacks: 52 Fatal attacks: 26 Last fatality: 2008
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What’s a common shark in British waters? Most of the small shark species seen off the British coast are referred to collectively as dogfish. This includes the spotted dogfish and the spiny dogfish. They can reach 1-1.5m (3.3-4.9ft) in length.
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Is there such a thing as a freshwater shark? No shark species spends all its time in fresh water, but both the river shark and bull shark have adapted kidneys that allow them to cope with fresh water for extended periods. They can swim hundreds of miles up large rivers in search of prey.
NEW ZEALAND Native example: Blue shark (prionace glauca) Total attacks: 44 Fatal attacks: 8 Last fatality: 1968
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Where can I find sharks?
BASKING SHARK: temperate waters, both coastal and offshore BULL SHARK: shallow tropical coastal waters, estuaries and large rivers GREAT WHITE: coastal and offshore temperate waters worldwide HAMMERHEAD: temperate and subtropical waters on the continental shelf NURSE SHARK: shallow tropical reefs off the coast of West Africa and Central America SHORTFIN MAKO: offshore tropical and temperate waters worldwide TIGER SHARK: tropical and subtropical deep water around reefs THRESHER SHARK: tropical and temperate waters on the continental shelf of North America and Asia WHALE SHARK: offshore tropical and subtropical water, especially the west coast of Australia
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© NASA
HAWAII Native example: Sandbar shark (carcharhinus plumbeus) Total attacks: 102 Fatal attacks: 8 Last fatality: 2004
Sharks & Ocean Predators
43 Can sharks smell
IC;BBIEC;J>?D=O5 Sharks have an incredible sense of smell, and can tell which direction a smell comes from with their separate nostrils.
blood from miles away, and if so how? The open-water species can detect blood at concentrations as low as one part per million, but they are even more attracted to the smell of fish guts. By comparing the timing of the scent’s arrival at each nostril, they can tell its direction and quickly home in on distant prey.
© Science Photo Library
Eyelid The eyes roll back in their sockets before the shark strikes.
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How do sharks attack?
Only a few species of shark are solitary ambush predators – many are filter feeders or eat small fish and crustaceans on the seabed. The aggressive hunters – tiger shark, bull shark and great white – usually patrol close to the surface. They attack at dawn or dusk, when light is poor, and from above so their light-coloured bellies make them hard to spot against the sky. Some species of shark have an extra transparent eyelid (called a nictitating membrane) that can shield their eyes, but the great white does not, so it rolls its eyes back in their sockets just before its strike connects, to protect them. Very often sharks will pursue a hit-and-run technique, taking a single bite out of their prey and then retreating to allow it to bleed to death.
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weirdest items found in a shark?
© Science Photo Library
Great white sharks roll their eyes when they attack
45 What are the
BWZ_[iÊfo`WcWi 7hkXX[hjoh[ 7hebbe\Y^_Ya[dm_h[ JWhfWf[h 7XW]e\fejWje[i EZZi^e[i 7Ze] 7YWde\IfWc 7iWYae\YeWb J^[^[WZWdZ\eh[gkWhj[hie\W YheYeZ_b[ (All found in the stomachs of tiger sharks, which are the most indiscriminate feeders.)
50 facts about sharks
INTERVIEW Richard Peirce
How It Works spoke to Richard Peirce, chairman of the Shark Trust, about sharks, their behaviour around humans and how many species are becoming increasingly endangered.
WHAT’S IN A NAME The tiger shark is named aer the sand-coloured stripes on the sides of juvenile tiger sharks, which fade over time.
The Trust was founded in 1997 and it was set up to advance the profile of all families of sharks through awareness, education, legislation and policy. In recent years we have become accepted as the first stop for government departments wanting to look at fisheries legislation.
Which sharks 47 are native to the UK and are media claims of danger overblown?
TALKING TRASH The tiger shark is a potty mouth in the sense that it will eat almost anything, earning him the nickname “wastebasket of the sea”.
My book, Sharks In British Seas, lists the 30 or so species that inhabit our native waters. There are many top-of-the-range and iconic species close to home. For example, the hammerhead is a British species; the same can be said for threshers, makos and blue sharks. A favourite of mine is also native: the porbeagle, which is a genuine mini great white… and often mistaken as one. On the area of danger to the public… there has never been a single recorded shark attack in British waters in the conventional sense. There have been shark-caused deaths and incidents, but there has been nothing like we have tragically seen in the Seychelles recently, despite us having some sharks that people would consider dangerous to man.
Does a shark 48 behave differently in the
presence of humans?
“Often sharks pursue a hit-an-run technique, taking a single bite out of a prey and letting it bleed to death”
It differs mainly from species to species and circumstance. If you are a diver on air and just chilling
out, diving along a reef, that is completely different from being with a shark in a baited situation where its feeding senses have been stimulated. So if you are chumming for sharks – a process where you put an attractant into the water to generate a scent corridor – and in a cage then they behave very differently.
is cage 49 What diving about?
Cage diving is a fantastic way to see sharks… The cage has a hinged top that rests on the surface of the water. So the human jumps over the side of the boat and into the cage… They then proceed to move to the bottom of the cage, which is commonly about nine feet in depth. So the top of their head is usually only about three feet below the surface of the water… There is a rope out with some bait on it and the shark is drawn to that. The bait line is then drawn towards the cage and the shark will follow it. The boat’s operator will then say something like ‘coming in from the left’, and the cage’s occupant will then take a big draw of breath and submerge themselves for ten seconds or so, viewing the shark as it passes.
Where is the best place to 50 go cage diving? I would say South Africa. It isn’t necessarily the place with the clearest waters, but it is affordable and it is pretty commercialised, with companies running multiple dives a day. You can do it off Britain, though; I helped set up Atlantic Divers in Newquay, Cornwall..
© Thinkstock
What activities 46 does the Shark Trust undertake?
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Sharks & Ocean Predators
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Endangered sharks
ENDANGERED SHARKS Often unmatched in their own ecosystem, the ocean’s most feared apex predators are threatened by human activities, from unregulated fishing to habitat degradation Sharks are without doubt one of the most iconic animals on our planet. From their hunting prowess to their swimming speed, sharks are an unparalleled example of evolution’s ability to produce a truly incredible beast. Although few sharks are preyed upon in the ocean, many have become endangered due to increased human activity over recent decades. A number of different threats affect each shark species, from general hunting to habitat degradation and food chain alteration. Many experts agree that the biggest problem over the years has been unmanaged fisheries, which are still a significant threat in some parts of the world. This has enabled sharks to be fished at an unsustainable rate, with companies looking to maximise profits without consideration for the welfare of a certain shark species. Catching sharks by accident (something known as ‘bycatch’) is also a serious issue; many are just tossed back overboard as they are no use to the fisherman, often already dead or seriously injured. The issue of shark finning is well documented, which often involves catching the shark, removing its fin and putting it back in the water, even though it cannot survive this ordeal. The fin is then used to make shark fin soup, which is still incredibly popular in China where it’s seen as a delicacy to be served at special occasions such as weddings or banquets. Their meat is also highly sought after in parts of the world, as is their cartilage, which is used medicinally, mainly in Asia. The trade of trinkets that include shark teeth and even jawbones continues to flourish internationally, and is another reason why sharks are still being caught and killed in such large numbers.
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Sharks & Ocean Predators
Basking shark
This huge shark is equipped with an extremely wide jaw and large gill slits, but is no threat to humans
Basking sharks are truly incredible creatures that use more than 1,500 gill rakers to strain plankton from roughly 1.5 million litres (330,000 gallons) of water per hour. They are the second largest fish species, growing to 10 metres (33 feet) in length. An adult basking shark’s liver can weigh around one tonne (157 stone), making up a quarter of its total body weight. It can live to the grand old age of 100 in the wild. These sharks have unfortunately been hunted in large numbers for their fins, liver, flesh and skin. They are also vulnerable to attack from killer whales and tiger sharks, as an adult basking shark can provide a hugely nutritious meal for either of these two predators. However, a decline in basking shark numbers is mainly down to human hunting. Their cartilage is still used today in Chinese medicine and as an aphrodisiac in Japan.
Dusky shark Threatened by humans and eaten by other sharks, the dusky shark’s population has dramatically dwindled Found in tropical and temperate waters, the dusky shark can reach lengths of 4.27 metres (14 feet) and a weight of 180 kilograms (400 pounds). Each year dusky sharks embark on a voyage known to exceed 3,700 kilometres (2,000 miles), as they swim towards the Poles in the summer before returning to Equatorial waters for the winter months. An unusual fact about the dusky shark is that it takes 20 years for it to reach sexual maturity, something that has made the recovery of their struggling population almost impossible, as it has one of the lowest reproductive potentials of any shark in existence. Their population has dropped to between 15 and 20 per cent of the figure from 1970, due to the continued shark fin soup trade and because they often die after being accidentally caught by fisherman. Scientists believe it could take up to 400 years for their population to recover.
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Endangered sharks The great white’s monstorous looks don’t help when it comes to conservation
Great white This great hunter is equipped with six senses and rows of sharp teeth They may be capable of sensing a drop of blood in 100 litres (25 gallons) of water and even smaller amounts within a five kilometre (three mile) radius, but the great white is responsible for less than half of all shark attacks each year, few of which are fatal. They are designed for
predation, able to reach speeds of 24 kilometres (15 miles) per hour with ease. Once they catch up with their prey, their 300 odd teeth make quick work of the kill. Although the great white is feared by many around the world, it is no less susceptible to hunting by humans. Their
teeth and jaws are a particularly popular trading item, and their meat is often sold for the manufacture of pills in Asia. At one point there were thought to only be 3,500 great whites left in the wild, but there have been signs of population growth off the coast of California. Despite its size, the whale shark doesn’t hunt big prey – quite the opposite in fact
Whale shark
The largest living species of fish in the world, the whale shark can grow to an impressive 12 metres (39 feet) or more At 18.7 tonnes (2,944 stone), the whale shark chooses to satisfy its massive appetite with plankton. Swimming close to the surface they open their formidable jaws and scoop up these tiny plants and animals, along with anything else in their path. The whale shark is a filter
feeder much like the basking shark. Their fearsome size somewhat belies their nature, as they are known for being incredibly docile fish, sometimes allowing swimmers to hitch a ride on their backs. In spite of being listed as a vulnerable species, they continue to be hunted
in parts of Asia, particularly the Philippines, even though the fishing, selling and exportation of whale sharks was banned back in 1998. The 2010 oil spill in the Gulf of Mexico is thought to have affected the population, as the oil lingered near the surface where they feed.
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Sharks & Ocean Predators
The scalloped hammerhead shark
The oddly shaped heads of these amazing sharks actually improves their ability to find prey
Famed for its mallet-shaped head, the scalloped hammerhead’s unusual appearance functions to spread out its specialised sensory organs, which they use to scan the ocean floor for food. This helps them to seek out their favourite meal, a stingray, as it provides them with excellent sensitivity to electrical fields, so it can detect a potential meal even when
it’s completely buried in sand. Living at depths of up to 500 metres (1,600 feet), scalloped hammerheads roam the seas in vast schools, to help keep reproduction high and as part of their feeding habit. Hammerhead sharks are unfortunately among the most commonly caught sharks for finning, which has caused its population to decline by up to 95 percent during the past 30 years. It is unknown how many remain in the wild.
Angel shark This ambush predator can pump water through its own gills, so that it can keep breathing while lying in wait for its prey Angel sharks can easily be mistaken for rays or skates, due to their unusual flattened body and broad pectoral fins, and because they spend most of their days buried in the seabed with only their eyes visible. They use this position to hide from their prey, sometimes waiting up to a week before pouncing on a
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suitable meal. Many shark species need to swim in order to breathe, but the angel shark is able to breathe while remaining motionless thanks to the spiracles on top of its head. These structures pump water through the gills, providing a continuous supply of oxygen. Until the late 1970s the angel shark had
no commercial value but suddenly began to be marketed, causing the annual catch rate to rise from 147 kilograms (324 pounds) in 1977 to the equivalent of a staggering 90,000 angel sharks in 1985, from central California alone. By 2010, the angel shark was classified as critically endangered.
Endangered sharks
Gulper shark This rare deep water dogfish is found only off the coasts of Australia and New Zealand Known as the dumb gulper or Harrison’s dogfish, this shark grows to just over a metre (3.3 feet) in length and has a large mouth, a long, flattened snout and huge, distinctive green eyes. It is known to live near the seabed, at depths
of up to 790 metres (2,592 feet), where it feeds on small fish. For such a small shark its lifespan is impressive; closely monitored adults are known to have lived for at least 46 years. The population of dumb gulpers is suffering, partly due to
their low reproductive rate; as soon as this was accompanied by heavy trawl fishing and drop-lining, the numbers began to plummet, leaving the species in serious peril today.
Zebra shark These zebras can change their stripes; once they reach adulthood they switch to spots Confusion over what to call the zebra shark is unsurprising, considering it has the characteristic stripes of its four-legged, African namesake during its youth before the spots most famously sported by leopards develop on their skin. The zebra shark has two more distinguishing features, its huge tail that is nearly the same length as its body, and the prominent ridges that run along the entirety of the shark. They feed mainly on molluscs and crustaceans; their flexible body allows them to squeeze into the narrow crevices where these creatures are often lurking. Unfortunately, zebra sharks are frequently hunted, both for sport and commercially for their fins, flesh and liver oil. The degradation of coral reefs is also bad news for this species, as this forms much of their natural habitat.
“Their flexible body allows them to squeeze into the narrow crevices where these creatures are often lurking” 31
Sharks & Ocean Predators
Speartooth shark
Rarely seen by humans, the speartooth shark unusually inhabits tropical rivers and estuaries Few sharks are as elusive as the speartooth. Unlike most other species of shark, it uses tidal currents to aid its movement in water; flooding tides carry it upstream while ebbing tides return the speartooth back downstream. They prey mainly on small, bony fish and crustaceans at night, and are perfectly adapted to hunting in almost complete darkness. This is thanks to their small eyes and abundant ampullae (electroreceptors). Speartooths are threatened by mainly unregulated fishing and habitat degradation. Speartooths are also facing drastic habitat modification, as dredging and mining damage the ecosystem in which they live. There are thought to be no more than 2,500 in the wild, although this is only an estimate.
This rather comic looking shark is capable of some incredible things in order to survive
Porbeagle shark Often referred to as blue dogs or mackerel sharks, the porbeagle can raise its body temperature to 10oC (50oF) above the surrounding water This shark’s ability to change its body temperature is vital, allowing it to adapt to the variable temperatures of the North Atlantic Sea. This is achieved through a process called thermoregulation, and helps the shark to swim faster when hunting for prey. Although the porbeagle is most commonly seen in the North Atlantic it can be found all over the world, including South African and Australian waters. The shark’s most distinctive feature is its jagged, three-cusped teeth, but it can also be identified by a white blotch on its first dorsal fin. Aggressive fishing in Norway and other areas has caused porbeagle numbers to drop – they are often caught by accident and then often die as a result. Like the gulper shark, they have a low reproductive rate, which has unfortunately led them to become an endangered species.
“The shark’s distinctive feature is its jagged, three-cusped teeth” 32
Endangered sharks
SHARK ALERT!
Shark populations continue to decline at an alarming rate
AN ESTIMATED
32%
SOME SHARK
POPULATIONS HAVE DECREASED BY
OF OPEN OCEAN SHARKS
ARE THREATENED WITH EXTINCTION
99%
Percent of Historic Populations
OVER THE LAST 100 89%
79%
65%
up to
83%
80%
60%
5%
70%
75
50
50
YEARS
25
0
Hammerheads
White Shark
Tiger Grey Thresher Blue Mako Shark Shark Shark Shark Shark
Oceanic Whitetip
Interview with shark expert – Paul Cox We spoke to the Shark Trust’s Director, Paul Cox, to find out how they are trying to save sharks What are the main things that the Shark Trust are trying to implement at the moment? We have a three-pronged approach. We are firstly looking at science-based, sustainably managed fisheries. We work at policy level with the fishing industry and with the public to try to keep up the pressure and ensure that where sharks are being caught, they are part of a managed, sustainable fishery. Linked to that, we are increasingly interested in and pushing for a responsible supply chain, right from when the shark is landed through to the consumer, and that the right information is available for consumers to make informed decisions. Those two pillars work hand in hand – sustainable fisheries and responsible
trade. The third pillar is looking at where endangered species are, specifically where their populations have deteriorated to the point where they are classified as threatened. Then we will work with a number of organisations including television partners to push for wildlife protection measures, legislation and then enforcement of that legislation. Why is it so important to save the sharks? What would happen if they were to go extinct? It’s important to remember that not all sharks are the same. They differ hugely, in size and behaviour especially. But on the whole, we think of sharks as being apex predators, and in this position on top of the food chain they are inadvertently responsible for maintaining ocean health. If you were to remove them, you threaten both the health of the
ocean and the ecosystem within it. We believe that if we can maintain healthy shark populations we have a better chance of maintaining a healthy ocean, which has all sorts of benefits for us. Is there anything normal people can do to help stop sharks dying out? Yes, anything they can! Supporting shark conservation is obviously very important, not only by donating money but also by giving us a voice. You can get involved in science projects, by going out and searching for sharks and recording any sharks that you come across, and even by going on our egg shell hunts that we run each year in the UK. You can do this without getting your feet wet! You can also help by signing shark petitions and just generally by having a voice. Push for the policies that will protect sharks in the future.
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Sharks & Ocean Predators
TACKLING SHARK
ATTACKS There’s no mistaking sharks are precision killing machines – it’s in their nature to be voracious hunters and it’s why they have survived for millions of years. But what if when humans stray into their watery realm, and sharks simply do what comes naturally? Here are three particularly gnarly species you want to stay clear of during a dip… 34
Tackling shark attacks
Great white shark The infamous king of sharks
Able to detect a single drop of blood in 100 litres (25 gallons) of water, the great white is an incredible hunter. When it comes to human encounters, this shark holds the record for the highest number of attacks – a total of 314 incidents since records began in 1580, although only 80 of these have resulted in death. Great whites are naturally curious creatures, and the majority of attacks are thought to be test bites, where the shark samples what it thinks to be prey, but then spits it out again. You can read more about great white shark attacks and their hunting techniques on page 48.
GREAT WHITE SHARK Carcharodon carcharias Class Chondrichthyes
Territory Temperate waters worldwide Diet Carnivore Lifespan Up to 70 years Adult weight Up to 3,000kg (6,600lbs) Conservation Status
VULNERABLE
Tiger shark This fish isn’t fussy with its food The tiger sharks isn’t known for having a gentle demeanour, and its hugely varied diet means it will eat almost anything that crosses its path. Living in the tropics, this species has been known to use its razor sharp teeth to tear into sea turtles, stingrays, sea snakes and even old tyres. On rare occasions, humans have been added to that list; a total of 31 fatal and 80 non-fatal attacks have been recorded, putting the tiger shark second only to the great white when it comes to human threat.
TIGER SHARK Galeocerdo cuvier Class Condrichthyes
Territory Tropical and subtropical waters worldwide Diet Mostly fish, but has diverse diet LifespanUp to 50 years Adult weight 385-635kg (850-1,400lbs) Conservation Status
NEAR THREATENED
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Sharks & Ocean Predators
Bull shark A cranky character that hangs out in town Bull sharks are considered to be some of the most dangerous sharks in the world. They are a particularly aggressive species and like to live in shallow water, putting them in close range of populated shoreline areas. Bull sharks can also thrive in freshwater, and have been known to swim up the Mississippi and Amazon Rivers. Since records began in 1580, there have been 100 unprovoked bull shark attacks on humans, 21 of which have been fatal.
BULL SHARK Carcharhinus leucas Class Chondrichthyes
Territory Tropical and subtropical waters Diet Fish, other sharks, marine mammals Lifespan Up to 16 years Adult weight 90-230kg (200500lbs) Conservation Status
NEAR THREATENED
Why do sharks attack? Sharks are misunderstood creatures, and we are visitors to their habitat Of all the species of sharks that live in our oceans, there are only a mere dozen that have been involved in attacks on humans. In 2014, there were 72 unprovoked shark attacks on humans. Considering the number of people who swim, snorkel and dive in oceans worldwide, these attacks are extremely rare. The number one offender for human attacks is the great white. However, these sharks are naturally inquisitive and will investigate anything that they don’t recognise in the water. They use teeth like we use our hands, to feel something new. Sharks will not actively hunt or eat humans because we are too bony for them to digest. They are likely to only take an exploratory nibble of humans, and much prefer to eat seals, which are covered in a layer of soft blubber. When it comes to avoiding shark attacks, there are a few tips to bear in mind. Don’t go in the water if you are bleeding, and make sure to stay in groups, as sharks are more likely to be attracted to lone swimmers. Avoid swimming in the early morning and late afternoon, when the sharks are most likely to be on the hunt for unsuspecting prey.
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Tackling shark attacks 5 things that are more likely to kill you than a shark Being attacked by a shark is a terrifying yet very unlikely prospect. Instead, start worrying about these…
Coconut Around 150 people each year are killed by coconuts falling on their heads – that’s 30 times more than annual shark fatalities.
Mosquito Through the diseases that it spreads, the tiny mosquito is responsible for the deaths of up to 725,000 people every year
Lightning The odds of being struck by lightening are 1 in 300,000, but the odds of being attacked by a shark are only 1 in 1.5 million.
Rip Currents A much greater oceanic threat is rip currents. The average number of deaths from swimmers getting caught in these is 21 per year.
In the unlikely event that a shark attacks you, forget the traditional ‘punch it in the nose’ advice – punches don’t work well underwater! Your best defence is to jab the shark in its delicate eyes and gills using your hands and feet, or better yet some kind of weapon, to drive it away. If the shark retreats, swim calmly to safety, or shout loudly for help. Any thrashing around in the water could attract the shark back.
“Your best defence is to jab the shark in its delicate eyes and gills”
© Getty Images; Corbis; Thinkstock
Snake bite Poisonous snakes bite 5.5 million people each year, resulting in 100,000 human deaths and a further 300,000 amputations.
What to do if a shark attacks
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Sharks & Ocean Predators
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Great white sharks
All About
Great white sharks A misunderstood giant of the deep, or a calculated ice-cold killer? Discover more about the great white’s advanced adaptations and learn about the life of this leviathan of the oceans
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Sharks & Ocean Predators
Inside a great white Get under the skin of these fearsome predators to see how their bodies have evolved cunning adaptations for both speed and stealth, placing them as voracious hunters at the very top of the ocean’s food chain
Eyes The great white’s eyes function rather like a human’s and are highly sensitive to changing light and colour. When the shark attacks, it rolls its eyes back to keep them protected.
Brain
Nostrils
GREAT WHITE SHARK Carcharodon carcharias Class Chondrichthyes
Territory Throughout most temperate seas and oceans Diet Carnivore Lifespan Up to 70 years Adult weight 2,300kg / 5,070lbs Conservation status
VULNERABLE
Body temperature This cold-blooded shark is able to warm its body above the heat of the water temperature, for more-efficient hunting.
Power bite The great white’s bite is strengthened and braced from behind by a cartilaginous structure called the hyoid arch, so that the shark can deliver a bite of 1.8 tons.
Heart
Pointed teeth The great white’s preference for seals means the dentition of the upper jaw is more pointed in shape, enabling it to impale and immobilise its catch.
Strong jaw The upper jaw isn’t fused to the skull, meaning the shark can thrust it forwards to trap prey.
JUVENILE
INFANCY Survival of the fittest 0 months Even before birth, great white pups are already voracious predators and have been know to eat one another while still in the womb.
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Liver With no swim bladder like other fish, the great whites stay buoyant in the water thanks to a large oil-filled liver.
In the shallows 10 minutes Female great whites give birth to between five and ten pups at once, usually in the safer shallow waters of coastal seas.
Small white sharks 0-4 years Great white shark pups are born as miniature replicas of their parents. Giving no parental care aer birth, the mother abandons the pups almost instantly.
MATURITY Mini killers 4-7 years Despite their relatively small size, juvenile great whites are already acute hunters, feeding on fish, invertebrates and other smaller marine creatures.
Male sexual maturity 8-9 years Aer around nine years, when they measure roughly 3.3 to 4 metres (11.5 to 13 feet) long, male white sharks reach sexual maturity.
Collagen The skin has a layer of collagen that anchors the swimming muscles and acts as a kind of external skeleton.
Skin The skin is formed of tiny tooth-like dermal denticles, providing a tough armour.
Gills Five gill slits provide a huge surface area for absorbing oxygen from the water.
Fins The dorsal fin along the back provides stability, the pectoral fins give lift and the caudal fin at the end is used for thrust.
Muscle types Red muscle is used for cruising and runs just underneath the skin, carrying oxygen from the gills. White muscle contains no oxygen and is used for short bursts of energy. Neural tube
Skeleton The skeleton is made of a strong fibrous substance called cartilage. This is much lighter and flexible than bone, enabling the shark to be supple and save vital swimming energy. Intestines
Closest family
Crown tip
Cousins of the great white include…
Retractable teeth The dentition of great whites is retractable and teeth rotate into place when the shark opens its jaw. They are attached to pressuresensitive nerve cells for tactile responses.
Reproduction 9+ years Not much is known about the great white mating season. Females will give birth every two years, having a year off to recuperate.
Cusplet Enamel Crown
Root
Solitary predators 9+ years Aer mating is concluded, the great whites will separate to roam the ocean and hunt alone. They will only congregate again to copulate and produce the next generation.
Female maturity 14-16 years Females take longer to mature than males, but actually grow much larger – up to 4.2 to 4.8 metres (14 to 16 feet).
Mako shark A fellow member of the Lamnidae family, the mako shark shares many features with the great white. At around three metres (ten feet) in length, they feed on cephalopods and bony fish, with similar hunting tactics to their great white relatives.
Dogfish This creature belongs to the same subclass as the great white sharks, Elasmobranchii. They are much smaller than most shark species, but still share some traits, such as a cartilaginous skeleton and rough, almost sandpaper-like skin.
Stingray Another fellow elasmobranch is the stingray. Along with skates, these fish belong to the superorder Batoidea. They share classic elasmobranch traits with great white sharks and dogfish, but are flattened with enlarged fins.
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Sharks & Ocean Predators
Impeccable hunting The anatomy of this killer fish is honed in perfect harmony with its highly effective hunting methods, leaving almost nothing safe in the ocean
Diet and feeding The menu for great whites is varied and wide-ranging… An average male great white shark eats 30kg
/ 66lbs
of food every ten days.
70% of their diet consists of marine mammals, such as seals and sea lions.
Occasionally they will supplement their diet with fish, cetaceans and turtles.
That’s 1.2% of its total body weight.
01 Inverted
02 Scope prey
03 Approach
04 Surface charge
Although rarely used, some great whites have even been observed swimming upside-down towards their prey to cause confusion.
Using its amazing array of senses, a great white shark will stalk its prey and wait for the opportune moment to strike.
The shark swims below its quarry, then shoots upwards with a powerful burst to incapacitate the prey in its jaws.
If the prey escapes this first attack, the shark follows up with a rapid rush towards the creature to confuse and disorientate it.
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Great white sharks
The importance of hierarchy Not just colossal hunting machines, great whites have intricate social lives and family bonds Marine biologists are only scratching the surface when it comes to understanding how great whites tick. As solitary fish, there’s some social hierarchy when individuals meet. In areas with regular populations, large groups gather at certain times of year. These gatherings aren’t fully understood, but coincide with the boom of seal populations. Around this time, young great white sharks will hang back from large kills to let the larger and older sharks take the lion’s share. Physical gestures have shown that body language is also used to communicate. Most social interaction between great whites seems to be in order to establish rank,
which in turn helps to avoid conflict. Despite having a reputation for being stone-cold killers, they aren’t keen to fight one another. In terms of hierarchy, the larger the shark, the higher its rank; similarly, residents come before newcomers and females before males. When many sharks gather, competition for prey can be fierce, so the sharks in some areas appear to reduce conflict by respecting boundaries. When it comes to hunting, ambush is the method of choice. Hunting behaviour relies on a potent mix of precision and efficiency and the sharks use their developed brains and keen senses to hone in on their prey. Using the scent
organs in its snout, a great white can sense tiny amounts of blood in the water up to five kilometres (three miles) away. They have also been witnessed raising their heads several feet out of the water, and some think that this is to get a sniff of scents in the air. The sharks must keep swimming to stay alive, moving a flow of water over their gills to keep oxygen pumping. It’s not known how they sleep, but some have been seen moving slowly, or even being stationary in gullies. By facing their heads into the current, they’re able to catch a breather between mouthfuls as the water passes into their gills.
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Sharks & Ocean Predators
Epic migrations Satellite tagging has shown these fish can travel through miles of open sea
Atlantic journey This shark, nicknamed Lydia, has shown the true ability of great whites to swim vast distances. She headed out into the open Atlantic and swam over halfway to Europe.
The urge to migrate Great whites are thought to migrate to feed, coinciding with the availability and quality of food in particular regions. This could also be to do with mating or pupping, with the sharks heading off to find the most suitable mate, or the ideal place to give birth. Evidence suggests that all sharks appear to migrate, but scientists are still trying to figure out when and why.
Regular routes Great whites tagged between 2000 and 2008 off the coast of California showed regular migrations all the way to Hawaii, back to California and in between.
Physiological demands Although journeys may be erratic, many sharks are known to migrate from their home ranges to other areas rich in food. On the journey it’s the shark’s fatty liver that enables it to swim marathon distances, but it can quickly replenish its reserves once it arrives.
Trans-oceanic voyage A female great white named Nicole broke great white records when she swam 11,100 kilometres (6,900 miles) in 99 days from South Africa to Australia.
Solitary life
Born
The baby great whites are much like their parents in that they swim the oceans alone.
survivors How pups are born with survival instincts
Great white offspring are almost miniature versions of their parents. Unlike other creatures, there are no life cycle stages to undergo for young great whites. This means that simply eating plenty to grow fast and reach the gargantuan size of their fearsome shark elders is all the little sharks need to do. With no parental care whatsoever, shark young come built with all the instinctual survival knowledge they need straight out of the womb. Initially they will feed on small fish and bottomfeeders – these are tasty and nutritious bite-sized morsels for the mini sharks. At around 1.5 metres (five feet) long, the offspring are by no means tiny, but this small size can make them vulnerable to larger predators. Though they’re thrown in at the deep end, learning to survive in this way helps the young sharks grow into hardened adults.
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Prepped and ready Baby sharks develop their killer senses in the womb, so when they are born, they’re ready to hunt.
Sticking to the shallows In their first few weeks, hungry little great whites mainly stick to shallow water where meals are plentiful.
Great white sharks
Mating rituals include biting These slow-growing ocean leviathans keep their mating secrets closely guarded Great white sharks reach maturity at around nine years old for males and 14 years old for females. When the time comes to find a mate, it’s thought great whites may make long journeys to hang out in areas where other sharks are looking for suitable partners. These congregations of great whites looking for love seem to occur in the same places each year. Hormones are believed to play a big part in shark mating rituals, with each male and female producing a certain chemical and releasing it into the water to let members of the opposite gender know that they’re ready to mate. Some great whites have even been observed making constant vertical dives in order to spread this chemical scent throughout the water column. Courting behaviour isn’t well documented in great white sharks. They may use their supreme swimming strength to zoom upwards out of the water and crash back down onto the sea surface with a huge splash, known as a pattern breach, as a mating display. A breeding couple may also swim in circles around each other a little to establish themselves before the male bites the female. This bite may be to signal to her that he is ready, or it may have a more practical use, in
that a bite will keep the pair together. As great white sharks have to keep swimming constantly to maintain the oxygen flow over their gills, a bite may be the helping hand the male needs in order to fertilise the female. Fertilisation is internal for great whites and the male has special appendages known as claspers on his underbelly, modifications of his pelvic fins that he uses to inject his sperm and fertilise the female’s eggs. Once fertilised, the female swims off and the male has no further part to play. Great whites, like many shark species, are ovoviviparous, which means they give birth to live young. The female’s fertilised eggs hatch out within the womb and the young baby great whites will eat any unfertilised eggs, providing them with a source of much-needed nutrients. This can also go a step further and unborn great white young have been known to eat their own brothers and sisters while still in the womb. Although it’s not fully documented, marine biologists generally think that gestation for great whites is around a year. The mother will give birth in shallow water, but then immediately swim away and leave her pups to fend for themselves as soon as they are born.
“After swimming circles around each other, the male bites the female as a signal to her that he is ready ”
Shark signals Body language is used to establish social boundaries
Parallel swim Two great whites swim slowly side by side to size each other up and establish rank, or settle ownership of a kill. Smaller sharks will submit and swim away.
Swim by This behaviour consists of a slow swim past each other, a few feet apart. It may be used to identify each other, or to establish which shark ranks highest.
Hunch display This posture is assumed when faced with a dominant shark and usually comes before either fleeing or attacking.
Splashing A splash fight is quite rare to see between two sharks, but usually determines ownership of a kill. The rules are simple – the biggest splash wins.
Circling Great whites swim around each other in a circle to identify rank.
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Sharks & Ocean Predators
King of the oceans These majestic sharks live in oceans across the world, usually gathering in the shallower waters of the continental slopes. Their principal habitat is the Pelagic zone – the upper part of the water column where light is still in plentiful supply. The sharks will usually stay wherever food can be found, so make their homes near coastal areas populated by plenty of seals and sea lions. Areas where deep water is close to the shore are favourite haunts, as are offshore reefs, banks, shoals and rocky headlands. These sharks also like to cruise around seamounts and island archipelagos, looking for food or mates depending on the location and time of year. Many will make long migrations each year to visit feeding or breeding grounds.
Great whites spend most of their time near the surface, but have been known to dive to around 1,875 metres (6,151 feet) in open oceans. Because of their preference to be close to the shore, they have often clashed with humans, earning themselves a reputation as murderous thugs. This is unfair on the sharks, however, as most attacks are mere cases of mistaken identity. There are hot spots of shark activity across the world, with greater concentrations of great whites off the coasts of South Africa, Australia and California. They’re also found along the coast of Hawaii, most of South America, the Gulf coast, New Zealand and the Mediterranean Sea. Great whites rarely venture into icy waters but some are spotted on the Alaskan and Canadian coasts.
Environmental factors © Alamy, Corbis, Getty, NPL, Thinkstock, Michael HJC, Jim E Margos, G W Sharks
Life in the sea has issues even for these mighty ocean rulers
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Commercial fisheries Great whites can fall victim to bycatch from the fishing industry. The creatures are oen trapped and killed in nets intended to catch other fish for humans to eat.
Poachers Despite their protection, great white sharks are targeted to make shark-fin soup, a supposed oriental delicacy. Poachers cut off the fins and throw the animals back.
Shark nets Designed to cordon off coastal areas and make them safe for humans to swim in, these colossal nets can entangle and kill sharks, as well as other marine life.
Changing climates It’s not easy to predict the affect climate change may have, but alterations in climate may influence prey distribution, which in turn could affect the great whites.
Great white sharks
Why sharks should be left alone Great whites and humans have shared a chequered past. Their fearsome features, gigantic size and fierce array of teeth, alongside fictional films such as Jaws, have painted a rather poor picture of these misunderstood fish. Although shark bites do happen, they are very rare. In 2013 there were 53 unprovoked shark attacks in the USA, two of which were fatal. Compared with the amount of people in America who swam in the sea throughout the year, that number is very small. The truth is that sharks don’t want to eat us. We aren’t fatty enough for their nutritional needs and we have too many bones to digest. Shark attacks on humans don’t usually conform to the usual hunting strategy of the great white – ambushing and rushing the prey from beneath. If they really did believe we were their food, shark attacks would probably be much more common. Despite this, shark culls to protect public safety are in effect in some areas of the world. For example, in Western Australia shark culls began in January 2014 and more are expected to happen after the region was given an exemption from the Environment Protection and Biodiversity Conservation Act to kill great white sharks. As this species are so slow to reproduce and grow, culling could have catastrophic impact on breeding populations of these majestic animals.
Nearest neighbours The great white shares its ocean home with countless other amazing marine species
Coral Forming massive offshore reefs, the great white is a frequent visitor to these ecosystems. Coral is made up of tiny invertebrate animals that live in colonies and secrete a hard, calcium-carbonate skeleton.
Squid A Pelagic dweller alongside the great white, squid species live in the top layers of the ocean right down to the depths. They move by jet-propulsion from their siphon, reaching up to 40 kilometres (25 miles) per hour.
“Their fearsome features have helped paint an undeservingly negative picture of a misunderstood fish”
Seals The favourite meal of the great white, seals, alongside sea lions and walruses, live on shorelines across the world and are full of fatty, blubbery goodness – just how the sharks like it.
In our culture Sharks have captured many imaginations, cropping up in blockbuster films and even sports Jaws Responsible for many people’s shark fears, Steven Spielberg’s 1975 thriller follows the story of a killer shark on the loose around the beach resort of Amity Island.
Bruce in Disney Pixar’s Finding Nemo Finding Nemo went some way to portray great whites in a better light, with Bruce’s mantra being “fish are friends, not food”.
The Devil’s Teeth by Susan Casey This aims to tell the truth about the great whites of California’s Farallon Islands, as well as the scientists studying them.
Symbol of strength The shark tooth has long been used as a symbol of male strength and masculinity shark tooth necklaces came to prominence during the 1970s.
Bony fish The great whites share their watery realm with thousands of species of bony fish – from ocean-going giants, shoals of tiddlers along the shore and brightly coloured exotic species teeming in the reefs.
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Sharks & Ocean Predators
GREAT WHITE SHARK Carcharodon carcharias Class Chondrichthyes
Territory Throughout most temperate seas and oceans Diet Carnivore Lifespan Up to 70 years Adult weight 2,300kg / 5,070lbs Conservation status
VULNERABLE
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Great white sharks Victims of myth and mankind’s myopia, discover the truth behind the hunting habits of these colossal killers
Older seals know what lies in the murky depths of the ocean. They keep watch from the rocks, looking for telltale signs of danger – a flash of fin or a tail – but even the world’s largest predatory fish can go undetected if it lurks just a few metres below the surface. It’s tough to conceal the immense size of a fully grown adult great white shark, but the low-light conditions of the ocean depths and the grey body that blends in with the rocky reef habitat helps its cause. Its infamous name comes from its white underbelly, which will be on full display soon enough. When the great white senses an opening, it forgoes stealth for full-blown ambush mode. Torpedoing vertically through the water at fin-tastic speeds of up to
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Sharks & Ocean Predators kilometres per hour (25 miles per hour), the velocity launches both shark and seal clear of the water in what’s known as a Polaris Attack. With jaws opening wide, the predator tries to catch its prey but this meal brings a whole new meaning to the term fast food. Seals have agility on their side and will attempt a zig-zag manoeuvre in a bid for freedom, but death comes quick this time. Rows and rows of serrated teeth bear down on the blubbery flesh, as it’s shaken violently from side to side and, within minutes, the seal’s inanimate body is sliding down the shark’s throat, whole. In that first bite, the great white shark’s sensitive taste buds can assess the energy content of its prey to see if it’s palatable. Fat and blubber are energy-rich food that sharks need to feast on, which has been proven in an experiment where sharks were tempted with carcasses of seals, pigs and sheep. The great white attacked all three but rejected the sheep, indicating fat is required to meet the high energy demands of a great white. Too low, and it won’t be worth the effort (and energy) of attacking. When chasing prey, their streamlined bodies and powerful tails propel them through the water with ease, while their fins enable them to have effective control over their movement. The crescent-shaped caudal fins at the end of a shark’s body is the main propulsive structure, while the pectoral fins (on its sides) are for turning and braking and the infamous dorsal fin, which can be seen poking out the water, is crucial for keeping it upright. Its warmer body temperature (see page 30) sharpens its sight and boosts brain activity. It gives this daytime hunter an advantage while up against prey that are not only
“Despite what Hollywood would have us believe, we’re far too bony and lacking the essential nutrition a shark needs for a hearty meal” clever, but also equally adept swimmers. In addition to seals, it also eats dolphins and whales, but smaller juveniles will feast on tuna, seabirds and even sea turtles. Notice how humans aren’t on the menu? Despite what Hollywood would have us believe, we’re far too bony and lacking the essential nutrition a shark needs for a hearty meal and, after a sample bite, it usually spits out its victim. But unfortunately for sharks, and the occasional swimmer, a wetsuit-clad human on the surface of the water closely resembles its normal prey. Add a surfboard to the equation and the silhouette is uncannily like a shark’s favourite dish, particularly when they are in the vicinity of their normal prey. However, once the shark has realised its error, it’s usually too late and the victim will have been claimed by blood loss or drowning. This man-eating image has largely been blamed on the 1975 movie Jaws, which portrayed them as indiscriminate killers. While a shark attack is a potential danger in marine waters, it’s worth putting this risk into perspective. As the Florida Museum LEFT Seabirds are occasionally on the menu of younger sharks, though would be too scrawny for larger adults
Why they don’t eat humans Though we fear them, we’re not nutritional enough for a shark Attacks on humans are extremely rare; in fact, you’re more likely to get hurt on your way to the beach than you are to get bitten by a great white shark. What’s more, it’s even rarer for the attack to be fatal. In 2014, of the 72 reported shark attacks worldwide only three were lethal. Our muscle content means we don’t make a substantial meal for a great white, which needs plenty of energy that blubbery mammals like seals offer.
“Thank you for not eating me!” During a surfing event, Mick Fanning had a very close call when a great white shark misstook him for a tasty treat It was a gorgeous day at the J-Bay Open in South Africa, the waves were rolling in perfectly, and professional surfer Mick Fanning was at the top of his game. What could possibly ruin this picture? The daunting image of a shark fin emerging out of the water behind Fanning. In one of the most harrowing 30 seconds in live television, viewers watched as Fanning struggled with the shark and disappeared behind a wave. Lifeguards feared the worst and hurried to his presumed location with jetskis. The audience, including Fanning’s family and friends, were relieved when the next shot showed Fanning safe on a jetski. But what happened underwater? Well, apparently one of the most impressive showdowns between man and shark. Fanning described being dragged down by the great white and – in true “fight or flight“ fashion – punched the shark in the nose. The few punches he managed to throw were effective, as it confused the shark enough for Fanning make his quick getaway and get onboard the jetski. When asked what he’d do if faced with the shark again, he said he’d say: “Thank you for not eating me!”
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Great white sharks
The great white in numbers 20-30 03 25 05-07 mph
The speed a shark can reach prior to an attack to pursue and catch its prey.
The rows of teeth ready to move into a frontal position when one is lost or broken.
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%
Shark surface attacks that actually result in successful kills.
YEARS The average lifespan of a great white in the wild.
tons
How much a great white can weigh up to.
06 300 CM
25-30
metres How long they can grow.
The number of teeth a shark can have in its mouth at any one time.
The amount a great white grows per year.
“A great white can smell a seal colony from 2 miles away”
ABOVE Propelling itself at speeds of up to 25 miles per hour, the shark’s Polaris Attack is sudden and deadly BELOW Breaching is a technique employed frequently by great whites when hunting surface-dwelling prey
of Natural History points out, bees, wasps and snakes are responsible for far more fatalities every year and, in the United States, up to 30-times more deaths occur as a result of lightning strikes per year than from shark attacks. In reality, great whites have more in common with human serial killers than the boat-bashing, mindless opportunists of the Steven Spielberg movies. Far from killing at random, a study has shown sharks will find a good hiding spot and return to it time and again, watching specific victims from afar until an opening presents itself. The crucial difference, however, is the motive – a shark
kills purely to eat and survive. As part of the research conducted by Neil Hammerschlag of the University of Miami, Florida, geographic profiling (a police tool for analysing serial crime) was used to observe shark behaviour at Seal Island in False Bay, South Africa. Named for its dense Cape fur seal population, this is one instance where safety in numbers doesn’t apply. A great white can smell a seal colony from over three killometres (two miles) away thanks to its super-sensitive snout that’s covered in sensory cells. It can even hone in on faint electrical signals from hearts and gills. If you’re a living creature in the ocean, there really is nowhere to hide. These finely tuned senses are driven into a bloodthirsty frenzy when this many flippers are found in one place, making Seal Island a prime spot for studying great white attacks. But rather than waiting where the seals congregate, Hammerschlag’s investigation found that larger, older sharks have well-defined anchor points, 100 metres (328 feet) from the seals’ entry-exit point. It’s not an ideal location for snatching prey, but he suspects it’s a balance between prey-detection, capture rates and competition. They attacked early in the morning when the light was low, when no other sharks are around and they preferred victims that were young and alone. Smaller sharks, on the other hand, didn’t have such distinct lairs and had lower success rates, suggesting either sharks refine their strategy with experience, or the larger specimens are purposefully excluding them from the
“It can even hone in on faint electrical signals from hearts and gills. If you’re a living creature in the ocean, there really is nowhere to hide”
Shark’s eye view There’s no reason for sharks to see us as their natural prey, so why do attacks occur? One theory is mistaken identity. Scientists have noticed that most incidents happened when water conditions were poor, so the shark may have confused a swimmer with their regular food. Another reason could be that these apex predators have nothing to fear, leading them to be incredibly curious. However, there’s no way of knowing for certain what an unknown object is without a sample bite.
Human surfer
Sea turtle
Seal
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Sharks & Ocean Predators hunting hot spots. University of Florida shark researcher George Burgess sums it up best: “Sharks are like many other predators that have developed patterns to their attacking, which are obviously beneficial as a species.” Sharks have been patrolling the oceans for about 450 million years and it’s believed that the great white is an ancient relative of one of the deadliest killers the ocean has ever known – the Megalodon. This giant clocked in at 17 metres (55 feet) and weighed 25 tons, with a mouth that could swallow five adult humans in one gulp. But as these monsters began to die out, the mammals we know today – dolphins, whales, seals – began to flourish and became a veritable blubber buffet for the shark. The great white is a true survivor, evolving to become the most formidable predator of the ocean today. Just like its terrifying ancestors, the grite white’s only real weapon is the toothy grin. Inside those gaping jaws are several rows of triangular, serrated blades that are typically over seven centimetres (three inches) long. The top set are broader, designed for tearing through chunks of flesh and bone, while the thinner lower teeth grip onto the prey to hold it in place. This enables the great white to feast on carcasses that would be too big to swallow whole. Feasting solely on meat, the great white doesn’t need grinders for chewing on plants, so every chopper is sharp and pointed. Whenever a tooth is lost or broken there are several rows of teeth behind it, ready to move into position,
as they are attached by cartilage rather than bone. This happens so frequently that a shark can have over 300 teeth in its mouth at any one time - crucial for a successful killer. It’s not only the teeth that make a shark’s bite truly fearsome though, as they have a unique structure where the upper jaw is not attached to the skull, like a human mouth. Like other sharks, the great white’s jaw is held in place by connective tissue so the entire mouth can thrust outward from the head in order to latch onto its prey, and this bite force has been estimated at an unbelievable 4,000 pounds per square inch. Generally, the species is a grey, brown or blue colour that blends in with the water and rocks, making it tricky to spot from above. When viewed from the side, the great white’s universally white underbelly (known as countershading) makes the outline difficult to define. The unique skin texture is also part of shark’s secret to sneaking up on prey undetected. Unlike regular fish scales, their skin is covered in flat, v-shaped scales called dermal denticles (tiny skin teeth) that would feel smooth if you were to stroke a shark from head to tail, but rough if rubbed the other way. These denticles are lightweight, reducing drag and enabling the shark to swim faster and preserve energy, as well as decreasing water turbulence from swimming. This makes the shark a silent assassin, giving enormous advantages. Designed for stealth and built for the kill, the shark is also extremely intelligent and
will tailor its tactics depending on the prey. While the ambush works for Cape fur seals in South Africa, when faced with the much larger elephant seal off California, the great white aims to bite the hindquarters to stop the seal in its tracks and then waits while its victim bleeds to death. Smaller harbour seals, however, are grabbed from the surface and dragged underwater until they give up the struggle. California sea lions are talented swimmers and are typically attacked from below, hit mid-body and then hauled to the depths. Dolphins present a trickier kill, though, as they are wisely cautious of the great white and have echolocation to boot, so the shark attempts to go undetected by striking from above, behind or below. Cunning and clever, the great white shark is the apex predator of the ocean, and yet the IUCN lists the great white as Vulnerable. Trophy fishing and the commercial fishing industry are to blame for the decline in numbers, but without this remarkable species, the oceans would suffer. This is because great whites don’t just devour healthy prey, they also scavenge on weak, injured and even dead creatures too, performing a crucial role in keeping the ocean clean. The great white ensures that other species are kept fitter and stronger by eliminating the weak and feeding on animals such as seals and whales that have few predators. It’s survival of the fittest and the great white shark is a shining example that we should strive to protect.
“The great white is an ancient relative of one of the deadliest killers the ocean has ever known”
Eyes shut Seals can cause damage to sharks’ eyes, so they will roll them back into their head when attacking, to prevent them from losing their sight.
Open wide A shark’s jaws are not connected to the skull, enabling them to thrust forward when the prey is within reach.
Surprise attack The great whites boost their chances of success by launching a vertical charge from the depths to surprise their target.
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Great white sharks
How a seal escapes Giving chase These smaller marine creatures are highly agile and will attempt to throw the shark off their tail by performing a zig-zagging motion through the ocean. The shark will attempt to pursue the prey across the surface but the longer the chase, the more chance the victim has of escaping. The impact The great white will aim to kill or at least injure the prey on impact by using the breach method. If the shark fails to capture the target in its jaws, however, then marine mammals such as seals, dolphins and whales stand a good chance of giving the shark the slip.
Quick questions with an expert Name: Richard Ellis Role: Marine biologist Organisation: Various
You were friends with the late Peter Benchley, author of Jaws. How did he feel about the public’s reaction? He would send me the dra copies of his future manuscript and I would say to him: “This is nonsense, sharks don’t eat people,” and he would say “It doesn’t matter, I’m writing fiction.” It was hardly his intention to initiate a vendetta against sharks, but he ended up doing just that. Everyone saw the movie and thought the only good shark was a dead shark. Later in his life he became a dedicated conservationist of sharks, but the damage was already done. Aer Jaws, there were attempts to keep great whites in captivity. Can you tell us about Sandy? Sandy was the first great white to be put on exhibition and
she drew tens of thousands of people to see the ‘man-eater’. Aquariums wouldn’t fish for them, but if a shark was trapped accidentally then it could be rehabilitated before being set free. Sandy refused to eat, though, and she kept bumping into a particular area of the tank because it turned out there was an electrical leak. They only kept her for a few days before putting her back in the ocean.
What fascinates you most about the great white? How beautiful they are. As a child, I liked drawing planes because they’re powerful, fast and well-designed and this is an animal that fulfils many of these specifications. Then I researched them and realised how little we knew, so the first book I wrote was called The Book of Sharks, which attempted to identify the truth about these creatures.
© Alamy; FLPA; Thinkstock; apexpredators.com
Could you tell us about your first up-close encounter with a great white shark? It was 1985 when I went in a cage with great white sharks in south Australia as part of an assignment for National Geographic. At this time the movie Jaws had come out and in the film the shark breaks through the bars, so the first time you experience the shark in a cage like that, you’re terrified. Aer a while you realise the shark is just curious, it might even bite on the cage bars, not because it’s trying to bite through them, but rather because the metal gives off an electrical current, which sharks are attracted to. The whole operation was arranged by Rodney Fox who was one of the first major victims of the great white, having nearly been bitten in half in 1963. It took over 400 stitches to put him back together, but he was back in the water within six weeks.
“Everyone saw the movie and thought the only good shark was a dead shark” 53
Sharks & Ocean Predators
Secret powers of an intellectual ocean beast that uses every part of its body as a powerful weapon – not least its bizarre elongated face 54
Hammerhead sharks
Meet the expert
Sensitive touch
DEAN FESSLER
Blood detection
Education officer Shark Research Institute www.sharks.org Divemaster and shark researcher Dean Fessler has been working at the Shark Research Institute (SRI) for over 20 years and has performed research across the globe. The institute has field offices in 11 different countries and they work to track sharks, study their DNA and behaviour and educate the public about shark conservation.
Electroreception 360° vision Discerning taste Sensing pressure 55
Sharks & Ocean Predators
Sensitive touch Shark skin can detect much more than a simple touch, it can recognise a temperature change of as little as 0.1 degrees Celsius. Sharks use this sense to navigate to fronts of cold water which are nutrient-rich upwellings that attract prey. They can then track prey by following cold currents. Despite being so sensitive, shark skin is still very tough. Rather than
being covered in rounded scales like other fish, sharks have pointed scales called denticles that are only 0.01 millimetres wide. These are toothshaped and offer the shark important protection from their predators, as well as streamlining its body. This combination of armour and sensitivity helps the shark maintain its brilliant predatory advantage.
Blood detection The hammerhead shark’s sense of smell is one of the most important in their arsenal, and a shark is able to detect just a teaspoon of blood in an Olympic-sized swimming pool. Hammerhead sharks achieve this amazing sensitivity by having two nasal cavities called nares, which each have an entry and exit openings. Inside the nares are a maze of chambers lined with skin folds covered with the all-important scent detectors. The cells that decipher smells send this information to the brain, where the shark decides what course of action they should take. Two thirds of a hammerhead’s brain weight is dedicated to decoding smells, making them some of the most advanced sniffers in the sea.
Nasal cavity Sharks have one of the best senses of smell of any ocean animal
Scent- detecting cells Blood
Skin folds
Nerves
Tail The powerful tail is heterocercal (asymmetric), giving the hammerhead shark an edge as it turns quickly and beats the powerful tail to swim at a top speed of 40 kilometres per hour (25 miles per hour).
Streamlined The torpedo shape of the shark’s body is the ultimate in streamlining technology and helps propel the hammerhead through the water. It is this hydrodynamic shape that inspired the shape of aeroplanes.
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“Sense of smell is one of the most important, and a shark is able to detect just a teaspoon of blood in an Olympic-sized swimming pool”
Hammerhead sharks
Electroreception The face is covered with tiny black spots called the ampullae of Lorenzini, which “detect electric fields in the water” according to Fessler. They’re open pores filled with electrically conductive material. “The ampullae contain a jelly-like substance which vibrates when an electrical signal is detected.” The base of the pore is covered with tiny hair-like cilia, which respond to changes in electrical currents. Just like the hairs in a human ear detect the direction and volume of sound, the shark’s cilia can distinguish tiny changes in electric currents. “The ampullae can pick up electrical signals from muscle contractions of prey,” he continues. A great hammerhead shark has over 3000 receptive pores, making them masters of electroreception.
In low light a hammerhead shark can see 10 times better than a human could
Teeth The sharp serrated teeth of a hammerhead are constantly growing to replace any that become embedded in prey, and new teeth move forward like a deadly conveyer belt.
360° vision Hammerhead sharks have brilliant 360-degree vision. “Shark vision is very good,” explains Fessler. “They are able to scan over 180 degrees with a single eye, which means the visual fields of both eyes overlap”. This wide spacing of the eyes comes at a cost, however.
“Hammerhead sharks eyes are spaced so far apart, they have larger blind spots in front of them than other sharks” continues Fessler. Behind the retina are mirrored crystals called the tapetum lucidum, and when light hits this layer of crystals it is reflected several times.
Inside a shark’s eye Sharks have an extra layer at the back of their eyes that helps with night vision Fins The dorsal and pectoral fins of the shark slice through the water acting as natural rudders and stop the hammerhead from rolling sideways or pitching forwards when in pursuit of prey.
Tapetum A layer of crystals reflects light towards the rods and cones to assisit with low light conditions
Cornea Light enters though the cornea
Light
Face The hammerhead’s wide T-shaped face helps it turn quickly in the water, and the large surface area is packed with electroreceptors, making it the most successful detector of electric currents.
Rods and cones Light sensitive cells send signals to the brain
Retina skin
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Sharks & Ocean Predators
Using taste A hammerhead’s sense of taste isn’t as well-developed because their other senses do most of the work. Once the shark has seen or smelled the prey the shark has to give it a good chew to discover exactly what it tastes like. Sharks do have taste buds, but they can only detect flavour once the item is inside the mouth and items that are foul-tasting will be spat out. This has been demonstrated by sea otter carcasses that are found floating out at sea that exhibit bite marks. Sharks don’t eat the otters, they simply have a taste and discard them. This also explains why many victims of shark attacks survive, as sharks bite before realising that a human is not suitable meal.
“Sharks do have taste buds, but they can only detect flavour once the item is inside the mouth, and items that are foul-tasting will be spat out” Cupula
Sensing water pressure
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line is made up of pores formed by modified scales and hair cells” explains Fessler. “These open into a canal just below the skin surface. Between the pores is a gelatinous mass called the cupula. As water flows past this, it causes it to bend modified hair cells located within a sensory patch under the cupula, firing off a series of nervous impulses.” Information sent to the brain tells the shark what is happening, even in darkness.
How shark’s skin sensory organs work
Water flowing
Lines of cells along the shark’s sides turn motion in the water into information about where their prey is.
Sense hair
Nerve
Brain
© Alamy, Nature Picture Library, Thinkstock
“Sharks have lateral lines,” Fessler tells us. “This lateral line works by detecting changes in water pressure and direction similar to the way human skin can feel or detect wind or changes in air direction. “All fish species have long grooves down their sides, made of receptive cells called neuromasts. These cells sense minute changes in water pressure and help build a mental picture of their environment. “The lateral
Hammerhead sharks
Hammerheads size up prey before taking a bite
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Sharks & Ocean Predators
King of the sharks
Whale shark
The largest living fish is the whale shark, which reaches an average length of just under 10 metres (33 feet). The largest confirmed individual measured a huge 12.65 metres (41.5 feet) and weighed 21,320 kilograms (47,000 pounds), with unconfirmed reports of even larger fish. The whale shark has thousands of teeth, each of which is two millimetres (0.08 inches) in length, arranged in around 300 rows pointing backward into its mouth. But they are not used for hunting. The whale shark is actually a filter feeder. As it swims along, it opens its wide, square mouth, taking in water and filtering it through a series of cartilaginous spines that cover its gills. They act as a sieve, extracting zooplankton like krill, jellyfish and crustaceans. It might seem unusual that the largest fish in the sea would eat some of the smallest life forms, but the second largest fish, the basking shark, is also a filter feeder, as are many large whales. Schools of fish are often hard to find but eating the abundant microscopic ocean life enables whale sharks to survive on little food. Like many other large species, the whale shark takes a long time to mature, so it consequently has a long life span. They do not reach adulthood until the age of 30, and it is thought that they might live to be 100 years old, although this has not yet been proven. WHALE SHARK Rhincodon typus Class Chondrichthyes
Territory Tropical oceans of the Southern Hemisphere Diet Plankton Lifespan 70-100 years Adult weight 20.6 tons Conservation Status
Friendly fish This shark is a docile animal, and can safely be approached and touched by divers, as is shown here.
VULNERABLE
“As it swims, it opens its wide mouth, taking in water and filtering it through cartilaginous spines that cover its gills ” 60
Whale sharks
Late bloomers Whale sharks take a long time to grow to their full size, finally reaching up to 10m (33) at the age of 30.
Weight
How big? 1 whale shark = 6 family cars
How does it compare to other types of shark?
Whale shark – 12m (46ft)
Basking shark – 10m (33ft)
Great white shark – 7m (23ft)
Toothpick teeth A whale shark has an average of 3,000 vestigial teeth, which have no use in its filter feeding habits.
©Alamy
Megamouth shark – 4.6m (15ft)
Nurse shark – 4m (13ft)
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Sharks & Ocean Predators
Spotters’ guide
WHALE SHARK Rhincodon typus
Whale shark Despite being the largest fish in the sea, the whale shark can be difficult to spot, but this expert guide will help those seeking a sighting Between May and September, whale sharks flock to the coasts of Mexico to feed and spend up to eight hours a day feeding at the water’s surface. They can be seen along the eastern Gulf Coast as well as the west Pacific Coast, but the best place is Isla Mujeres off the coast of Cancun. Whale sharks don’t splash or blow like whales and dolphins, so they can be incredibly tricky to spot. The tell-tale sign of a whale shark are its fins. The dorsal fin and tail can break the water’s surface when the shark is feeding, so spotters should look out for two parallel fins gliding through the water. If you want to guarantee a whale shark sighting, the best thing to do is book a boat tour rather than heading out alone. The guides have years of experience and know the best areas to check. Whale sharks are known to feed
in deep water so it’s safest to have experienced guides to help you locate and even swim with these enormous sharks. They swim at speeds of only one metre per second (two miles per hour), so keeping up with them isn’t a problem. It’s important that spotters don’t use flash photography or touch the animals – whale sharks are listed as vulnerable on the IUCN red list so they should not be disturbed or fed. It’s essential to take waterproof sun cream, plenty of water to drink and a waterproof camera if you have one. Some tour operators even take photos and films for visitors, so you can just enjoy your experience. Most tour companies will provide masks, snorkels and fins, but you can use your own kit if you have it. It is worth investing in a long-sleeved rash guard to keep the sun off your skin.
See them yourself A pick of the tours to see this underwater beauty Cancun Whale Shark Tours
www.cancunwhalesharktours.com CWST are dedicated to preserving whale sharks and a percentage of tour money funds conservation efforts. EcoColours Tours
www.ecotravelmexico.com With door-to-door chauffeuring, customer service is a high priority and whale shark sightings are a daily occurrence.
Where you can see whale sharks Whale sharks live in tropical waters across the globe, but every year they are drawn to the coasts of Mexico like magnets.
Holbox Whale Shark Tours
www.holboxwhalesharktours.com Departing from tranquil Holbox Island rather than the hustle of Cancun, customers get a laid-back experience. Ocean Tours Mexico
www.oceantoursmexico.com Customers get their money back if whale sharks aren’t spotted, and visitors can see dolphins and turtles along the way. Ceviche Tours
www.cevichetours.com Visitors can take a private tour with all refreshments included to make the trip truly magical.
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Cancun MEXICO
Class Chondrichthyes
Territory Tropical oceans of the Southern Hemisphere Diet Plankton Lifespan 70-100 years Adult weight 20.6 tons Conservation Status
VULNERABLE
Whale sharks Quick questions with a whale shark tour guide Roddrigo Sidney operates Cancun Whale Shark Tours (www.cancunwhalesharktours.com) and helps promote conservation When is the best time of year to spot whale sharks? The whale sharks congregate in the waters near Cancun every year from late May through to September. The best action is usually found approximately 20 miles offshore from Cancun. It’s here where the whale sharks will come to feed on krill and plankton. What are the chances of seeing a whale shark off the coast of Mexico? We guarantee sightings from June to the end of August, and prime time is July and August when there are normally 200 whale sharks present. Can you find whale sharks on your own or should you seek help from a specialist? Looking for whale sharks is strictly regulated by the Mexican government and only approved licensed tour operators are allowed to take visitors out to see whale sharks. What should whale shark spotters wear, and what equipment should they take on a trip?
We provide all the required gear, but some participants bring their own personal snorkel gear. We provide each guest with a mask, fins, snorkel and life jacket or optional wet suit. We also have an in water guide with each pair of swimmers. Can spotters expect a close encounter with a whale shark? Yes, really close. It’s like swimming alongside a bus. People describe it as the most exciting thing they’ve ever done. We do, however, have strict rules of engagement with no touching of the whale sharks and snorkellers have to keep a minimum one metre (three foot) distance. What impact does whale shark tourism have on their behaviour and wellbeing? There is ongoing research into the impact of tourism on whale sharks, and the results so far suggest that if the current tour operators follow the rules there is minimal impact. Obviously having no interaction is the best scenario. However, the industry has grown into a lucrative tourist industry so visitors should only go with a reputable company.
“People describe [swimming with whale sharks] as the most exciting thing they’ve ever done” 63
©Alamy; Dreamstime
Whale sharks travel in style with groups of remoras that cling on for a li
Sharks & Ocean Predators
Prehistoric sharks Get ready for the bone-chilling ancestors of modern sharks The waters of prehistoric Earth were as wild and exotic as the land, so few creatures survive that can claim a lineage that goes back as far as sharks. Their design has been so successful that the ancestors of the first sharks still thrive today, 350 million years later, having endured several extinction events and outlived the dinosaurs. Here are five of their most interesting evolutionary checkpoints along the way.
Megalodon
The mega-mouth of the ancient world The fossilised teeth from this fearsome giant of prehistoric waters are so big that up until the seventeenth century, they were thought to be dragon tongues, turned to stone! Megalodon had a similar biting style to modern day great whites, but it was much, much bigger. The reason for its enormous size? Unlike modern sharks, Megalodon hunted the biggest prey in the ocean – cetaceans like whales that were much more numerous millions of years ago. Compression damage in the vertebrae of Megalodon suggests that it could have attacked from below, slamming into the whale’s body and stunning it, before dealing the killing bite.
Stethacanus
The anvil-finned tiddler Some of the ancient ancestors of modern sharks are real curiosities, like Stethacanus: at around half a metre (1.6 feet) long, you’d hardly swim for your life if you encountered it today, but you might pause to consider its odd-looking dorsal fin. Protruding from its back in the shape of a large anvil, it was covered in small spikes, and was thought to reduce drag in the water and allow Stethacanus to swim more efficiently. A pair of tendrils trailed from the rear of its pectoral fins and males of the species had larger spikes, but no one knows exactly what their purpose was. Stethacanus had similar feeding habits to modern sharks, eating the fish and cephalopods (such as squid) of the era.
530mya ~ First Fish appear
250mya ~ Mother of mass extinctions
During an era known as the Cambrian explosion, when most animals first appeared, jawless fish evolved to dominate the seas.
An extinction event even bigger than the one that killed the dinosaurs happened around this time, which killed 99 per cent of marine life. Sharks survived it.
350mya ~ First sharks evolve Nearly 200 million years of evolution later, a weak-jawed and small but successful design for sharks is established in the form of Cladoselache.
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231-66mya ~ Dinosaurs lived and died The dinosaurs arose, ruled and died during this period but once again, sharks survived the extinction event.
Prehistoric sharks RIGHT These fossilised remains of Helicoprion’s teeth look remarkably like an ammonite.
Helicoprion
Saw-toothed mystery shark
Helicoprion is a real oddity of the ancient ocean and has baffled palaeontologists for over a century. The point of confusion is its mouth, which doesn’t conform to any modern standard at all. The structure considered to be its bottom jaw consists of a single blade of teeth that curve around like a circular saw – what is now known as it’s ‘tooth-whorl’. Fossils of its jaw were understandably thought to be an exotic kind of ammonite at first, before being recognised as an appendage of the ancient shark. The lack of wear the fossil suggests that the saw-jaw could have been used to cut through prey like fish and octopus.
Edestus
“Fossils of its jaw were understandingly thought to be an exotic ammonite”
Serrated, scissor-mouthed terror It’s no real surprise that Edestus belongs to the same family as the bizarre Helicoprion: it was a similar shape, grew to a similar size of around six metres (19 feet) long and possessed an equally strange set of gnashers. The teeth in both its top and bottom jaw curved outwards along a single ridge, giving its mouth a scissor-like appearance. How it hunted is still a mystery as the shape of its jaws would have made it harder to swim, although one theory is that Edestus would use its powerful frame to charge its prey and slam its serrated teeth into its side like a spiked mace, which probably would have been a killing blow.
Cladoselache
Ancient ancestor of all sharks
100mya ~ Rise of the modern shark Many easily recognisable features of modern sharks, like the mako and porbeagle, can be found on their ancient ancestors from this period.
2mya ~ Megalodon disappears The last fossil teeth of Megalodon can be traced to around this time, having terrorised the oceans for over 13 million years.
About 350 million years ago, the first of what scientists recognise to be ‘true’ sharks emerged. Cladoselache was the ancestor of them all – to the untrained eye, it more closely resembled the fish from which it had evolved. However, on closer inspection, it had a few key features in common with modern sharks. It was extremely streamlined, with a fusiform body that tapered at both ends, and pectoral fins that acted like stabilising hydrofoils as it moved swiftly through the water. Unlike modern sharks, the shape of its teeth suggests that Cladoselache merely gripped its prey in its mouth before swallowing whole. At just over 1.5 metres (5 feet) long, it was far from the top of the food chain, although it was more than capable of outpacing its predators.
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BIOBOX
Birthday: April 21, 1973 Birth place: Surrey, England Education: Studied English and Theatre Studies at Exeter University Hidden skill: Has a black belt in martial arts Best known for: Handling dangerous animals in BBC TV’s Deadly 60 Other work: Lost Land of the Tigers, The Venom Hunters, The Really Wild Show Awards: Received a BAFTA for Best Children’s Presenter in 2012
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Steve Backshall
A VOICE FOR WILDLIFE
BITING BACK TV presenter and wildlife enthusiast, Steve Backshall, speaks out for sharks in a bid to help save this misunderstood predator From within the gloomy deep-blue, an alien form glinted and glimmered. I hung motionless above the seabed, barely even daring to breathe in case my expelled bubbles spooked the ethereal shape just beyond my gaze. Then, languidly, lazily, the metallic torpedo shape turned towards me, and started to come into focus. The shark was perhaps four metres long, half of which was made up by a scimitar-shaped tail that trailed behind it like a silver banner in the breeze. Its large eyes were billiard ball black, the whole form of the fish seemed cloaked in aluminium foil. As its mirror flanks sinuously twisted side to side, it caught the early morning light, and suddenly the thresher shark was revealed in all its bizarre, brilliant glory. It was one of the most overwhelming wildlife encounters I’ve ever had, with a shark we have right here in British waters. Last spring the UK’s tabloids frothed at the mind with every editor’s fantasy story; a man-eating great white
shark set to terrorise British beaches. It got even more frenzied with the outlandish speculation that ‘Lydia’ (the satellite-tagged shark heading across the Atlantic in our direction) could be pregnant. She could bring a whole new clan of man-eaters to our shores! The story fizzled out as Lydia nosed south towards more familiar waters, perhaps off towards the Mediterranean, but the hysteria had already exposed the British public’s lack of awareness of the wildlife that inhabits our surrounding seas. Though great whites may be rare visitors to our waters, they have never stayed long enough to be caught or identified here. However, many people will be surprised to know that we do have at least 50 species of sharks in British seas. Unfortunately, ignorance of our marine environments and an ‘out of sight out of mind’ mentality has allowed sharks to be pillaged on a scale that is beyond comprehension.
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BELOW The angel shark was heavily hunted in the 1980s, leaving its numbers dangerously reduced, even to this day
In British seas, the nearest thing we have to a great white is the porbeagle shark. This species looks like a smaller version of the great white, feeding on squid, and other fish and sharks, and shares some of the vulnerabilities of its more iconic cousin. Porbeagles are long-lived, but take a long time to mature. They may be pregnant for a year or more, and produce few young. This is a common strategy amongst sharks and other apex marine predators, and has worked fabulously for them over the last 400 million years. However, porbeagles now find themselves facing a ruthlessly efficient hunter: us. The sharks have been overfished to the brink of extinction, mostly for their meat and fish oil, and for their fins, which are used in Chinese shark fin soup. Fishermen searching for more commercially viable species kill many porbeagles as accidental by-catch; indeed they are often sold as ‘swordfish’, which their meat resembles. Now critically endangered in the North Atlantic, fisheries face decades of panic management to make sure paltry populations of this wonderful shark stand any chance of surviving. Porbeagle sharks are not alone in their plight; angel sharks and common skate are functionally extinct in our waters, and overfishing of tope and spiny dogfish (once our most abundant sharks) has almost entirely depleted their numbers. It’s a conservation nightmare that has been repeated a thousand times through recent human history: not recognising that animals are close to extinction until it’s far too late to save them. The reasons I’ve chosen to focus on sharks are manifold. Firstly,
because they have precious few friends, and are fundamentally misunderstood animals in need of an image makeover. Secondly, because they are probably the group of animals that has brought me the most joy and fascination throughout my life, through jaw-dropping and unforgettable encounters. And thirdly because their biology, and our fishing practices, make them peculiarly vulnerable. These are species that are vital to the wider ecosystem health: it is essential that we do not lose sharks from our seas. So what is the answer? We have all the science and research at our fingertips to know what we can and can’t catch, but regulations need to be put in place to make sure we keep our fishing at a sustainable level. History shows us all too often that unrestricted exploitation and unregulated trade leads to population numbers crashing, potentially never to recover. This is all too true for sharks; while some protection and management has been secured for those most under threat, many species remain exposed to the impacts of uncontrolled fishing. We need to start acting now. Organisations like the UKbased Shark Trust are calling on high seas management authorities and governments, demanding the adoption of effective management for stocks before there’s a need to talk recovery plans. Campaigns such as Bite Back are aiming to bring an end to the selling of shark fin soup at UK restaurants. Direct pressure onto supermarkets can change what they choose to stock. Science-based catch limits would be sustainability in action, both for the species and for the communities that rely on them. If we lose the sharks, the mighty, mysterious lords of the deep, our planet’s oceans will be infinitely poorer places.
“They are fundamentally misunderstood animals in need of an image makeover” Porbeagles prefer cold water, generally around one to 18 degrees Celsius (33.8 to 64.4 degrees Fahrenheit)
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Steve Backshall
Sharks under attack
50
73 100 12-15 $700
% million Percentage of UK
shark species listed as threatened
Killed for shark fin soup each year
MILLION YEARS PER KG Number of sharks killed each year
Time for sharks to reach their reproductive age
Average cost of a shark fin
1-2
Number of pups a shark usually gives birth to
$470
MILLION
Gross income worldwide of the film Jaws, which is believed to have contributed to the bad reputation of sharks
30-50 million
Number of sharks killed by being caught up in nets and lines
Why we should be saving sharks instead of fearing them
They are endangered because of us
Their ecosystem needs them
They keep our oceans healthy
It is actually sharks that should fear humans and not the other way around. While only six people were killed by shark attacks in 2014, millions of sharks are killed every year by human activity. The large, shallow water species, such as angel sharks, are under the greatest threat.
Sharks play a hugely important role in their ecosystem. They maintain a balance by keeping populations of other species level and because they prey on the weakest animals, they control the spread of disease and improve the gene pool for future generations.
The ocean is the world’s most important ecosystem. It provides a third of the world with food, produces more oxygen than all the world’s rainforests put together and controls the planet’s climate. Sharks dying out would have a devastating effect on the ocean ecosystem.
What is being done to protect these amazing fish
ABOVE The common skate has been legally protected from fishing in the UK since 2009
© Alamy; FLPA; Nature PL; Thinkstock
There are a number of organisations working to protect the future of sharks. The Shark Trust has been dedicated to shark conservation since it was founded in 1997. Their No Limits Campaign aims to stop uncontrolled shark fishing by working to secure science-based catch limits for shark species. So far limits have been imposed for species such as the spiny dogfish, and most skates and rays. However, there is still work to be done for species like the blue shark, shortfin mako, tope, smooth-hound and catshark. The Trust has also been heavily involved in campaigning to stop shark finning. Although a ban on shark finning was adopted in European waters, it is still legal to buy and sell shark fins in most countries, and the Trust is working with governments to tighten regulations and ensure compliance. Their Bite Back campaign aims to stop restaurants in the UK selling shark fin soup.
WWW.SHARKTRUST.ORG Find out more about the Shark Trust or add your voice to the campaign.
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Ocean Predators The ocean is infested with more than sharks – meet the predators that strike fear in the hearts of oceanic animals
72 The mind of a killer whale
104 Squid vs whale
80 18 facts about killer whales
106 The mimic octopus
82 The beauty of the orca
108 Meet the family of rays
84 18 amazing facts about seals
110 Dolphins
86 Grey seal
118 Spotters’ guide to dolphins
88 Galápagos sea lion
120 Atlantic blue marlin
90 Meet the family of whales
122 Saltwater crocodiles
92 Songs of the humpback
134 Mysteries of the narwhal
98 Journey of the humpback
140 Polar bears
100 Blue whale
150 50 facts about penguins
102 The beauty of the gray whale
110 140
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© ThinkStock; Alamy
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Sharks & Ocean Predators
INSIDE THE MIND OF A
KILLER WHALE Underwater mavericks, the epic brain power of killer whales is key to how they hunt and work together to dominate the oceans
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Killer whales Jaws was wrong: the great white shark isn’t the deadliest marine monster – it’s the killer whale. No animal dares to prey on these 9.8-metre (32-foot) beauties, qualifying them as the apex predators of the ocean, just as humans are the apex predator of the land. It’s human intelligence that keeps us at the top of the food chain, and killer whales – or orcas, as they’re also known – have incredible brain power to match their superior brawn. In fact, they have the second largest brain of any marine mammal (after the sperm whale), but size isn’t all that matters. Intelligence is measured by a number of different factors, with scientists analysing social behaviour, selfawareness and communication when forging lists of the cleverest creatures on Earth. Killer whales tick all these boxes, boasting one of the most complex social structures in the entire animal
kingdom. They travel together in matrilineal groups consisting of a mother and her offspring and since females can live up to the grand old age of 90, there can be multiple generations in one group. While female offspring may go their separate ways and start their own matrilineal lines when they hit sexual maturity (between 10 and 15 years), the male killer whales commonly remain with their mothers their entire lives. That’s not to say they don’t enjoy a healthy social life, though. Closely related matrilines (up to four matriarchs and their offspring) form what are known as pods, which sometimes meet up with other pods of orcas. The final level of the social structure is called a community. This is created when a group of clans in an area meet up and likely find themselves a mate, but the males will always return to their mother’s side.
BELOW Orca whales surface in Lynn Canal with the Alaskan Chilkat mountains seen in the distance
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Sharks & Ocean Predators Amazingly, each pod of killer whales possible to tell which ecotype they belong KILLER WHALE has its own dialect – a series of distinct to. There are actually three forms of killer Orcinus orca call patterns – which gives the group its whales: resident (the most recognised), Class Mammalia own unique identity. As soon as a baby transient and offshore. Not only do they killer whale (called a calf) is welcomed into each sound different, but they also look the world, the family will use these calls and act in a variety of ways. They don’t more frequently than ever. This is so that associate with one another and one day we the newborn can master the lingo, just might even be able to distinguish them as Territory All oceans like human parents use repetition to teach separate species. However, the one thing Diet Carnivore Lifespan 50-80 years their children how to talk. Mothers share they will always have in common is their Adult weight Up to 5,443kg valuable life lessons with their calves and unmatched hunting methods that they / 6tn discipline them from as young as two days pass to their young. Sometimes the adults Conservation status old with a tooth scratch, or by using their will injure their prey and then release it near bodies to restrict the baby’s movement. the juvenile whales to give them a sporting Communicating via distinct clicks and chance of catching their dinner. DATA DEFICIENT whistles also helps to hammer the message Despite actually belonging to the home even further. dolphin family, killer whales can grow An orca’s voice helps it find supper in the first place. to a staggering size of 9.7 metres (32 feet) and weigh To enable the creatures to navigate the murky depths over 5,500 kilograms (12,100 pounds). Dare to peek of the ocean, killer whales emit a clicking sound that inside their jaws and you’ll find over 40 spiky teeth up travels under the water, bounces off an object and then to 13 centimetres (five inches) in length, each of which returns with revealing information about the object’s size, is designed to bear down on blubbery flesh, ripping it shape and distance. This incredible technique is known as apart without the need to chew. They are positioned so echolocation and helps orcas track down their favourite that the upper teeth fall into the gaps between the lower kind of fish – chinook salmon. Once they are locked onto set, which help to lock the prey in place. It’s definitely their target, the incredible orcas appear to go into stealth an advantage when the favourite meals of transient and mode so as to not give the game away too soon. offshore types tend to wriggle, including seals, penguins, Not all orcas have the same diet, however, and just as sharks and other whales. They’ve even been known to their unique dialects differentiate between pods, it’s also take on great white sharks and blue whales, the latter
“Once they are locked onto their target, the incredible orcas appear to go into stealth mode so as to not give the game away too soon”
Killer features
The impressive physical attributes that make the orca such a natural hunter
More than one orca Take a closer look at the different populations of killer whale in the world Offshore Distinguishing features: Smaller in size and females have rounded dorsal fin tips Diet: Sharks, fish Commonly found: North-east Pacific and Vancouver Island. Their name gives away their love of travelling far from shore. Transient Distinguishing features: Females have a triangular dorsal fin Diet: Marine mammals Commonly found: Coastal waters of the north-east Pacific, usually in smaller groups of six. Resident Distinguishing features: Females usually have a rounded dorsal fin Diet: Fish, sometimes squid Commonly found: Coastal waters of the north-east Pacific. They live on a diet of fish and move in matrilineal groups.
Canada Vancouver Island
Pacific
USA
Dorsal fin An orca steers using the dorsal fin, which can reach up to a staggering 1.8 metres (six feet) for males.
Blowhole Air enters the lungs through the blowhole and muscles keep it covered under the water.
Echolocation over eye Orcas have excellent eyesight, but echolocation is their best navigation tool. Pectoral fin The fins on either side are used to touch and steer.
Fluke An important part to the killer whale’s vital hunting manoeuvres, the tail propels the whale through the water at top speed, enabling it to also balance as it floats upright, peering cautiously.
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40 sharp teeth These are positioned so that the upper teeth fall into the gaps of the lower set, locking prey in place so killers can drag their victim underwater.
Killer whales
Sharp senses Orcas use echolocation as a means of navigation, hunting and communication, by emitting high-frequency clicks under the water Emitting clicks The orca emits short pulses of sounds called clicks and when these sound waves connect with an object, they bounce back. In communication Orcas also use echolocation to communicate and each pod has its own unique sound that it uses when members interact.
Making sound waves Sound travels faster and farther underwater than it does in air, but the killer whale’s sensory system enables it to decipher the different echoes.
Listening for echoes These echoes enable the killer whale to detect prey, but some fish are able to hear the clicks and escape with early warning.
Orcas in numbers 34 15-18 5-30 months mph
A killer whale swimming at full power can reach this incredible top speed
The gestation period for orca mothers is twice that of a human
90
yrs
Some female orcas can reach this ripe old age in the wild
Orca pods can consist of many members hunting and migrating as one
of which can grow larger than three double-decker buses! However, it’s not just a formidable body structure – designed to propel them through the water at speeds of 50 kilometres (30 miles) per hour – that enables orcas to bring down such large prey. It’s their minds that make them true killers. Working as a team, orcas adopt a manoeuvre known as spy-hopping, where the creatures swim vertically to the surface and poke their heads above water to take a good look at their surroundings. For at least 30 seconds they use their tail (or fluke) for balance and pectoral flippers on either side to keep afloat, like a human uses their arms to tread water. They’ll be hoping to spot a seal, although these cute-looking animals are armed with sharp claws and teeth – the killer whales know this, so will always aim to grab the seal’s tail to be on the safe side. Before the chase even begins, the orcas gang up on the seal that will be resting on an ice floe, thinking it’s probably
50 9.8 15 227
thousand The estimated metres population of The top length of killer whales
a killer whale
yrs
Age at which female killer whales mature
kilos
BELOW The whales peek above water to check for prey, then jump at an impressive speed to catch one
Amount an orca eats each day
safer on the land than in the water. Working together, the whales duck under the surface and swim side by side towards their quarry. At the last moment, they quickly change direction and unleash an all-mighty wave that crashes over the block of ice and knocks the prey clean into the water. By now the seal is fully aware that it’s under siege and there’s always a chance it can escape by clambering aboard another ice floe. The orcas will be doing everything they can to prevent this, by using their immense bodies to create underwater turbulence and blowing bubbles to encourage the seal to dart into open water where it doesn’t stand a chance against the pod. From this point on it’s a game of catch-the-seal-
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Lethal hunting techniques Orcas make formidable predators thanks to their ability to operate as a team and make use of methods that are masterstrokes of whale ingenuity
Team work Seals have excellent hearing, so the whales remain silent before going in for the kill. They remain in parallel formation and charge towards the ice floe where a seal is resting.
Spy-hopping Killer whales are the only marine mammal known to locate and capture prey out of the water by spy-hopping – rising vertically above the surface to see what’s there.
Catch of the day A seal’s teeth are sharp, so the whales will avoid getting hurt in the process of capturing their meal by aiming for the tail. They will then drag their quarry under the water to drown it, before divvying up portions among the pod.
Making killer waves Pumping their tails (flukes), the whales create an almighty wave that crashes over the ice floe and washes the seal into the water. They continue to work as a team to confuse the seal by blowing bubbles and creating turbulence.
“The way the killers hunt is a prime example of their intelligence and fascinating minds.” by-its-tail, and once they do they will drag the creature to the ocean’s depths and drown it. Unlike the seal, the killer whale can hold its breath for long periods of time. The way the killers hunt is a prime example of their intelligence and fascinating minds. A family that forages together, feeds together, but seals only make modest meals. If the opportunity arises, the orcas will hunt other whales, such as the Antarctic minke. These solitary animals easily match the size of a killer whale, which is still small by whale standards, but provides a hearty feast for a hungry pod. When the minke whale is within sight, the black-and-white hunters head towards the creature at top speed and draw level. They position themselves with one on either side of the victim, blocking any means of escape, and pursue it for hours on end.
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The minke’s only real defence is its sheer endurance, but the killer whales are genius hunters. The outriders replace one another in relays, keeping up momentum. With many killers and only one minke, the latter inevitably tires. The orcas then move in for the kill, biting and attempting to flip the whale over. By keeping its blowhole submerged, they can effectively drown the minke before devouring it. The whales are so expertly organised that they have been compared to wolf packs, and this fierce reputation has endured since ancient times, giving them their scientific name Orcinus orca. The name comes from the mythological Orcus – the Roman god of death and the underworld. Still, there’s no record of this sea-bound behemoth ever killing a human in the wild. In captivity, however, it’s a different story.
Killer whales
Smart moves Orcas display complex behaviour that shows just how intelligent they are
Emotion Male killer whales will remain with their mothers all their lives, which can be up to 50 years! Families of orcas are so close that capturing one is akin to kidnapping a human. Researchers have noted that they exhibit what seems like grieving when a member of the pod dies, causing others to become withdrawn.
Speech One of the most amazing discoveries is that different pods have their own unique dialects. They make these sounds more frequently when a calf has been born so that the youngster can learn, just like human parents teach their children to speak. It’s thought that these advanced dialects create a group identity and also prevents inbreeding.
Social structure
“A family that forages together, feeds together, but seals only make modest meals”
These incredibly social animals travel in pods that can consist of up to four generations. A social hierarchy exists within groups of killer whales, with the females being more dominant. Signs of establishing authority within a pod include slapping their tails against the water, as well as snapping their jaws.
Problem solving The average orca will eat over 550 pounds (250 kilograms) of food a day, working as a team to successfully catch their prey. This could be flanking a minke whale on either side and regularly swapping places, like a relay race, or charging an ice block in unison to cause a wave to wash their prey into the water.
Playfulness Orcas have a great sense of humour and there’s plenty of video footage to back this up. You can watch them playing with balls of ice and even mimicking the sound of a motor boat – a surprisingly accurate impression. Other anecdotes include orcas moving objects that humans are trying to reach and they’ve even been known to play with their food, letting it slip away but always catching the prey in the end.
ABOVE Pods are led by female matriarchs, who pass on hunting skills to their offspring and family members
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Sharks & Ocean Predators Quick questions with an expert Name: Erich Hoyt Role: Whale and dolphin researcher Organisation: Research fellow with Whale and Dolphin Conservation UK You were working as a sound later, we are still learning every For your book, Orca: The engineer to record orcas’ day about this amazing and Whale Called Killer, you voices before dedicating your beautiful species. spent time living among pods career to the scientific study of killer whales off northern and conservation of them. They’ve been called wolves of Vancouver Island, Canada. Can you describe that first the sea and killing demons. Could you share some of your encounter with a killer whale? What did orcas do to earn such experiences? I learned some of the orca frightening names? I spent ten summers with the sounds on an electronic They are predators at the top same pods of killer whales, synthesizer and on one of the of the food chain. From Greek getting to know them as first times we met the killer and Roman times orcas were individuals and families. whales I played them my seen hunting together in pods, Some were very stand-offish, imitation of one of their calls. killing and eating larger whale while others such as two Aer a moment’s hesitation, species. That would have older matriarchs, Nicola and two or three whales answered earned them some of those Stubbs, were very friendly and in unison with a perfect mimic names. At the same time, tolerant of our presence. There of my sound. Later we realised however, in native cultures were a couple of hyperactive that since the young whales living around the Pacific rim, youngsters in the early years are born without the sounds orcas were highly respected that we called The Twins. They of the pod, that mimicry is an for their hunting ability. Some weren’t actually twins but hung important method for learning cultures saw them as their around together and used to what turned out to be vocal ancestors and put them on play around our boat. They dialects that were unique to their totem poles to be admired would also come by our camp each pod. Now, many years and respected. at night and splash in the near-
“Orcas show high levels of emotional capacity, self-awareness and problemsolving skills that show a superior intellect” BELOW The family structures within pods is integral to killer whale survival, and is a big indicator of their huge intelligence
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Since the 1970s there have been attacks on nearly two dozen people worldwide, but opinion is divided over whether these are accidents or deliberate attacks. Orca expert and neuroscientist Lori Marino doesn’t underestimate this animal’s intelligence: “I’m not trying to second-guess what was in this particular whale’s mind,” she told Orlando Sentinel, referring to a recent fatality in an aquatic park. “Certainly, if we are talking about whether killer whales have the wherewithal and the cognitive capacity to intentionally strike out at someone, or to be angry, or to really know what they are doing, I would have to say the answer they do.” Researchers agree that orcas exhibit high levels of emotional capacity, selfawareness and problem-solving skills that hint at a superior intellect. Fishermen tell stories of Alaskan killer whales stealing fish from longlines and, when the men started positioning their boats miles apart and taking turns to reel in the haul, the orcas split into two groups. Footage of killer whales playing with chunks of ice when a man tossed a snow ball in their direction shows
shore waters. We truly felt a part of their world. As a senior research fellow with Whale and Dolphin Conservation UK, what can people do to help ensure the continued survival of this amazing animal? Join a whale-conservation group, adopt an orca, a dolphin or a whale, volunteer, refuse to go to SeaWorld, read all you can about the ocean. A good starting point is the website Whales.org or its Facebook page. Read up, follow them and get to know the whale world! Orca: The Whale Called Killer by Erich Hoyt is digitally available on Kindle. For more information, visit www. erichhoytbooks.com.
intelligence in the form of recreation, too. In fact, the whales are well known for their playfulness and curiosity. They’re also often observed leaping out of the ocean and landing on their side or back with a colossal splash, known as breaching, and lob-tailing, which involves slapping the tail flukes on the water’s surface. These displays of water acrobatics can be a sign the killer whales are courting, relieving an itch or purely playing. Mothers dedicate a lot of time to the latter, investing so much time in being good parents that they only have a calf every five years or so. This is also due to a lengthy gestation period of 16 to 18 months – the longest of any whale. This is surprising since they are by no means the largest mammal of the ocean, but it takes time to develop such a large brain – the second largest of any animal on the planet. Fascinatingly, killer whales also experience the menopause just like human females do. They are one of only three species that continue to live long after they have stopped reproducing, which means the mothers can devote the rest of their lives to taking care of their offspring and grandchildren. The reason for this unusual evolutionary trait is believed to lie in their social structure, where mothers take a leading role. Each member of the pod pitches in to raise the young and the bonds between them are akin to human families. When a calf dies, for example, mothers have been witnessed carrying their baby with their heads and when the calf slips, the family dives to retrieve the body. They appear to become withdrawn, go off their food and regularly return to the spot where their family member died. As humans, it’s difficult for us to avoid projecting our own feelings onto an animal, but it seems that killer whales – and other highly intelligent species such as bottlenose dolphins and elephants – mourn their dead. It’s heartbreaking, but this emotional intelligence is just another indication of how astoundingly clever these animals really are.
Killer whales BELOW An orca dives back into the water aer breaching, which is thought to be part of the courting process
© Corbis; Getty; FLPA; NaturePL.com; Thinkstock; Dan Cole; Peter Scott; Christopher Michael
“Each member of the pod pitches in to raise their young and the bonds between them are akin to human families”
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Sharks & Ocean Predators
18Fantastic facts Killer whales Killer by name, killer by nature? It’s time to find out the truth about the whale that isn’t a whale, from which even great whites make a hasty retreat
Killer whales are dolphins Despite their name, killer whales are in fact the largest members of the dolphin, or delphinidae family. Though just to confuse matters further, all dolphins fall under the order of infraorder odontoceti or toothed whales!
They go by many names Today, they are most commonly known as orcas and killer whales, but their Latin name orcinus orca is thought to translate in modern terms to ‘demon from hell’. Across the centuries and different cultures, they have also been called asesinas de ballenas, which translates as whale killers in Spanish, zwaardwalvis, meaning sword whale in Dutch and shachi, the Japanese term for tiger and fish.
Excluding humans, no mammal’s range is as widespread as the orca’s. They are found in all of Earth’s oceans, from the equator to both poles Just behind the dorsal fin, killer whales have a grey patch known as the saddle, or cape. Varying in shape and colouration between individuals and easily spotted from the surface, this is often used along with the fin to identify individuals Male orcas are slightly larger than females and their dorsal fin is an indicator of gender
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Family matters to orcas A mother cares for her calf for one to two years. Even once they have matured, most killer whales will stay in the same pod as their mother for the rest of their lives.
Their closest relatives are actually hippos Despite acting more like wolves, orcas share a common ancestor with the hippopotamus, a prehistoric pig-like animal called indohyus that lived around 48 million years ago.
They are the fastest marine mammals These apex predators are the cheetahs of the sea. In 1958 a bull killer whale was clocked travelling at 55.5 kilometres (34.5 miles) per hour in the Pacific Ocean.
Killer whales They are great team players Killer whales form close-knit bonds with their fellow pod members, which on average tends to number around 40 individuals. They do everything together, spending their time travelling in search of food, playing, hunting and resting. They have developed some ingenious collaborative tactics for capturing prey, including taking turns to chase down a victim until it’s exhausted and creating waves to knock stranded animals off ice floes.
They can hunt just like bats Killer whales can detect their next meal in murky water or even at night by making clicking sounds and listening for the resulting echoes. Studies have shown they can even pinpoint specific prey using this technique. They use this same echolocation ability to navigate. Unlike bats, orcas also have acute vision, so they can use both senses individually or together, depending on the environmental conditions.
Every pod has its own dialect Very social creatures, killer whales use a complex series of whistles, pulsed calls and clicks to communicate with one another. There are similarities in signals across all groups, but nevertheless, scientists have detected distinct variations, not just between regions but even from pod to pod.
They listen through their jaws
Killer whales will sometimes eat sharks
Although the orca’s physical ears are two small holes located just below the eyes, several parts of the head contribute to its hearing. It targets clicks in a beam from the bump on its head called the melon, then perceives the majority of the returning echoes via its fat-filled lower jawbone, through which the vibrations pass to the inner ears.
Sharks usually sit quite comfortably at the top of the food chain, but even they need to take care if killer whales are around. In 2014, marine biologists captured a video of an orca pod harrying a tiger shark until it flipped over. There have even been sightings of orcas taking on great whites! Black and white is perfect camouflage The killer whale’s patchy markings have evolved as a form of disruptive colouration, masking their true outline to deceive prey into thinking they are no threat, until it’s too late. They are primarily black on their backs and white on their bellies, which also makes them harder to spot from either above or below.
They also eat moose It might not seem the most likely of prey for a marine mammal, but moose and deer in Alaska have fallen victim to orcas when swimming between islands and the mainland.
They’re not afraid to venture onto land
Often referred to as blackfish, killer whales appear in many legends and fables in Native American cultures. Some believe orcas were the reincarnated spirits of young tribesmen lost at sea.
© Alamy; Ardea; Dreamstime; Thinkstock
Orcas are very sacred to many Native American tribes
Killer whales can go to great lengths to catch their next meal, even intentionally hurling themselves out of the water and beaching themselves to catch a sea lion or penguin lingering temptingly close to the waterline. Typically performing this trick at high tide, they let the waves carry them back into the sea, though now and then it can backfire and they get stranded. Their favourite delicacy is tongue Sometimes killer whales will take on bigger whales, even the largest animal ever to live – the blue whale. Only able to eat so much in one sitting, they generally dine on the tongue and lips and leave the rest. That said, in the case of the blue whale this is no small snack, as its tongue is big enough to fit a line of 50 people!
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Sharks & Ocean Predators
Ocean’s brainiacs
Killer whales Killer whales have the second-largest brains among ocean dwellers but what do they use it for? With their instantly recognisable colouring and huge triangle-shaped dorsal fin – up to 1.8-metre (six-foot) high in some males – orcas look every inch the predator. These animals are classed as dolphins, and have incredibly clever methods of communication that they use during hunting and feeding. Often found living in family pods, orcas like to eat penguins and seals. They hunt as a close-knit group to surround and confuse prey, taking it in
KILLER WHALE Orcinus orca Class Mammalia
Territory Found in all the world’s oceans Diet Seals, sea lions, penguins Lifespan (in wild) 50-80 years Adult weight Up to 5,400kg (11,900lb) Conservation Status
DATA DEFICIENT
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turns often to get a bite. These whales have even been known to rock floating ice from beneath to wash seals off their perches and into a hungry mouth! Arctic and Antarctic life is easy for an orca – thick layers of blubber help to keep out the chill and orcas are constantly active. Killer whales spend a lot of time at the surface, and engage in plenty of spyhopping – where the whale sticks its head above the surface – breaching and tail-splashing.
Killer whales
What’s in a name? The name ‘orca’ comes from the whale’s Latin name ‘Orcinus orca’, but many people know the orca as the ‘killer whale’. The orca’s stealthy hunting tactics alongside its large appetite certainly contributes to this name! The Spanish sometimes refer to the orcas as ‘ballena asesina’, meaning ‘assassin whale’ and it’s thought that whalers named orcas ‘whale killers’ when they witnessed them hunting other whale species. ‘Killer whale’ seems to have been adopted over time.
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Sharks & Ocean Predators
18 Amazing facts Seals
From the gaseous blood of an elephant seal to their four-legged ancestors, this group of marine carnivores has a lot of secrets that we’re gradually uncovering The deepest-diving seals are elephant seals, reaching depths of 2,400m (7,835ft). That’s like swimming 50 lengths of an Olympic swimming pool without taking a single breath. Pups wait to be waterproof Most newborn seal pups are born with silky so white fur and spent their first four to six weeks of their lives on land. During this time, their layer of insulating blubber thickens and their baby fluff is replaced by waterproof fur.
Seals evolved in the Arctic from four-legged mammals around 30 million years ago. Their closest relatives on land are otters, dogs and bears. 84
Harbour seals have unique whiskers. They’re twisted in an asymmetric pattern which allows the animals to detect the trail of a fish 35 seconds after it has passed the seal.
Seals Seals can live for more than 45 years, with females typically having a longer life span than males The southern elephant seal is the largest of all pinnipeds, weighing up to a massive 3,855kg (8,500lb) Crabeater seals are the most abundant seal species, with an estimated 75 million living on the planet California sea lions are the fastest member of the family and are able to swim at 40km/h (25mph) in short ‘sprinting’ bursts Mothers produce 50 per cent fat milk Female seals produce milk that is 50 per cent fat to feed their newborns. By guzzling this fatty milk, seal pups are able to gain 2kg (5lb) every day until they are large enough to learn to hunt.
Seals blow bubbles Getting the attention of a female is a challenge for male seals, and they use sounds to tell their neighbours that they are the best seal around. Rather than barking like a sea lion, seals make growling sounds to communicate about their quality as a mate and to warn other males away. Creating loud splashes by slapping the water’s surface and blowing bubbles while submerged also attract females to a prime male seal.
Seals have a higher hearing threshold than humans, meaning they can hear higher-pitched sounds than we can
An elephant seal’s blood has an unusually high concentration of carbon-monoxide gas that could help control their buoyancy and protect their lungs. Monk seals are violent With a combination of massive weight and the instinct to mate, male monk seals injure and even occasionally kill females when trying to mate with them. These seals mob females while their blood is surging with testosterone, unfortunately sometimes leaving the females injured or even killed.
There are 33 members of the pinniped family and these are split up into three groups; the true seals that include harp and leopard seals; the eared seal group with sea lions and fur seals; and walruses that make up the third group
© Thinkstock, Dreamsitme
Elephant seals can hold their breath for two hours Weddell seals can hold their breath for 80 minutes, only surfacing when they spot a hole in the Antarctic ice above them. The true masters are elephant seals that can hold their breath for up to two hours while diving.
Ringed seals are the smallest Ringed seals are the smallest member of the family with body lengths of just over 1m (3), with the smallest weighing only 50kg (110lb). These are the most common seals in the Arctic and make up more than 60 per cent of a polar bear’s diet.
Female seals flock to the strongest male seals during mating season. These groups of females are called harems, and a single male seal gets to have his choice of up to 50 of these females in any given mating season
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Sharks & Ocean Predators
Spotters’ guide
Grey seals
Discover where you might get a chance to find these incredible seal species The charismatic creature is one of the rarest seal species in the world, but it’s easy to catch a glimpse when you know where to look. You’ll most likely find them on rocky islands and coasts around the UK, since Britain plays host to half the world’s grey seal population. Some of the best seal-watching spots are Blakeney in Norfolk, the Orkney Islands and Cornwall. The latter offers boat trips in Newquay Harbour, as well as being home to the Cornish Seal Sanctuary where you can see rescued seals that have been brought in for emergency treatment. The chances are that you will be able to see these underwater horses all year round, as they have plenty of excuses to come ashore (known as hauling-out). Grey seals will leave the water to mate during their annual moult in the spring, to bear pups in the autumn, or even just to digest their food. Some of the best sites require boat access, so you should always seek a Wildlife Safe (WiSe) operator, who will have been trained in minimising
Get out and see them Find a seal-spotting trip Phoenix Boat Trips
www.phoenix-boat-trips.co.uk 07703 168097 Operating in Moray Firth, Scotland, this trip offers views of a seal colony near Ardersier. Monomoy Island Ferry
www.monomoyislandferry.com 508-237-0420 Operating from Chatham, Massachusetts, USA, this trip offers tours around the Monomoy Islands. Blakeney Point Seal Trips
www.blakeneypointsealtrips.co.uk 01263 740 792 A voyage through the historic seaport of Blakeney Harbour on the North Norfolk Coast. Sea.fari
www.seafari.co.uk 0131 331 4857 Hop on board the 55-passenger catamaran into North Berwick in Scotland. Pre-booking is essential. Sealife
www.seawildlife.co.uk 01445 781729 Set sail on this glass-bottom boat trip that promises daily sightings of the common and grey seals.
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disturbance to marine wildlife. You can also help avoid causing a disturbance by wearing low-visibility clothing because, although seals see in black-and-white, any bright colours will stand out. It’s also sensible to wear waterproofs and wrap up warm, since coastal winds can cause a chill. Fortunately for seals, they have a thick layer of blubber and waterproof fur that keeps them insulated. You’ll find them in the United States too, near Cape Cod, Massachusetts, or even New York and New Jersey. However, these waters are also home to the grey seals’ natural predator, the great white shark, so if you’re seal-spotting stateside you might see more than you bargained for. They can also be found across North America’s east coast, and Europe.
GREY SEAL Halichoerus grypus Class Mammalia
Territory North Atlantic Ocean Diet Carnivore Lifespan 25-35 years Adult weight 220kg / 485lbs Conservation Status
LEAST CONCERN
Grey seals The grey seal is found on both shores of the North Atlantic Ocean
“Seals have a thick layer of blubber and waterproof fur that keeps them insulated”
ABOVE Seal watching boat approaches a sand bar in Blakeney, Norfolk, UK
What’s the difference between a seal and a sea lion?
They’re oen confused, but these two sea predators are very different
Ears Sea lions have external ear flaps on either side of their head, whereas true seals only have ear openings without flaps. Seals have lost their ear flaps over time to become more streamlined when swimming. Swimming ability Seals have evolved to be more streamlined than sea lions because they spend more time in water. While sea lions can dive to depths of 275 metres (900 feet), seals can reach depths of 4,100 metres (13,450 feet).
Sounds Sea lions bark and are notoriously noisy, but seals are much less vocal. Seals do make a variety of sounds but these are mostly used to attract mates.
Steering Sea lions steer with their long front flippers, whereas seals change direction with their back flippers. The bones in a seal’s back flippers are extremely long and strong, and they propel themselves forward using only their back flippers.
Back flippers A sea lion’s back flippers can rotate outwards to aid walking, but a seal’s back flippers are fixed facing backwards. Because of this, sea lions are better at escaping predators on land than seals.
Whiskers Both seals and sea lions use their whiskers to detect vibrations, helping them find food and sense predators. Although they serve the same function, sea lions have straight whiskers and seal whiskers are crimped.
Land movement Seals wriggle forwards on their bellies when moving around on land, whereas sea lions can walk upright with their flippers. This wriggling action helps seals move across ice faster than a human could run.
Front flippers Seals have short, furry flippers with claws on each digit. The front flippers of a sea lion are long, hairless and without claws. Because they are more efficient walkers, sea lions don’t need claws to help drag their bodies.
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© Photoshot; Getty. Thinkstock
Where can you see them?
Sharks & Ocean Predators
Endangered
Galápagos sea lion GALÁPAGOS SEA LION Zalophus wollebaeki Class Mammalia
Territory Galápagos Islands Diet Carnivore Lifespan 20 years Adult weight 50-250kg / 110-550lbs Conservation status
ENDANGERED
While this magnificent mammal lives in a reserve protected by the Ecuadorian National Park Authority, its population fluctuates wildly and since the Sixties it has decreased from 50,000 to an all-time low of 14,000. Violent storms, pollution, limited food and human interaction have put a significant dent in this animal’s numbers. Despite being an experienced hunter and predator, a penchant for wandering far out into the ocean and an innate curiosity towards humans, often lead the rare creatures into danger
Why it’s endangered Pollution Galápagos sea lions are particularly vulnerable to the pollutants that inevitably find their way into the sea. These creatures are naturally curious animals, so they often see floating plastics as toys or objects for them to play with, which unfortunately are easily swallowed. More-serious chemical dangers also lurk in the form of toxic pesticides such as DDT.
Lack of food Sardines aren’t just a Galápagos sea lion’s primary food source, they’re also high up on a fisherman’s hit list. What a seal lion wants to eat, so do humans. As such, overfishing has depleted this resource and climate change hasn’t helped. The Pacific El Niño storm, which revitalises the seas and increases food available, has become increasingly irregular in recent years.
Disease Through a genetic twist, Galápagos sea lions are particularly vulnerable to diseases that also affect dogs and domestic animals. Because of their unique relationship with humans on the Islands, their forays onto the mainland take them into the streets and parks, as well as the beaches. This means they frequently come into contact with other animals that spread illness.
Discover more… WWW.GALAPAGOSPARK.ORG Responsible tourism to the Galápagos Islands is encouraged: the park authority limits tourist numbers and access to certain areas, so by visiting the sea lion’s natural habitat, within the rules, you can help secure its future.
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Galápagos sea lions Decreasing numbers Only a fih of the Galápagos sea lion population exists today
Galápagos
1914
Estimated number of animals left today
Estimated total animal population 100 years ago
14,000
70,000
Where they live As its name suggests, the Galápagos sea lion is a species that lives exclusively on the rocks and in the ocean around the volcanic Galápagos Islands, just off the Ecuadorian coast. It also lives in smaller numbers on the nearby Isla de la Plata. Galápagos Islands and Isla de la Plata territory in 2014
The Galápagos National Park, or Parque Nacional Galápagos as it’s known in its native tongue, works towards the preservation of the natural wildlife of this unique island group. As a UNESCO World Heritage Site and historic location of Darwin’s famous 19thcentury voyage, the Galápagos Islands are a natural wonder that Parque Nacional Galápagos is serious about preserving. Initially, the animals in this area didn’t fear humans like the rest of the world’s animals do. However, in recent years there’s been an increase in sea lion attacks from humans, as well as accidental fishing gear entanglements. As such, a program was launched to protect the species and help them better cohabit with the human population. The gem in the collection of unique species, which has evolved in isolation over thousands of years in the area, is the Galápagos sea lion. Part of the national park’s effort to protect this animal is a regular, detailed population census. With the data recorded by the census, the park officials can follow up with a sample and analysis of the disease prevalent in the population. They can also manage nurseries and educate local schoolchildren about the importance of conservation and protection for the creatures. For more information and to arrange a visit to the Islands, go to www.galapagospark.org.
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© IMAGEBROKER,NORBERT PROBST/Imagebroker/FLPA
Island paradise protection
Sharks & Ocean Predators
Meet the family
Whales GRAY WHALE Eschrichtius robustus Class Mammalia
Territory Coastal North Pacific Diet Amphipods and other small sea floor dwellers Lifespan 50-60 years Adult weight 35,000kg / 77,162lbs Conservation status
LEAST CONCERN
Meet six incredible members of the whale super family
Gray whale A haven for tiny travelling parasites
Along for the ride Parasites and organisms live on gray whales’ bodies, giving them a distinctive rocklike look.
Known for their distinctive look, these big ocean beasts are covered in parasites and organisms that make them look a lot like an ocean rock. Unusually, the whale uses its snout to dislodge small creatures from the sea floor and sieves them through comb-like filter plates in its upper jaw known as baleen. Once used to make corsets and umbrellas, gray whale baleen is tough but flexible and can grow up to 50 centimetres (19.7 inches) long. While following their lengthy migration, a gray whale can swim some 20,000 kilometres (12,427 miles) to Alaskan waters and then back to the Mexican coast.
Filter feeder Using baleen plates to seive zooplankton and small fish, Sei whales consume up to 900 kilograms (2,000 pounds) of food every day.
Distinctive spout The sei look similar to blue and finback whales, except they’re smaller and have a curved dorsal fin with a dark underside. They are oen noticeable by the inverted V shape of the spout.
SEI WHALE Balaenoptera borealis Class Mammalia
Territory Atlantic and Pacific Oceans Diet Zooplankton and small fish Lifespan 70 years Adult weight 28,000kg / 61,729lbs Conservation status
ENDANGERED
Sei whale
The largest brain Sperm whales have the largest brain of all animals on Earth. Weighing 9kg (20lbs), it’s about six times heavier than a human’s brain.
A speedy cetacean with a healthy appetite for plankton A filter feeder that uses its baleen plates to sieve zooplankton and small fish out of the water, sei whales can consume up to 900 kilograms (2,000 pounds) of food every day, competing with other whales, basking sharks and large fish such as herring. Sei prefer temperate waters, although they can be found in seas all over the world, including tropical, Arctic and Antarctic oceans. They usually travel alone or in small pods with less than five members and can cruise at speeds of 26 kilometres (16 miles) per hour, up to a maximum of 50 kilometres (31 miles) per hour. They have become a more popular target for whalers as the populations of blue and finback whales diminish.
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SPERM WHALE Physeter macrocephalus Class Mammalia
Territory All oceans Diet Carnivore Lifespan 50 to 70 years Adult weight 41,000kg / 90,390lbs Conservation status
VULNERABLE
Sperm whale
The giant of the ocean with a sizeable brain to match With the biggest brain of any animal on Earth, the sperm whale is an incredible creature that can eat an enormous quantity of food a day. The whale is named after the spermaceti oil that it produces in an organ of the same name, within its huge box-like head. It’s thought that this fluid, which hardens to wax when cold, helps the whale regulate its buoyancy. This comes in useful when the whale dives to the depths of the ocean to feed on things like giant squid, where they can hold their breath for up to 90 minutes at a time.
Whales Unique markings Minke whales are distinguished by a pointy, triangular snout and white bands around their fins.
Minke whale
The baby of the filter feeders The second smallest baleen whale, the minke, measures on average 6.9 metres (22.6 feet). Distinguishable from other whales by a white band on each flipper, minke whales have up to 360 baleen plates either side of their mouths to help feed. They’re a dark, near-black colour with a white underbelly. The whale takes three to five intakes of breath and dives deep into the water for up to 20 minutes at a time. Reaching speeds of around 38 kilometres (24 miles) per hour, they sieve through the water for plankton and krill, catching the occasional small fish and sometimes giving chase to sardines. They habituate all the oceans except polar ones and swim in groups of just a few individuals.
MINKE WHALE Balaenoptera acutorostrata Class Mammalia
Territory: All oceans bar polar Diet Plankton and small fish Lifespan 30-50 years Adult weight 9,200kg / 20,000lbs Conservation status
LEAST CONCERN
Most unusual Narwhal Monodon monoceros A member of the Monodontidae family (a group of toothed whales), narwhal are most recognised for the tusk that grows up to 2.7 metres (8.9 feet) long. Nicknamed the unicorn of the sea, its tusk is actually the more prominent of two teeth of the male of the species (although females can grow a small tusk too). The tusk grows through the upper lip and some believe it’s predominantly to impress females during mating rituals or to battle off rival males. The pale-coloured creatures travel in groups of 15 to 20, feeding mainly on fish and shrimp.
Natural filter 35 grooves on the throat enable the humpback to gulp and filter water by extending the throat.
HUMPBACK WHALE
The song of the humpback These whales are known for the incredible way in which they communicate. Their amazing songs can be heard across massive distances.
Megaptera novaeangliae Class Mammalia
LEAST CONCERN
Humpback whale The oceanic composers
A remarkable creature, the humpback is another colossal baleen whale of the ocean. It has up to 35 grooves on its throat all the way from the chin to the navel. It can expand the throat to enable huge intakes of water to then filter in food such as plankton and krill. Humpbacks are renowned for performing amazing songs that can be heard over great distances. Thought to be great methods of communication, particularly to attract mates, the songs are made up of moans, howls, cries and the humpback’s complex noises can often last hours.
© Thinkstock; FLPA
Territory All oceans Diet Krill and small fish Lifespan 45-50 years Adult weight 27,000kg / 59,525lbs Conservation status
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Sharks & Ocean Predators
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Humpback whales
SONGS OF THE
HUMPBACK These melodic symphonies of the sea are among wildlife’s greatest wonders. Exactly why tuneful whale composers create these underwater serenades is one of the biggest mysteries of the deep
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Sharks & Ocean Predators There was once a time when the oceans were thought to be vast expanses of virtual silence, but we gradually began to realise that our planet’s water bodies were a cacophony of aquatic noise. When biologist Roger Payne discovered the song of the humpback in the late 1960s, everything we thought we knew changed. Yet, over four decades on, we still don’t know the full story and the whales are keeping scientists guessing. Humpbacks are large whales, reaching up to 15 metres (50 feet) in length. These majestic beasts have long, tapered bodies with elongated pectoral fins and a short dorsal fin, ending in a large fluked tail. Their knobbly heads have huge jaws to help with their filter-feeding method of eating. “They’re found in all oceans, but not necessarily all of the time, because they’re migratory,” explains Regina Asmutis-Silvia, executive director of the North American Whale and Dolphin Conservation Society. “They tend to go to higher latitudes to feed, then to the more-temperate tropical waters for breeding.” For whales that cruise across whole oceans every year, tracking them down for study can be tricky. This is one reason why we don’t know much about their social structures, or their amazing methods of communication. Like most cetaceans (the group of animals containing whales and dolphins), humpbacks make grunts, whines and shrieks. However, their songs have been dubbed as the most-complex vocalisations in the animal kingdom and are truly captivating. “[Humpback] song is made up of many sounds that the whales arrange into long, complex songs each year,” says Dr Ellen Garland, from the National Marine Mammal Laboratory. “It’s an acoustic display that’s produced by males. We aren’t quite sure whether it’s for attracting
mates or repelling rivals, but it has something to do with mating.” The noises that the whales string into their eerie performances are generated as they force air through their nasal cavities “sort of like a bagpipe”, Asmutis-Silvia explains. “They produce a lowfrequency sound and the lower the sound, the further it will travel, so they can conceivably communicate with other whales that are tens if not hundreds of miles from them,” she continues. “It’s kind of like a mobile phone – you can stay connected with your family even when you can’t see them.” The whales’ keen hearing means the animals can be in touch across huge expanses of ocean. So, why do the males sing at all? “It was thought to happen only in the breeding area or maybe the shoulder seasons,” Asmutis-Silvia continues. “But it seems to be happening year-round, so it has some function that isn’t exclusive to breeding. It may be a contact call – it may have different purposes at different locations as well.” When the males do sing, they seem to find one another, as Asmutis-Silvia goes on: “[A whale] will
ABOVE Humpback whales adopt a very specific stance before beginning their serenades BELOW The underwater songs have set patterns, but to impress females, males will oen vary their tunes
HUMPBACK WHALE Megaptera novaeangliae Class Mammalia
Territory Found in all the world’s oceans Diet krill, plankton, small fish Lifespan 45-50 years Adult weight 40 tons Conservation status
LEAST CONCERN
“Their songs have been dubbed as the mostcomplex vocalisations in the animal kingdom” 94
Humpback whales
How do whales talk? Humpbacks use a variety of methods to get in touch with one another, including body language, as well as a range of clicks, grunts and whistles
Breaching on the surface Whales may breach to show dominance or for fun. The breach’s intense sound could communicate the location and size of the whale.
The singing stance Males oen adopt this stance to sing. They hang in the water with their heads down, tails bent and flippers out to the sides.
Whale body language Gestures such as tail slaps or lunging are also methods whereby males can show off during the mating season.
Other vocal noises Aside from singing, humpbacks are known to vocalise socially with other noises, including whoops, barks, grunts and groans.
Potential echolocation noises Whales feeding at night have been seen making low clicks and buzzes, similar to noises made by toothed whales during echolocation.
sing for a period of time and it seems that at the end of that singing it’s the males that will find one another and make contact. The song is so melodic and it’s so eerie. It’s beautiful and it seems peaceful in some respects. There aren’t a lot of physical altercations between these males once they find one another. The actual activity of mating is physical, but that’s not where the songs are happening.” The males that sing these beautiful harmonies will hang in the water column, with their heads down and flippers out, repeating phrases and stringing them together into recognisable patterns that form the songs for up to hours at a time. “What is interesting is that the males in a population all sing the same song as one another, but the pattern of the song changes with time,” explains Dr Garland. “All the males make the same changes, so they keep singing the same pattern as one another even though that pattern is changing. We think of it as a cultural trait rather than something that’s genetic.” This discovery of a culture within humpback populations was made by a team including Dr Garland. They studied the songs recorded from six neighbouring humpback populations from across the south-western Pacific ocean, for over a decade. She made some fascinating findings. “We found songs moved eastwards from one population to the next,” Dr Garland says. “The movement was like a series of cultural ripples spreading across the region.”
But how does this happen? Dr Garland and her team have figured out at least a few answers: “Usually the song contains some older material from the previous year and then some exciting new stuff,” she begins. “It would be like splicing an old Beatles song with U2. Occasionally they start singing a brand-new song. So in essence all males sing the same thing at the same time but what they sing changes either to a completely new song…”
The song of the humpback Singing oen happens when males reach breeding grounds. It may be to entice females, display dominance, or contact others.
BELOW Humpback whales will oen gather together in numbers wherever food is plentiful
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Sharks & Ocean Predators Given that the singing is most strongly (yet not exclusively) tied in with breeding amongst humpback whales, this evolution of songs may have the benefit of impressing female whales with fresh new sounds to be serenaded by, as well as infuse a bit of individuality for the male humpback. “In human society when new fashions appear, there are a few savvy people who embrace it and then everyone else quickly follows,” Dr Garland elaborates. “We think this male quest for song novelty is in the hope of being that little bit different and more-attractive to the ladies. This is then reeled in by the urge to sing the same tune, by the need to conform, which is the same as with humans when everyone wants to be the same.” Whatever the whales’ reasons for composing and performing new song material year on year, we still have so much to learn about why they vocalise in such an intricate and beautiful way. “These songs are incredible, but energetically expensive,” enthuses Asmutis-Silvia. “When you’re making a lot of noise and using up energy, you generally do it for a purpose. These songs are frequently happening in the breeding
“This evolution of songs may have the benefit of impressing female whales ”
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areas where there is very little food available, so it might serve a really important role for them to use up that energy in a place where they’re not even sure when they’re going to get their next meal. I think that’s one of the important things to remember when we’re drowning out these songs with human impacts.” Unfortunately, drowning them out we sure are. These animals are highly sensitive, but human impacts such as seismic activity, shipping noise and sonar are having a derogatory affect on these majestic creatures. A recent study showed that acoustic stress from activity over 200 kilometres (124 miles) away from the whales caused a decline in singing over a period of months. “We’re making it harder for these animals to function,” stresses Asmutis-Silvia. “A recent study from the University of Vermont explained how large whales are really the ecosystem engineers, as well as how their function and the way they work helps to fight climate change, having positive impacts on commercially valuable fishing populations. So they’re really important – not just because we like whales, but because we’re part of the ecosystem.”
Humpback whales
Underwater neighbours Although their songs are heard for miles around, the humpback isn’t by any means the biggest swimmer in the ocean Grey whale Eschrichtius robustus 14m Humpback whale
Fin whale Balaenoptera physalus 22m
Harbour porpoise Phocoena phocoena 1.6m
Minke whale Balaenoptera acutorostrata 10m Narwhal Monodon monoceros 6m (Not including tusk, which is 2m long)
Blue whale Balaenoptera musculus 30m
Bottlenose dolphin Tursiops truncatus 3m
North Pacific right whale Eubalaena japonica 17m Sperm whale Physeter macrocephalus 18m
A humpback calf jumping completely clear of the water’s surface
© Alamy, Rex Features, Thinkstock , Hendrik Gheerardyn
Killer whale Orcinus orca 9m
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The incredible journey of the
Humpback whale HUMPBACK WHALE Megaptera novaeangliae Class Mammalia
Territory All global oceans Diet Krill, plankton, small fish Lifespan 45-50 years Adult weight 40 tonnes Conservation status
LEAST CONCERN
These giants of the world’s oceans make equally massive migrations to fill their bellies, find a suitable mate and care for their young
Undertaking one of the longest mammal migrations, humpback whales make spectacular annual journeys from their cold summer feeding grounds, where they gorge on rich food, to warmer tropical coasts in the winter, where they mate and breed. The humpbacks’ magnificent acrobatic displays and complex songs can be witnessed in their distinct populations, that are found within all oceans across the Hemispheres. In summer, humpbacks spend the majority of their time feeding and
building up fat stores (blubber) to live off during winter months. The huge whales filter feed on tiny crustaceans like krill and plankton, and small fish and can eat up to 1,360 kilograms (3,000 pounds) of food per day. During the winter, humpbacks congregate and engage in mating activities. As polygynous creatures, male humpbacks exhibit competitive activities on wintering grounds. Aggressive behaviours include chasing, tail-thrashing, bodythrashing and a range of bubble and vocal displays.
“In summer, humpbacks spend the majority of their time feeding and building up fat stores”
Survival stats
10,000 km
1,360 2-3 km/h
© Thinkstock
The longest recorded mammal migration – a The average speed female humpback of the returning ventured all the way from humpbacks and Brazil to Madagascar. their calves.
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kg
The amount a humpback can eat per day during the summer, to survive the winter.
Humpback whales
Greenland sub-population This sub-population feeds as far north as west Greenland, Iceland and north Norway. It spends April through November in these highly produ ctive feeding grounds. .
North-Atlantic humpbacks Sub-populations form on feeding grounds, including the Gulf of Maine and eastern Canada. As winter approaches they make the 2,400-kilometre (1,500mile) trip to the West Indies. An Alaskan summer Humpbacks spend their summers in the cold waters off Alaska where food is abundant. They put on as much as 6,800 kilograms (15,000 pounds) to last the winter.
Pacific ocean
North America
North-east Pacific Some whales leave the feeding grounds in Alaska and head south. Sometimes older juveniles will go on ahead, while senior whales stay behind.
A tropical winter Humpbacks can make the 4,830-kilometre (3,000-mile) journey to Hawaii in as little as 36 days. The lack of predators, warm waters and underwater visibility make the islands perfect for mating and calving.
Atlantic ocean
The West Indies The most populous breeding area is along the northern coast of the Dominican Republic and includes Silver Bank marine sanctuary.
Divided populations Some of these subpopulations join the other humpbacks in the West Indies, while the rest move south to the Cape Verde islands off the western coast of Africa to breed. Africa
South America
Key Pacific population West-Atlantic population East-Atlantic population
Antarctic ocean
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Blue whale Meet the fearsome colossal whale whose throat will only swallow small prey The blue whale is not only the largest living animal; it is the largest animal ever known to have lived. Some of the dinosaurs may have come close, but these enormous mammals reach adult lengths of up to 30 metres (100 feet), and weigh over 150 tons. Even newborn calves are larger than most other full-grown animals, weighing an incredible 2.7 tons, and they grow at an astonishing rate, putting on around 90 kilograms (200 pounds) every day for the first year. On land, blue whales would be crushed by the weight of their own bodies, but suspended beneath the water, their size has been less restricted by the effect of gravity. Their internal organs are massively scaled up; their heart is the size of a car, and their tongue weighs as much as the largest living land animal, the African elephant. Their enormous size enables blue whales to make incredible low-frequency rumbling noises that can be heard up to 1,600 kilometres (1,000 miles) away, making them the loudest animals on the planet. The blue whale has a huge mouth, with a tongue large enough for 50 people to stand on it, but their throats only allow them to swallow objects the size of a beach ball. The majority of their diet is krill and like the world’s largest fish, the whale shark, the blue whale is a filter feeder. It has large fingernail-like baleen plates lining its upper jaw, and feeds by taking in a mouthful of water and then forcing it through the plates using its muscular tongue, trapping the krill. At the richest feeding times of the year, a single individual can eat up to 3.6 tons of krill every day.
Length
Weight
How big?
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1 blue whale = 130 family cars
1 blue whale = 2.5 doubledecker buses
BLUE WHALE Balaenoptera musculus Class Mammalia
Territory All oceans except the Arctic Diet Omnivore Lifespan 60-80 years Adult weight Up to 200tn Conservation Status
ENDANGERED
Dorsal fin Despite their large body size, the dorsal fin of a blue whale can be as small as 8cm (3.1in) long.
Blue whale “The blue whale is not only the largest living animal; it is the largest animal ever to have lived”
Baleen plates Over 300 baleen plates line the blue whale’s upper jaw, each measuring 1m (3.3) in length.
Small but powerful It uses its fins to help glide through the water at speeds of up to 50km/h (31mph). Ventral pleats Grooves running along the throat allow the skin to expand as the whale takes in water.
Big eyes The blue whale’s eye is over six times the size of a human’s eye, at around 15cm (6in) wide.
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Gray whale A barnacle-encrusted gray whale is trapped by an early freeze up off the coast of Alaska
© Michio Hoshino/FLPA
The gray whale is one of largest predators of the oceans at a whopping 36 tonnes. These sea-bound behemoths are usually covered in parasites that transform their hides into something resembling a weathered ocean rock rather than the skin of an animal. This doesn’t harm the animal though – in fact, it’s a symbiotic relationshop where the whale as well as the barnacle benefits. For the whale, the barnacles act as a suit of armour,
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and as the barnacles eat plankton just like the whale, they often benefit from a free meal whenever the whale swims through plankton-filled waters in order to feed. The gray whale is a baleen whale, meaning that they do not have teeth and eat through filter feeding. They use their snouts to forage for food on the seafloor, using special filterlike plates in the upper jaw to strain out the suitable nutrition.
Gray whales “The barnacles don’t harm the animal though – in fact, it’s a symbiotic relationshop where the whale as well as the barnacle benefits” GRAY WHALE Eschrichtius robustus Class Mammalia
Territory Coastal North Pacific Diet Amphipods and other small sea floor dwellers Lifespan 50-60 years Adult weight 35,000kg / 77,162lbs Conservation status
LEAST CONCERN
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Battle of the deep The underwater war between the giant squid and sperm whale With the clash of two gigantic ocean-dwelling beasts, you might expect resulting tidal waves. However, this is one grudge match that happens almost entirely in secret. Sperm whales are partial to a giant-squid supper, but the tentacled titans of the deep refuse to go down without a fight. In the murky blackness beneath the waves, away from human eyes, these amazing and all-too-elusive marine monsters battle it out for survival.
Rugged sucker scars Many sperm whales have been found with battle scars from the giant squid – their toothy suckers leave circular marks on the whales’ bodies. Sometimes these are the size of dinner plates.
Indigestible parts
Searching for a giant squid Name: Dr Edith Widder Organisation: CEO & senior scientist, Ocean Research & Conservation Association, Inc. On 3 July 2012, Dr Widder was among the first to witness the giant squid in its natural habitat “Initially we just saw its arms, which seemed to be waving in front of the camera. My lure had attracted it. It came in from the back or the side as it probed around the lure, trying to find something edible. “It was thrilling on many levels – first because so many before had tried and failed [to spot one] – but also because it was confirmation of something I’ve been saying for quite a while now: that I think we have been exploring the deep sea the wrong way. Our use of ROVs [remote operated underwater vehicles] with bright lights and noisy thrusters have been scaring animals away. “With feeding tentacles fully extended, the giant squid can be as tall as a four-storey house. It’s incredible that there are animals that big living in the ocean – probably millions of them judging by the number of giant squid beaks found in sperm whale stomachs – and we’ve never seen one alive. How many more creatures inhabit our deep oceans that we don’t even know about yet?”
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The only part of the squid that the whale cannot eat is the beak. These have often been found left in the bellies of whales.
The food of choice Sperm whales feed on other, smaller varieties of squid, so it’s thought the giant squid is a supplementary bonus to a whale’s diet.
A size match A sperm whale can grow up to 18 metres (59 feet) in length and the giant squid is an adequate competitor, with strong tentacles that stretch the squid’s body up to 12 metres (43 feet).
Battle at depth Sperm whales are known to dive to around 1,980 metres (6,500 feet) into the dark realms of the giant squid, meaning these battles take place in very deep water.
Giant squid vs sperm whale Although never observed feeding, the stomach contents of the giant squid reveal a lot about its diet
Deep-sea orange roughy
Stealing marlin from fishermen
Resorting to cannibalism
The giant squid tucks into the deep-water fish orange roughy, as well as many other different species that live deep in the depths, to supplement its diet.
Giant squid have been known to steal massive marlin from fishermen’s nets. The predatory fish are apex predators, often exceeding lengths of four metres and speeds of 60mph.
The mighty giant squid even resorts to cannibalism, where opposing squid rip off and ingest tentacles of their opponent. Amazingly, these tentacles can grow back.
Toothy suckers The squid’s large suckers are lined with chitin teeth, enabling them to grip their adversary’s skin tightly and dig in the teeth.
© Daniel Sinoca, Thinkstock, Ocean Research & Conservation Association Inc
Food of giants
“With feeding tentacles fully extended, the giant squid can be as tall as a four-storey house”
The squid’s beak In the centre of its ring of arms is a beak, like that of a parrot. The squid uses this to chop and slice its prey.
Biggest eyes on Earth The giant squid’s huge peepers enable it to see large objects far off in the distance, which can enable a swift getaway from sperm whales on the hunt.
Scanning the ocean Sperm whales use echolocation, similar to that used by bats and dolphins, to locate their prey in the depths of the ocean.
Lungs of steel In order to reach such amazing depths and win epic battles, the whales can hold their breath for up to 90 minutes.
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MIMIC OCTOPUS The fascinating mimic octopus avoids many a danger lurking under the water with an unbelievably clever trick While other octopus species change their appearance to blend into the background, the mimic octopus is the only animal that can mimic specific animals. Even more impressively, it is the first species found to mimic more than one species of poisonous animal to avoid predators. It was only discovered in 1998, but it’s not surprising that it
stayed hidden for so long. This clever octopus changes its appearance to that of a different animal according to what is threatening it, taking on the appearance of an animal from which its attacker would flee. Scientists are still working hard to find out more about the mimic octopus, but what we know so far is almost beyond belief.
Nucleus
How they can change their colour Octopuses have pigment sacs in their skin called chromatophores. These are linked to the visual part of the brain and can be controlled by the octopus at will. Chromatophores can expand to 50 times their size, making the skin appear a lighter colour, or they can shrink to their condensed size to make the skin appear darker. This is how an octopus can change it’s colour or form patterns on its skin.
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Pigmant granules
Glial cell
Mimic octopuses
VS
REAL
Muscles at the skin’s surface turns skin texture from smooth to spiny. This helps octopuses match their background perfectly and become almost undetectable. If all else fails, the octopus can swim away and release a cloud of ink to cover its escape. Retractor muscles
LIONFISH
Erector muscles Skin
Eerector muscles contract, pulling skin into a new shape and retractor muscles relax, drawing up the skin.
MANTIS SHRIMP
Erectors then contract tightly to elongate the octopus’s skin upwards while retractors remain relaxed.
FLAT FISH
At this stage, erectors create skin texture, by expanding the shapes and areas of the individual muscles.
To flatten down again, retractors work by contracting, pulling the octopus’s skin flat once more.
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© Getty, Peters and Zabransky, Thinkstock
FAKE
How their skin muscles work
Sharks & Ocean Predators
Meet the family
Rays
These sly hunters are perfectly adapted to their habitat
Spotted eagle ray
SPOTTED EAGLE RAY Aetobatus narinari Class Chondrichthyes
The ray that can almost take off
Territory Tropical coastal waters worldwide Diet Molluscs and crustaceans Lifespan Unknown Adult weight Up to 230kg / 507lbs Conservation Status
The group of species known as eagle rays have large and elegant pectoral fins that both look and move like the wings on a bird. Found in shallow coastal seas, these fins are mostly used for swimming, but on occasion these rays have been witnessed leaping fully out of the water in spectacular aerial displays. Due to their sheer size and weight, spotted eagle rays are rarely preyed upon by all but the largest of beasts. Digging their own food of hard-shelled critters such as lobsters and oysters out of the seabed is easy for the spotted eagle, with their shovel-shaped noses and specialised teeth making it easy to extract the tasty parts from the shells.
NEAR THREATENED
Electrocytes are the electricityproducing cells that give these rays their shock – they are stacked up end-to-end in the ray’s specialised electrogenic organs, much like a row of batteries.
Cownose ray
The migratory species that gathers in groups Cownose rays are famous for their ocean migrations along the Atlantic coast and Gulf of Mexico, featuring in many glossy photographs of schools of up to 10,000 individuals swimming to and from the seasonal feeding grounds. It’s thought that these rays take temperature cues from the water and visual cues from the sun before embarking on these journeys, and when they get to their destination, there’s only one thing to do: feast. By beating their pectoral fins, they create strong currents close The cownose ray has a domed head and a rounded snout with an indentation in the centre. This gives to the seabed in a bid to uncover their prey.
COWNOSE RAY Rhinoptera bonasus Class Chondrichthyes
Territory Tropical eastern and western Atlantic Ocean Diet Oysters and crustaceans Lifespan 13-18 years Adult weight Approx 15.4kg / 34lbs Conservation Status
NEAR THREATENED
the appearance of a bi-lobed nose, much like that of their farmyard namesakes’.
Stingray
A fish with a black belt in self-defence COMMON STINGRAY Dasyatis pastinaca Class Chondrichthyes
Territory Coastal waters of temperate seas Diet Crabs, mussels, oysters Lifespan 15-25 years Adult weight Up to 350kg / 790lbs Conservation Status
DATA DEFICIENT
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Stingrays have the classic flat-bodied silhouette of the ray family, with a skeleton made of cartilage, undulating fins and a long, tapering tail. They spend their time cruising through the shallow waters of coastal seas, feeding on shelled molluscs and crustaceans, rooting around on the seabed in search of their dinner. However, this species’ trump card is its tail barb – the thing that puts the ‘sting’ into ‘stingray’. This barb is found about one third of the way down a stingray’s tail, and it can be a formidable-looking spike containing potent venom. Stingrays are generally docile creatures and so a barb attack is almost always in selfdefence – when the ray needs to fight, the tail can whip up and deliver a fatal blow.
Like their cousins the sharks, stingrays possess electrical sensors known as ampullae of Lorenzini. They can sense the natural electrical pulse of living things around them, helping to find prey.
Rays 3
1
Torpedo nobiliana Class Chondrichthyes
Atlantic torpedo ray
This species puts on a stunning performance Territory Atlantic Ocean, Mediterranean Sea Diet Small sharks, flounder, mackerel Lifespan Unknown, likely 16-20 years Adult weight 90kg / 198lbs Conservation Status
DATA DEFICIENT
This is a ray that really lives up to its superhero-style moniker. Not just your average fish, this particular member of the ray family is capable of producing strong electric currents in order to stun prey for a quick meal, or defend its honour against encroaching predators. Electric rays have two kidney-shaped organs in their bodies, situated near the gills, which are capable of producing a current of up to 220 volts. They do this by contracting the specialised muscles that are tightly packed together within these electrogenic organs. Because of this formidable party trick, electric rays are able to swiftly stun and then feast upon dinner delights that would ordinarily be too fast for them to catch. OCELLATE RIVER RAY
It’s easy to see why this fish is also known as the ‘peacock-eye’ ray – like the eyed feather of a peacock, the detailed pattern on its back can act as a decoy for would-be predators.
Potamotrygon motoro Class Chondrichthyes
Ocellate river ray
The freshwater addition to the family
Territory Southern South America Diet Small molluscs, crustaceans and insect larvae Lifespan Unknown Adult weight Up to 32kg / 74lbs Conservation Status
DATA DEFICIENT
Where most of the ray family are ocean-dwelling critters, there are a few select members that make their home in the fresh water of river basins. The ocellate river ray is one of these, living in the riverine systems of South America. Looking like a flat, circular pancake with a long spined tail and prominent eyes, this ray lies at the bottom of sand banks and silty river bottoms in wait for tasty prey to come along. When lying on a sandy riverbed, their gills and mouths on the underside of the body can’t be used, so the ray (like many other ray species) takes in water to pass over the gills through a special opening known as a spiracle, situated behind each eye.
MANTA RAY Manta birostris Class Chondrichthyes
Territory Tropical seas worldwide Diet Plankton Lifespan Unknown, thought to be 50–100 years Adult weight Up to 1,350kg / 2,976lbs Conservation Status
VULNERABLE
Manta ray
These gentle giants are the largest rays of them all The colossal manta ray is one of the ocean’s biggest softies. Its huge size might look daunting with its huge fins that could comfortably cover your family car, but these creatures are of no threat to humans whatsoever. Manta rays feed by opening their large mouths and drawing in seawater. They filter all of the tiny microorganisms out of each liquid mouthful – one full-grown manta can suck down 27kg/60lbs of food in one day! There are two species of manta ray. One is proportionately smaller and lives on tropical reefs. The other is more migratory and travels from one area of oceanic upwelling to another in search of plankton.
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2 1. Most intelligent Manta ray
3. Rarest Maltese ray
Manta rays have the largest brain size relative to body mass of all fish species and often exhibit cooperative and coordinated feeding behaviour. Manta rays are much more than just pretty faces.
2. Smallest Lesser electric ray This tiny little critter can be found in shallow waters on the east coast of USA and South America and in the Gulf of Mexico. It is on average just 20cm/8” across and weighs about 0.5kg/1lb.
Listed as Critically Endangered by the IUCN Red List, the Maltese ray was once common in the Mediterranean Sea. It is now restricted to the Sicilian channel around Malta, and is blighted by heavy trawling.
4. Most spectacular Mobula ray Mobula rays gather in huge shoals at certain times of the year. To stand out from the crowd, they launch themselves into the air and land on the water with a resounding boom noise.
The manta is sometimes known as ‘devil ray’, due to the two large fins on its head that look like horns. These are actually used to guide plankton-rich water into the mouth while feeding.
A butterfly ray is not an insect Butterfly rays are not at all related to real butterflies! Instead, this group of rays get their name from their wide set of pectoral fins that look very much like wings, along with their short sharp tails that resemble a butterfly’s body. The rays use their strong fins to ‘fly’ through the water, mimicking a slowmo version of a wing flutter.
© © Thinkstock; Thinkstock; Dreamstime FLPA
ATLANTIC TORPEDO RAY
The majestic wing-like fins are characteristic of eagle rays as a group, but the spotted eagle ray is even more distinctive with its beautiful colouration and polka-dot pattern.
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BOTTLENOSE DOLPHIN Tursiops truncatus Class Mammalia
Territory Global Diet Fish and squid Lifespan 50 years Adult weight 500kg (1100lb) Conservation status
LEAST CONCERN
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Dolphins
SMARTEST ANIMALS ON EARTH Famous for their ability to learn and mimic human behaviour, the real story behind the immense intelligence of dolphins lies in their astounding wild behaviour Whales and dolphins have fascinated human beings for millennia, with dolphins featuring in cave paintings dating back almost 3,000 years. The first descriptions of dolphins came from sailors, who spoke of enormous creatures with large eyes, long beaks and sharp teeth. Artistic depictions of them at the time looked more like sea monsters, admiring their strength and cunning hunting techniques. Over the years, humans
soon discovered that dolphins were intelligent mammals of the sea and began to study them. As technology developed that could record their underwater calls, scientists began to realise how complex their behaviour and communication truly was. Exactly what dolphins are speaking about is still unclear, but as research progresses we are learning more and more about the most intelligent animals in the ocean.
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Communication
Dolphins stay in contact at all times, constantly chirping and clicking to one another about sources of food, group life and the threat from predators Living under water means that dolphin communication works extremely differently from animals that live on land. Sound is the basis of almost all dolphin interactions and the exact information different noises contain is still a mystery to marine biologists. Staying in contact is crucial for dolphin survival and their social intelligence has developed over thousands of years of evolution. Each dolphin makes a unique whistle sound that acts as a name tag. Dolphins introduce themselves to others around them and
recognise one another by these signature sounds. Closely bonded dolphins even mimic one another’s whistles, which is like calling out for a friend by name. The dominant form of communication in primates is through sound, but the primary sense of apes and monkeys is visual. Scientists now think that dolphin communication is more efficient than our own, because they can replicate any sound that they hear. These animals build up mental pictures of the environment using biological sonar and
Social networking Dolphin groups have a very fluid social structure, with smaller groups constantly combining and splitting up again. This means that they can meet hundreds of others on a daily basis. This has been likened to social networking, with dolphins maintaining lots of weak bonds with others they have met briefly in the past. The networks that build up help transfer information over long distances and work just like Facebook. News is transferred through friends of friends and means that dolphins can stay in touch.
How dolphins speak to one another All the sounds a dolphin makes come from the blowhole. By forcing air out between the powerful muscles that keep the blowhole sealed under water, they can create an enormous variety of unique sounds, from simple clicks to complex whistles and buzzes.
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Clicks Dolphins emit very short, high-pitched snaps of sound at regular intervals
Buzzes Associated with surges of emotion, dolphins create buzzes when excited or angry Whistles These flowing sounds are individual name tags to help dolphins recognise one another
they might be able to project these pictures to others, like a hologram. This surpasses the amount of information humans can convey with speech and dolphin conversations could be up to 20-times more detailed than that of apes and other primates. Not all dolphin communication is based on sound, though, after arriving and before leaving a group they touch each other. Even altering their posture while swimming is a form of communication and a dolphin can invite others to play by wriggling its body.
Dolphins Proving self-awareness
Bottlenose dolphins have been seen to recognise themselves in the mirror!
Dr Diana Reiss is a world-renowned dolphin expert. She led the team that proved dolphins can recognise themselves in a mirror “At my lab in 2001 I did a study with a very simple design. You’re asking if a dolphin understands that what they see in the mirror is an external representation of themselves. We exposed dolphins to a mirror and we gave them time to learn about how mirrors work. We saw three basic stages the animals went through to show that they could recognise themselves. The first stage we call social behaviour. The animals try to touch the mirror, look around behind it as if there’s another dolphin there. When seeing their reflection they reacted as if they were seeing another of their own kind. Most animals never get past this stage. “The second stage we saw emerging was more than just testing the mirror. The animals seemed to be testing what was happening in the mirror image when they did certain things. That is when the light bulb went on. That’s when they knew that they were seeing themselves in the mirror. “In the third stage, the animals shied to self-directed behaviour. They examined themselves in the mirror, looking at parts of their body that were otherwise not visible. They looked at their eyes, inside their mouths and made unusual movements in front of the mirror. They were using the mirror as a tool to view themselves. “We went on to do what’s called a mark test. We put the mirror into the water for 30 minutes every few days and watched the behaviour of the dolphins. We then called them over and marked their bodies in different places with a non-toxic marker. They immediately raced to the mirror to examine the marked area.”
Just like us As humans, we tend to underestimate other animals, believing our behaviour is unique to us. But dolphins share a few of our traits, showing some extreme intelligence
Dolphins can eavesdrop
Dolphins can deceive each other
Dolphins have communication abilities that were once thought to be unique to humans. Their ability to eavesdrop gives us a clue as to how clever dolphins are. Not only can they listen in to other conversations, but they can also divide their attention between their own vocalisations and other sounds at the same time. This maximises the information they are taking in.
The ability to follow another animal’s gaze shows immense intelligence and human children begin to develop this skill after the first year of life. Dolphins use this skill to tell what others are looking at without needing to communicate about it. Dolphins can draw another’s attention to an object by pointing at it. In fact, these mammals can even deceive one another by directing it elsewhere.
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Emotional intelligence Feelings of happiness, love and heartbreak are human concepts but these animals share our ability to feel emotion These animals form extremely close bonds with their families and experience emotions that humans might call love. Newborn dolphins rely on their mothers and older siblings for survival and calves stay with their family for around six years. When a relative dies, dolphins experience grief and mother dolphins carry their lost calves around with them for extended periods of time. Young that have lost their mother are known to visit their mother’s favourite locations after her death. When a dolphin group spies a dolphin carcass they approach it and even take it in turns to surface for a breath of air so the corpse isn’t left unattended. Dolphins are famous for their tendency to help animals of other species. There are reports of dolphins helping exhausted seals back to shore and even leading beached whales back to the safety of deep water. In 2008, a bottlenose dolphin arrived at the scene of a stranded mothercalf pair of pygmy sperm whales on a beach in New Zealand. The dolphin, known by locals as Moko, led the pair of whales from the shallows directly into deeper water. The only explanation of this behaviour is that dolphins are capable of experiencing empathy.
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EQ level
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What is EQ? Encephalisation quotient is a comparison of the size of an animal’s brain and its overall body size – dolphins have an extremely high score
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Dolphins
Problem-solving Life presents animals with puzzles on a daily basis and only animals with the best brains can find their way around the trickiest problems
01 Tool use
02 Hunting
03 Avoiding predators
Dolphins around the coast of Australia have started to use tools to protect their sensitive beaks. The fish that burrow under the sand don’t have an air-filled swim bladder, making them difficult to locate with sonar. To combat this, the dolphins began foraging while shielding their faces with sponges.
Across the globe, different groups of dolphins have perfected a variety of strategies to catch fish. In Brazil, a pod of dolphins has teamed up with the local fishermen. They herd fish toward the shore and give the fishermen a signal to cast their nets. The dolphins then get their reward of leftover fish.
Dolphins form a defensive circle around weak members of their pod when a predator approaches. Sharks and other carnivorous fish would gladly attack a lone dolphin, but rarely approach large groups. Even the colouration of some dolphins confuses predators, helping them keep camouflaged.
How dolphins hunt Creativity shows how intelligence and brainy dolphins have invented unique ways to catch fish
Herding fish Deep-water dolphins herd fish into a ball and take turns to swim through the middle. They stay in constant contact and swim at top speed to keep the fish where they want them.
Confusing the prey
Makeshift nets
One dolphin swims in a circle while beating its tail against the silt. This creates a ring of mud that confuses the fish inside.
The rest of the group wait for fish to leap out of the makeshift net.
Blowing bubbles The dolphins surrounding the fish create nets of bubbles.
Going on land! Risking their lives to catch fish, dolphins chase fish to the banks of rivers and seashores. The animals launch themselves out of the water to snatch the escaping fish.
The art of hydroplaning Speeding through shallow water allows dolphins to access fish that swim close to the shore. This is called hydroplaning and the dolphin skims along in the shallow surf at high speed.
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How dolphins think Their complex brain fuels the animal to process information, store memories and solve puzzles The emotional centre of a dolphin’s brain is more complex than in a human brain. It has a larger surface area and more folds, which indicates that their brains have evolved to process emotion. Whale and dolphin brains also contain specialised nerve cells called spindle neurons. These cells are associated with the ability to reason, experience emotions and make quick decisions. These were once thought to be possessed only by humans and were even nicknamed ‘the cells that make us human’. What’s more, dolphins have three-times as many of these cells as humans do, even when accounting for their larger brain size. Not only do dolphins and their relatives have these spindle cells, but they have also had them for twice as long as humans.
Along with this amazing brainpower, dolphins have one of the longest memories of the entire animal kingdom. Even if dolphins are separated for 20 years, they are still able to remember a familiar face. This was noted in aquaria in the United States, when dolphins that had been briefly housed together at the age of only six months old were played audio of one another’s signature whistles. Upon hearing the familiar call they instantly responded, whereas an unfamiliar call is often ignored. Dolphins also have good short term memory and can remember lists of items. Some dolphins are even able to understand sentences of human speech. Dolphins in a 1993 study could remember strings of up to five words and responded to what the human was asking for.
“Dolphins in a 1993 study could remember string of up to five words and responded to what the human was asking for”
Dolphin and human brains compared Dolphin brains are larger than human brains, but have the exact same areas and components. The wrinkled surface of the brain is called the cortex and in whales and dolphins this layer has more folds than in humans. This points to extreme intelligence and the dolphin brain has evolved perfectly to help them survive the seas. RIGHT The muscular dolphin is capable of some truly incredible acrobatics in and out of the water
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Dolphins
“Dolphins have one of the longest memories of the entire animal kingdom”
ABOVE It’s no wonder that dolphins are such a popular animal – their cheeky grin is very infectious
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Spotters’ guide
Bottlenose dolphins See nature’s greatest acrobats in their natural habitat in almost any ocean around the world
Bottlenose dolphins can be found in almost every ocean. They generally live in coastal waters and can even be spotted from beaches. Bottlenose dolphins can be seen at all times of the year, but tend to be most abundant in the warmer months when they give birth to calves. From Scotland’s Moray Firth to the tip of South Africa, these animals are distributed worldwide. They can be seen from land regularly, but spotters may want to take a specific tour to see them up close. Those taking a dolphin-watching cruise should wrap up warm because it gets extremely cold out on the water. Taking a camera is always a good idea to capture playful dolphins in mid-air. Dolphins are also known for riding in the waves a boat creates. This is called
bow-riding and leaping through the freshly churned water is a dolphin’s equivalent of surfing. Taking a boat trip through a well-known dolphin area is likely to attract some animals, although it’s often best to leave the boat operation to the experts. Notoriously playful and curious, bottlenose dolphins are known to approach swimmers. Those looking for an up-close experience can swim, snorkel or even SCUBA dive in dolphin territory. But remember they are still wild animals, and are still equipped with a row of sharp teeth and a muscular body. It’s always best to do a trip like this with an experienced company to make sure swimmers are safe at all times. Wild dolphins should not be approached or pursued, but are quite likely to inspect people in the water.
BOTTLENOSE DOLPHIN Tursiops truncatus Class Mammalia
Territory Tropical and temperate waters Diet Fish Lifespan Up to 50 years Adult weight 500kg (1100lb) Conservation Status
LEAST CONCERN
5 places around the world to see dolphins AK Wildlife Cruises, UK
www.akwildlifecruises.co.uk Operating all year round, this company spots dolphins, whales and seals on a regular basis. Newport Landing Whale Watching, USA
www.newportwhales.com Operating from Long Beach California, spotters can take tours by boat or by plane. Dolphin Watch Cruises, Australia
www.dolphinwatch.com.au Leaving from Jervis Bay in southern Australia, these 90 minute trips provide cover from the sun. Dolphin Swims, Egypt
www.dolphinswims.co.uk This company take snorkellers out to dolphin areas for the chance to swim with the wild animals. Advantage Tours, South Africa
www.advantagetours.co.za See dolphins and humpback whales off the western coast of South Africa, or even take a hippo tour. Bottlenose dolphin range
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Bottlenose dolphins Expert advice, the best chance to see a bottlenose Cornwall-based AK Wildlife Cruises Captain Keith Leeves takes spotters out to see dolphins all year round. Are there any telltale signs that dolphins are in the water? We always look for birds, they are a great indicator of dolphin presence. Fast travelling dolphins will make a lot of white water and splash around, so look out for disturbances in the water. On a calm sunny day, look out for a glint of light bouncing off an animal’s smooth wet skin. How much can spotters interact with dolphins? Quite a lot, depending on the animals. They are playful and inquisitive and if they come toward your boat then that’s the animals choosing to interact with you. There have been studies indicating that high pitched voices excite dolphins and may even attract them. Should spotters feed wild dolphins? No. There is always a risk that dolphins could become dependent on being fed by humans. It’s not like putting a bird feeder out in your garden, big marine mammals shouldn’t be fed. It would be lovely to be able to feed these animals, but we really can’t condone it. What advice can you give to readers who want to see dolphins where they live? If you can find a dedicated operator, go out with them. Not only for their
knowledge of the animal but also the vast experience behind the operators can really help. One can never guarantee a wildlife sighting. What should dolphin spotters wear? Even in hot places and during the summer it can be much cooler offshore. Always take plenty of layers, waterproofs, hats and gloves. Take good pair of binoculars or a camera and in the summer take plenty of sun cream. In the sun you do get a lot of glare and polarised sunglasses will help you see animals through the water. Can you describe what an average bottlenose dolphin sighting is like? They love nothing more than showing off and playing and oen do incredibly high jumps. They might keep their distance and we never infringe on that. There are occasions when they will come rushing over to say hello and bottlenose dolphins in particular are extremely playful. What are the best dolphin-spotting weather conditions? Flat, calm sea is just perfect so you can see their fins. If there’s anything going on you can’t miss it. Sunshine isn’t always the best because of glare. An overcast day is an excellent day to go out, oen providing the best sighting conditions.
Bottlenose dolphins generally swim in groups of ten to 25
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Atlantic blue marlin One of the fastest fish in the ocean, this ferocious fish is armed with a dagger to warn away predators and intimidate inferiors Named after its preference for deep, open ocean, the Alantic blue marlin can be found at depths of over 400 metres (1,300 feet), though typically it doesn’t stray below 200 metres (650 feet). The only predators a marlin has to fear are large oceanic sharks like the tiger shark, and the humans that seek to hook it. Menacing hooks attached to floats snake behind fishing vessels, even through the night when the marlin spends most of its time at the surface. They are attracted to the bait and get caught, even if they aren’t the fishery’s target species. It’s a tough life being a large fish, but thankfully the marlin has a notso-secret weapon. The long, pointed rostrum or beak helps the fish secure
a meal. Research shows that these marlins eat over 45 different prey species, and around 40 per-cent of prey sustain injuries from the sharp spear. More than 80 per-cent of those received slashing injuries and almost 10 per-cent were sliced in two. Marlins tend to spear prey and then shake their head violently before engulfing their meal, especially when hunting fast-swimming shoaling fish. Slow-moving, solitary prey doesn’t usually require impaling, and is simply attacked out of the blue.
ALTANTIC BLUE MARLIN Makaira nigricans Class Actinopterygii
Territory The Atlantic ocean Diet Bony fish and squid Lifespan 15 years Adult weight Up to 818 kg (1,803 lb) Conservation Status
3 things you need to know about marlins
VULNERABLE
Stripes Billfishes, like the blue marlin, have the ability to rapidly change the colour of the stripes along their sides. This could be to startle predators or be invisible to prey.
Females are up to four times as large as males, and all trophy catches are females A blue marlin can travel 5,556 kilometres (3,000 nautical miles) in a mere 90 days
© Thinkstock
Marlins have an organ that keeps its eyes and brain warm to help it see and think as clearly as possible
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Atlantic blue marlin Low odds Only around one per-cent of marlin eggs make it to adulthood, with the rest being eaten by plankton feeders.
Spine Marlins have 24 vertebrae in the spine, which help them reach swimming speeds of up to 97 kilometres (60 miles) per hour.
Bill The sharp bill is essentially the marlin’s fishing rod. It uses it to spear fast-moving fish, up to 75 per-cent of which is skipjack tuna
Eyes Marlin vision is excellent, and research even suggests they can detect limited colour. Their lenses block out ultraviolet light, making them blind to their own UV shimmer.
Microscopic to monstrous It’s difficult to believe the enormous blue marlin begins life as a tiny speck, floating helplessly through the ocean Altantic marlins are known as ‘broadcast spawners’. This means that a female releases several million unfertilised eggs into the water column while a male injects the water with sperm. The one-millimetre (0.04-inch) eggs are fertilised in the open water and take around a week to hatch. It then takes up to four years for the fish to reach maturity, all the while looking very different from its adult form. Pectoral Fins The best way to tell the difference between a marlin and a swordfish is to look at the pectoral fins. Marlin fins are small, but swordfish fins extend far below the body.
Marlin egg Marlin eggs float free as plankton, and their sheer numbers ensure at least a few survive to adulthood.
Adolescent marlin Though still measuring only 22 millimetres (0.9 inches), the fish is recogniseable as a marlin.
© FLPA
“Marlins tend to spear their prey and then shake their head violently before engulfing their meal”
Marlin fry Only 12 millimetres (half an inch) long, this tiny larva grows to reach up to four metres (14 feet).
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Saltwater crocodiles
All About
Saltwater crocodiles The sea’s most unexpected predator, discover how the most aggressive crocodile became such a lethally effective predator
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Anatomy of the world’s largest reptile Saltwater crocodiles are extremely successful predators thanks to their bony armour, powerful muscularity and an incredible bite force that enables them to overwhelm even large prey
SALTWATER CROCODILE Crocodylus porosus Class Reptilia
Territory Indo-Pacific coasts Diet Carnivore Lifespan 70-100 years Adult weight 400-1,000kg / 880-2,200lbs Conservation status
Hard palate A flap at the back of the hard palate enables Trachea the crocodile to open The crocodile’s its mouth underwater without drowning, by windpipe is supported by rigid rings of stopping water getting cartilage, preventing to the nose and lungs. it from being crushed as they swallow large mouthfuls of meat.
Snout
LEAST CONCERN
Nictitating membrane Crocodiles have translucent third eyelids, which move horizontally across the eyeball, protecting their eyes underwater while still enabling them to see.
Nostrils The nostrils and eye sockets are positioned on the top of the skull, enabling the crocodile to breathe and see even when partially submerged in the water.
Eye socket
Horny scales Square, flat scales on the underside of the crocodile enable it to move smoothly across the ground. This provides the tail with a large surface area for swimming and lunging at prey.
Mandible
Scale disposition Transversal rows
Longitudinal rows
Collar scales
Short limbs Interlocking teeth
Collar
Ventral scales without holes
Saltwater crocodiles have short limbs and when on land tend to crawl on their bellies.
Bottom scales of the tail
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Lateral scales of the tail
JUVENILE
INFANCY Determining gender Pre-hatching The sex of a newly hatched crocodile is determined by the temperature of the nest.
Heart The crocodile has a second aorta, enabling it to divert acidic Webbed deoxygenated blood Lungs feet to the stomach and Crocodiles use their helping to produce lungs as a buoyancy more stomach acid. aid and swallow stones for ballast. This helps them to manoeuvre easier when underwater.
Hatching 0 Days When crocodiles hatch, they cry to attract the attention of their mother, who digs up her young and carries them to the water.
Learning to swim 0-8 months Young crocodiles stay close to one another for two to eight months, until they grow larger.
Separation 8 months As the young grow they begin to move farther away, but most remain within five kilometres (3.1 miles) of the nest site.
MATURITY Competition for space 1-10 years Smaller crocs can’t compete for the best territory, so are vulnerable to stronger rivals.
Sexual maturity – females 12-14 years Once they reach maturity, females will lay an average of 40 to 60 eggs every year.
Closest family
Bite force
Closely related to the saltwater crocodile are…
Nile crocodile The Nile crocodile is the second largest reptile in the world, measuring up to six metres (20 feet) in length. These creatures are apex predators and capable of attacking prey as large as young hippo.
Mugger crocodile Found in the Indian subcontinent, the mugger is a heavily armoured crocodile. Despite measuring up to four metres (13 feet), muggers prefer smaller prey to the saltwater, feeding on fish, turtles and birds. Liver
The saltwater has the highest bite force of any crocodile, with up 2,410 megapascals (350,000 pounds per square inch).
American alligator Crocodiles have a V-shaped snout and when their mouths are closed, both rows of teeth are visible. Alligators have shorter U-shaped snouts with a huge bite force and their upper jaw hides the lower teeth. Pancreas
Dermal pressure receptors Sensory pits in the scales on a crocodile’s head enable it to detect slight changes in water pressure. This means the creature can even hunt in murky water.
Lingual salt glands Reptilian kidneys are less efficient than mammalian ones, so crocodiles rely on glands to pump salt from their blood.
Kidney
The tail is used to move swiftly in the water.
Tail
Stomach
Posture
The stomach of a saltwater crocodile is ten-times more acidic than a human’s, enabling it to digest bone and hooves.
The posture is semierect, with knees and elbows slightly bent.
Double caudal crest Intestine Simple caudal crest
How the saltwater crocodile gallops This huge lizard is capable of galloping, but only when threatened. Over short distances it can reach speeds of up to 15 kilometres (nine miles) per hour.
Sexual maturity – males 16 years Male crocodiles mature later and spend most of their adult lives competing for territory, optimal basking locations and of course female crocodiles.
Reproduction 16+ years Saltwater crocodiles reproduce once a year during the wet season. The female guards the eggs and then the hatchlings.
Apex predator 20+ years Older crocodiles reach average lengths of five metres (16.4 feet) and are capable of taking down almost any animal in their path.
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Honed senses and killer instincts The saltwater is the largest and most aggressive of all the crocodile species, using its natural abilities and honed senses to survive Crocodiles do most of their hunting in the evening and at night. They are primarily sit-and-wait ambush predators, so spend their time partially submerged in the water, with barely more than their eyes and nostrils poking out of the surface. They are agile swimmers and can dive for long periods of time without even surfacing to breathe. They are also able to slow their heart rate to just two or three beats per minute. When in the water, they use their lungs as a buoyancy aid and are also known to eat stones, which act as a ballast, helping to stabilise their large bodies below the surface. Saltwater crocodiles also pack a combination of sharp senses to stalk their prey. They have keen eyesight and the backs of their eyes are covered in guanine crystals that reflect the light, enabling them to see more effectively in the dark. Sensory pits on their heads also enable them to feel changes in the vibrations within the water. Smaller crocodiles feed mainly on crustaceans, insects and mammals, but their diet varies depending on the location. Saltwater crocodiles use their teeth for impaling and securing their prey, but they are ineffective when it comes to chewing. Instead, they swallow their prey whole, relying on extremely acidic stomachs to dissolve tough tissues such as bone and horn. For larger prey, the crocodile thrashes its muscular body, swinging its head to
tear the animal into more-manageable chunks, which can then be swallowed swiftly. The aggressive thrashing, lunging and fighting displayed by the saltwater crocodile is fuelled by anaerobic respiration. This rapid method of generating energy without oxygen enables them to ambush their prey at high speed, using their tails to propel themselves out of the water and tackling their target to the ground before dragging it under. However, it results in the build up of lactic acid in the blood, lowering the pH and building up an oxygen debt. In order to repay this debt, the crocodile needs to rest after periods of intense activity and can only fight or hunt in very short bursts. A crocodile can survive for extended periods of time without feeding, so the majority of its life is sedentary. Like other reptiles, they are cold-blooded and don’t generate enough body heat to maintain a constant temperature, instead relying on their environment to heat and cool their bodies. During the day, saltwater crocodiles spend most of the time basking in the Sun. The bony scutes that make up the armour plating on their backs are covered in tiny blood vessels and act like miniature solar panels, absorbing heat and warming their bodies. If they become too warm, they open their mouths, seek shade or enter the water to cool themselves down.
Saltwater crocodile diet HATCHLING All teeth but no bite Despite having a full set of teeth, newly hatched saltwater crocodiles are small, measuring under 30 centimetres (12 inches) in length. They cannot really tackle prey any larger than insects or very small crustaceans and fish.
JUVENILE Triple the size, triple the threat Aer a year, the crocodiles have more than tripled in length and are capable of hunting a much wider variety of prey. They catch fish underwater, lunge at small mammals on land and leap into the air to capture birds.
ABOVE A saltwater crocodile lying at the shore of a swamp, basking in the rays of the Sun
RIGHT With the nostrils and eye sockets positioned on the top of its skull, a crocodile is able to stalk its prey while nearly totally submerged
Crocodiles are capable of sudden bursts of energy to surprise their prey, but only for short periods
ADULT A ravenous adult Mature saltwater crocodiles are apex predators and their diet is restricted only by their size. Most of the time adult crocodiles eat smaller animals, including crabs, sea turtles, birds, and wild boar. However, seven-metre (23foot) adult males can bring down prey as large as a water buffalo.
Crocodiles are agile swimmers and can spend up to an hour submerged underwater
“A crocodile can survive for extended periods of time without feeding”
Saltwater crocodiles
The powerful reach for prey
2-3 metres
Saltwater crocodiles are well known for their high-speed lunge from the water to the shore, but they can also perform this rapid strike in the air. Their tails are incredibly muscular and they can generate enough power to propel themselves vertically out of the water. This technique is most often used by juveniles to hunt insects, but adult saltwater crocodiles are known to jump to catch birds and even pull animals from overhanging branches. Some lighter crocodiles can clear the surface entirely, becoming airborne as they catch their prey.
Leaping at speed Saltwater crocodiles can leap two to three metres out of the water at incredible speeds of around ten metres per second (around 22 miles per hour).
Perfectly formed scales The scales on the underside of a crocodile’s abdomen are regularly shaped and arranged in a uniform pattern to minimise friction.
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How a predator takes down its prey
Discover how a saltwater crocodile can take down prey of all shapes and sizes
Lurking silently beneath the surface of the brackish, cloudy water, the saltwater crocodile is the ultimate opportunist predator. The mottled green and brown of its much-prized hide provides the perfect camouflage, concealing it from any animal unfortunate enough to take a drink from a nearby bank. As an eater with a wide diet, a saltie will devour pretty much anything it can sink its well-suited, peg-like teeth into. If it’s small enough, animals such as monkeys and birds will be swallowed whole, while larger prey such as wild boars and water buffalo will be dragged under the water and drowned.
01 Strike It strikes from the water, launching forward using its muscular tail for propulsion.
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The prey Water buffalo are a common prey for saltwater crocodiles, who usually stalk and ambush them from the shallows.
02 Neck bite Vice-like grip With its pointed teeth and bone-crushing bite force, once a saltwater takes hold, its prey rarely escapes.
The crocodile grabs its prey by the neck, crushing the trachea with a bite force stronger than any other animal on the planet.
Saltwater crocodiles
04 Drowning 03 Death roll Using its immense body weight to roll sideways, it generates enough force to disable a large animal and also to tear it into bite-sized pieces.
Breathing The hard palate of a saltwater extends all the way to the back of the mouth, so the airway isn’t squashed as it struggles.
Many animals are killed by the bite alone, but crocodiles will also repeat the death roll manoeuvre in an attempt to drown their prey.
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The courtship of a fearsome beast Despite their fearsome reputation, saltwater crocodiles have a surprisingly gentle courtship ritual and the females are nurturing mothers that guard their young fiercely
BELOW When male and female crocs court, they oen stay near each other, swimming side by side
Just like for many other creatures in the world, the mating season is a tense time for saltwater crocs
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Saltwater crocodiles mate during the wet season, with the males competing loudly for females. In a bid to demonstrate their eligibility, they open their mouths, expand their chests and emit infrasonic and audible sounds that shake the nearby water. This often escalates to fighting, with violent tail-whipping and biting. Once a male has secured his territory, he’s free to attempt to mate with any female he can find. If the female is receptive to mating, she will raise her head to signal submission and the courtship ritual can begin. Male saltwater crocodiles are among the most aggressive animals on the planet, but when pursuing a female they employ gentler tactics. They have scent glands on their chins and rub their heads against the female’s snout to cover her in pheromones. Partners also swim together, with the male dipping below the female to blow bubbles on her and performing infrasonic water dances, vibrating his flanks to create a lowpitched sound in the water. However, even if a male is successful in courting a female, another male may attack the pair during mating and the fighting often continues in the water. During the wet season, saltwater crocodiles move inland to freshwater swamps and marshes,
preferring to lay their eggs in nests constructed from vegetation, in sheltered locations away from the tidal waters of estuaries. The eggs take between 65 and 114 days to hatch while the female defends the nest. She waits in nearby water channels and is efficient at warding off would-be predators, but the biggest threat to the nest is flooding, with around 70 per cent of eggs drowning. The nest not only provides protection from predators and prevents the eggs from drying out, it also plays a vital role in determining the gender of the hatchlings. The surrounding temperature often dictates the sex of a newborn reptile, so instead of having the classical X and Y chromosomes, whether or not a crocodile hatchling is male or female is defined by how hot or cold the nest is. Eggs will only develop into male hatchlings if the temperature is very near to 31.6 degrees Celsius (88.9 degrees Fahrenheit) – more than a degree or two above or below this temperature will produce only females. The first few years of a saltwater crocodile’s life are incredibly dangerous and the hatchlings are vulnerable to attack by predators of many different varieties. The female remains with her offspring for the first few months, as they huddle together in crèches, calling to one another to stay together. Within a year they begin to venture further away, but larger male crocodiles pose a significant threat and very few hatchlings make it to adulthood. Those that survive go on to become almost invulnerable to any predator, other than humans.
“The first few years of a saltwater crocodile’s life are incredibly dangerous and the hatchlings are vulnerable to attack by predators”
Saltwater crocodiles
A crocodile nest Saltwater crocodiles are mound-nesters, building a protective shell of mud and vegetation to keep their developing eggs warm and safe Egg tooth
Guarding the nest
The tough skin found on the end of a baby crocodile’s snout enables it to break through the egg’s inner membrane.
The female crocodile is an attentive mother and guards her nest against predators, waiting in nearby water channels in case any animals attempt to approach. When the eggs begin to hatch, the female digs the nest open and sometimes even carries the hatchlings to the water in her mouth. Her guard duties continue until the hatchlings are several months old.
Egg shell Saltwater eggs are oval and measure about eight centimetres (3.1 inches) in length, about the size of a goose egg.
Hatchling Newly hatched crocodiles cry, attracting the attention of their mother. She responds by opening the nest, helping the hatchlings out of their eggs and into the water.
Nesting Crocodile eggs are vulnerable to changes in temperature and predation. Females bury them in the nest to hide them from view and keep a constant temperature.
First weeks of life Before baby saltwater crocodiles hatch, they take in the remainder of the egg yolk to sustain themselves until they are able to feed. The hatchlings themselves are large, measuring around 30 centimetres (one foot) from snout to tail and already have a powerful bite. The hatchlings make repeated vocalisations and use these noises to remain close together, guarded by the adult females. Even at this young age, they’re aggressive and quickly establish a hierarchy
Egg tooth lost The egg teeth that enable the hatchlings to emerge from their eggs are no longer needed and quickly disappear.
Camouflage The dappled-brown colouring of the scales on the back of the hatchlings help to keep them hidden from predators.
Safe transport Saltwater mothers will often carry their hatchlings to the water inside their open mouths.
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Home of a killer reptile Where the saltwater crocodile calls home The saltwater crocodile was once widespread across south-east Asia, but now is restricted to the shorelines, from the east coast of India, across south-east Asia, down into the Northern Territory of Australia and its islands. Despite their name, saltwater crocodiles don’t live in the sea and instead inhabit brackish water – where freshwater meets saltwater. The crocodiles spend most of their time in tropical estuaries, rivers and swamps, but vary their exact location according to the seasons. When it’s dry, they congregate in tidal rivers, estuaries and mangrove swamps. During the wet season they move up to 150 kilometres (90 miles) inland to freshwater swamps, billabongs and river channels to build their nests. Saltwater crocodiles can venture into the open ocean and by using a combination of floating, riding currents and swimming, are capable of travelling thousands of metres. Unlike most other crocodiles, they have special glands in their mouths, enabling them to get rid of excess salt when living away from freshwater. Some spend so long at sea that they have been spotted with barnacles
attached to their scales. Their remarkable ability to travel long distances at sea has enabled the species to populate remote locations such as the Solomon Islands. The saltwater crocodile is listed as being of Least Concern on the IUCN Red List and faces relatively few environmental threats. However, one of the major causes of saltwater crocodile mortality in Australia is accidental capture in fishing nets. Feral water buffalo also pose a threat to the saltwater crocodile population. Originally introduced into Australia during the 19th century, the animal causes significant environmental damage, with herds trampling the wetlands. They destroy vegetation and increase drainage, destroying the saltwater crocodile’s habitat. Nevertheless, the saltwater population in northern Australia is doing so well that the government has to go to great lengths to keep the crocodiles away from built-up areas, capturing and re-releasing the creatures to move them away from towns. Controlled hunting has even been suggested to keep the population at a manageable level.
Environmental threats In many areas saltwater crocodiles are thriving, but they do face some problems in their environment Problem crocodiles When crocodiles become a danger, they are relocated to crocodile farms to be used as breeding animals. However, illegal culling also occurs in some areas. Agriculture Outside of Australia, some freshwater habitats are suffering due to agriculture. Swampy grounds are rich and fertile, so some are being turned over to growing crops. Fishing One of the major causes of crocodile mortality in Australia is fishing nets accidentally catching the creatures. Measures are in place to protect the animals from the fishing industry.
Using the environment These cold-blooded predators use the water to regulate their body temperature, as well as to stalk and ambush prey.
Nearest neighbours Take a look at some of the animals sharing their environment with this aggressive predator
Flat-back sea turtle In northern Australia, crocodiles share their estuaries with flat-back sea turtles. Although they measure about a metre (3.3 feet) in length, the turtles have a so shell and can be vulnerable to crocodile attacks.
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Domestic water buffalo Water buffalo are farmed for meat, milk, skin, bone and horn. They are also used to plough paddy fields, as well as pack animals to move heavy loads. They are one of the largest animals preyed on by crocodiles.
Spectacled flying fox These rainforest-dwelling fruit bats can weigh up to a kilogram (2.2 pounds). Saltwater crocodiles have been observed stalking colonies of flying fox and will occasionally snatch them from the air.
Green tree python These non-venomous snakes spend most of their time in trees, feeding on small mammals. They adopt a characteristic position when resting, looping their bodies over the branches and resting their head in the middle.
ABOVE A high-angle view of Ontong Java, north of the Solomon Islands
Saltwater crocodiles
Saltwater crocodiles and humans Saltwater crocodile skin is extremely valuable, so the population was badly dented between 1940 and 1970 due to poaching. In the 1970s the Australian government brought in laws to protect the crocodile and the species is now doing well. Saltwater crocodiles are extremely dangerous to humans and have a reputation for attacking people and even boats. Smaller crocodiles attack humans as part of a territorial display, but larger individuals can attack to kill. Most saltwater crocodiles live in remote areas, so the opportunity to prey on humans is rare, but the slightly smaller Nile crocodile lives close to humanity in several areas and is responsible for hundreds of deaths each year in Africa, demonstrating the potential that these reptiles have as human-killers. In remoter, moreimpoverished and isolated parts within saltwater crocodile range, it’s likely that several attacks go unreported each year. As part of the conservation effort in Australia, problematic and dangerous individuals are not always culled, but instead relocated to crocodile farms to be used as breeding animals. These farms enable regulated production of meat and skins, protecting the wild population from poaching and giving even aggressive individuals a chance.
In our culture Crocodiles are aggressive predators, and are oen portrayed as villains in popular culture Tick Tock the crocodile In Peter Pan, the Disney adaptation of J.M. Barrie’s creation, Captain Hook is pursued relentlessly by the fearsome saltwater crocodile that ate his hand. Crocodile Dundee The 1986 film tells the story of Mick ‘Crocodile’ Dundee, inspired by the life of Rodney Ansell, who spent seven weeks stranded alone in the Australian bush. Jacala In Rudyard Kipling’s The Second Jungle Book, Jacala the crocodile is described as making a bellowing sound like a bull. However, Jacala is actually a mugger crocodile.
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© Alamy; FLPA; Peter Scott/The Art Agency; Thinkstock; Ardea;NaturePL.com Dr.jayan.d.; Ian Sutton; Lyndie Malan; Justin Welbergenus ;Cherubino;Lyndie Malan
Brackish water Saltwater crocodiles can survive in the open sea, but spend most of their time in slightly less-salty brackish water.
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Narwhals
MYSTERIES OF THE
Flip Nicklin/Minden Pictures/FLPA
Discover the secrets of these wondrous betusked behemoths living in the icy waters beneath the Northern Lights
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Sharks & Ocean Predators In the deep, cool waters of the frozen Arctic Circle lives an elusive creature that has long been the stuff of legend. Piercing the glassy surface of the waves, a giant needlelike tusk charges skyward, spiralling through the spray. Another follows this, and another, until the ocean’s icestrewn seascape is a pincushion of gently swirling spears. This display can only belong to one animal: a mottledgrey, ocean-going beast that is unique in the animal kingdom in so many different ways – the narwhal. Growing to around four to five metres (13.2 to 16.4 feet) in length with elegantly fluked tails, and living to around 50 years of age, narwhals are cetaceans, belonging to the same group as dolphins and porpoises. “They are Arctic whales,” explains Dr Martin Nweeia of Harvard School of Dental Medicine’s Department of Restorative Dentistry and Biomaterials Sciences. Dr Nweeia is the principal investigator for Narwhal Tusk Research, and he and his team have been studying these whales for over 14 years. This colossal tusk is what makes the narwhal look like nothing else in the ocean. Long, slender and with an anti-clockwise spiralling pattern that extends right to the tip, this is the very thing that has placed these marine mammals in the realms of fairytale and whimsy. The sword-like tusk is actually an overgrown tooth that protrudes out of the whale’s lip, made of similar stuff to our own pearly whites. “The narwhal has eight pairs of teeth that could form,” Dr Nweeia tells us. “But six of those [pairs] are genetically silenced at birth.” This means that they simply don’t ever develop. One set forms the tusks. “In the female [those teeth] typically are embedded in the bone, so they remain. You don’t see them, but they’re there. In the male the one on the right is embedded and the one on the left characteristically forms as the tusk. That being said, there are different expressions. Some whales can have two tusks. Some males may not have a
tusk and some females can have a tusk.” In the middle ages, narwhal tusks were thought to be able to cure ailments, possibly because they were touted and sold as mythical unicorn horns. It’s rumoured that in the 16th century Queen Elizabeth I purchased a narwhal tusk for £10,000 – the price equivalent of a whole castle. Theories behind the use of the tusk include spearing fish, regulating temperature, breaking ice, defending their young and as a dominance display in social hierarchies. “The most general one that is accepted, and still has validity, is that it’s a secondary sexual characteristic,” continues Dr Nweeia. This is a feature that distinguishes the sexes, but isn’t directly used in reproduction. Mostly male narwhals develop the tusk, so this is why the explanation fits well. Dr Nweeia and his team put tusk samples under the microscope to shed new light on their structure and function – what they found was staggering. Although the tusk can be all of the things suggested by many other scientists – a secondary sexual characteristic, a tool for defence or poking, a tool to break ice – there is one other job accomplished by the tusk that is far more important above all others. “This tusk is a giant sensor. It has the capability of understanding its ocean environment. That
ABOVE The team had to study the reactions of narwhals to certain stimuli to test the purpose of their tusks
NARWHAL Monodon monoceros Class Mammalia
Territory Arctic circle Diet Carnivore Lifespan 50 years Adult weight 1,600kg / 3,500lbs Conservation status
NEAR THREATENED
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Narwhals
How the tusk works
Far more than an overgrown tooth, the narwhal’s tusk is actually a highly receptive sensory organ, guiding the creature through the icy waters Spiral pattern All narwhal tusks spiral anti-clockwise, but scientists still don’t know why this is.
Cementum This calcified substance that covers the entire tusk is usually very tough, but in the narwhal it contains less mineral content and is flexible.
Peripulpal layer A unique feature in narwhal tusks, this layer is where the nerve cells that take information to the brain connect to the sensory tubules.
External conditions Thousands of tubule openings on the surface of the tusk are continually exposed to seawater and everything contained within it. Dentine This strong layer of the tusk contains protein, minerals and is also punctuated by millions of sensory tubules.
Sensing cells At the base of the tubule, these cells detect the changes and properties of the water near the tusk’s surface.
Tubule openings As many as 10 million tubules run from the centre of the tusk to the surface.
Nerve network Nerve cells contained within the middle of the tusk relay the information from the tusk to the brain.
Pulp This part of the tusk contains the nerve cells that transfer the sensory signals to the narwhal’s brain, enabling it to effectively read its environment.
ABOVE A microscopic view of the tubules on a narwhal tusk at 1,000x magnification strength
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Sharks & Ocean Predators was a critical piece because no one has really ever looked at this aspect, as a sensory organ.” When they examined the tusk up close, Dr Nweeia and his team found tiny tubes, known as tubules that run from the tusk’s nerverich core right through to the outer shell. These tubules are exposed to the seawater and send signals down the tubes, concerning the composition of the seawater, and what is in it, to special cells at the bottom. These cells process the information and pass it to the nerves, which then take this data up the tusk to the narwhal’s brain. In order to test this theory, the team travelled to the Arctic Circle to gather data from wild narwhal subjects. Dr Nweeia takes us through his technique for testing the sensitivity of the tusk: “After the narwhal was brought to shore, we would cover a half-metre section of the tusk with the tusk jacket and attach the heart- and brainmonitoring equipment to the whale. This was to observe brain and heart rate activity while we stimulated the tusk with solutions. Inside the tusk jacket, we would inject solutions of alternating high salt and fresh water, while monitoring the whale’s reaction.” This typically took around 20 minutes, with minimal stress on the whale. “On any field expedition, we would catch and release about five to eight whales to enable sufficient samples to be analysed,” Dr Nweeia continues. While working in the field, the team also gathered traditional knowledge from the people who know the narwhal most intimately, the Inuit of Nunavut. As the only permitted hunters of the narwhal, Inuit elders have grown to know the movements of these cetaceans incredibly well. Sharing this knowledge was essential to understanding the subtleties of narwhal behaviour and to dispel the myths about these fascinating whales. For example, the Inuit were able to tell Dr Nweeia another interesting reason for the narwhals to visit the inlets of Hudson Bay during the summer. “Narwhals come to these inlets to molt,” he says. “It has never been witnessed by scientists, since the hunters describe the molting to be a gauze-like layer that quickly dissipates in the water, unlike the beluga molt that’s heavier and much easier to observe.” A molt is when the whale sheds its outer layer of skin, and the fact that narwhals do this may never have come to light if it weren’t for the indigenous Inuit people sharing their experiences with Dr Nweeia and the other scientists.
Another shocking discovery that Dr Nweeia himself admits truly surprised him was a piece of information shared by local Inuit hunters. “When you typically see [narwhal tusks], they are dried out, so they’re quite rigid,” he begins. “We were talking to a lot of elders and hunters about whales and insights were passed on to us. The information from them was critical. They would tell us that when these whales swim, this [tusk] is movable. It can actually flex back and forth.” Dr Nweeia says, “Quite honestly when I looked at that, as a scientist, I thought ‘I don’t think so.’” After looking into it a little further, the team found this was the case, and the narwhal’s tusk is a flexible organ. “I found it hard to believe!” reveals Dr Nweeia. “They hypothesised that a 2.7-metre (nine-foot) section of tusk had the capability of going 0.3 metres (one foot) in any direction. Which shocked us all!” Dr Nweeia and his team were able to prove that the tusk is far more than just a toothy outgrowth, and is an essential sensory organ that could change the way we understand narwhals and their behaviour forever.
ABOVE Though no one is entirely certain of the full use of the narwhal tusks, they also feature in fights between rivals
How animals use their tusks
Elephant
Walrus
Hippo
Babirusa pig
These tusks are actually elongated incisors, present in both males and females. They’re used for numerous tasks, including clearing paths, digging for water or roots and fighting between rivals.
Walrus tusks are elongated canine teeth that never stop growing. They can reach up to a metre (three feet) and are used for breaking through sea ice or hauling themselves onto the shore.
Inside these gigantic jaws, the canine tusks can grow up to 50 centimetres (20 inches). Not famed for being the friendliest animals, hippos can use their tusks to fight with other males.
This wild boar grows two sets of tusks. The upper canines grow up through the skin of the snout from the inside. If the tusks aren’t ground down, they can curve around to touch the forehead.
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Narwhals
Never giving up: the man behind the research
What were the conflicting ideas that made you want to clarify the role of the tusk? Well there’s about every theory you can imagine to explain them, but the most general one that is accepted, and still has validity by the way, is that it’s a secondary sexual characteristic. Certainly there’s nothing wrong with that, but [it] only explains a certain level of understanding… Rather than just kind of pushing it off, one has to think: ‘Why make this decision as an animal? What in evolution decided to go this route?’
Do we know whether or not narwhals act in the same way as other cetaceans? They are very social like beluga. Narwhals have a large vocal range and they also have a strong social network. Certainly in the work that we’re doing, we do brief capture and release of whales, and we have both a veterinarian and often go with the VP of the Vancouver aquarium… Both of these people are very sensitive to aspects of social interaction, because typically they do work with belugas a lot. Interestingly enough, if in our catch and release programme we catch one member of a family, the team is very sensitive to the fact that often other members of the family will stick around until their partner comes back.
Where did you start with dispelling the myth of the mysterious narwhal tusk? It was certainly a long process, but my starting point was very distinct for me. I made an appointment with James Mead, then the curator of marine mammals at the Smithsonian Museum – regarded as one of the most prominent marine mammal anatomists in the world today… I remember at a distinct point of the conversation when I had questioned the function of this tusk, he looked at me and he said: ‘Oh I thought this was pretty well understood as a secondary sexual characteristic, like the peacock feather and the lion mane,’ and I remember looking at him directly… I said: ‘Yeah and nobody knows
what those do either!’ I could see him smile, because in the moment there was an understanding that, whatever you study and whatever you look at in life, it doesn’t matter whether it’s a tusk or a personal relationship of any other attribute of life, your level of really understanding something is really only proportional to your curiosity.
Not all narwhals have tusks, so how do we know which individual gets one? We are actually doing a large genetic study at the moment… The thing that we found in our most recent paper is that this tusk is a giant sensor – it has the capability of understanding its ocean environment. That was a critical piece because no one has really ever looked at this aspect, as a sensory organ. It may have significance in terms of sexual selection… it may help determine the fitness of the species, so for example if the tusk senses certain kinds of fish that would be important for newborn calves to have, that would demonstrate fitness to the female, so those kinds of things. But likewise, there still may be a social hierarchy standpoint. People have hypothesised that while the secondary sexual characteristic is used so males can fight it out for who gets the female, but nobody has ever witnessed on a common level any aggression between males. It’s been hypothesised, but it’s [only rarely] been seen [and] when it has been seen it’s very isolated. You could see a rogue male going off and doing something but it’s not typical in the species to do that. The last thing you want to do is break that tusk.
BELOW Scientists have to be careful to cause as little distress to the animals as possible as they do tests
© Corbis, Getty, Thinkstock, Glenn Williams, Narwhal Tusk Research; Joseph Meehan, Doc White, Gretchen Freund, Isabelle Croc, Anthony Giusepetti, Kevin Hand
With a background studying particular characteristics and features of animals and humans, as well as a clear passion for the narwhal, expert and scientist Dr. Martin Nweeia took a fresh approach to the mystery of the whale’s tusk. Having studied the creatures for some 14 years, he has a new light to shed on the unusual-looking creature
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Polar bears
An animal synonymous with frozen winters and Arctic wastelands, these mighty hunters are perfectly equipped to hunt in the wild oceans
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Sharks & Ocean Predators “The main threat to these majestic bears is the encroaching of human civilisation on their home and, most importantly, climate change”
Powerful senses of an oceanic giant Impeccable senses to conquer the most inhospitable environment on Earth Deceptively fluffy, the polar bear is the fearsome king of the Arctic and is top of the polar food chain. Found across the Arctic Circle, there are around 19 populations of polar bears living in four different ice regions of the Arctic. These bears freely roam the ice around the fringes of the polar basin, and although they stay in their home ranges, some can wander for miles. Polar bears depend on the sea and its ice for food. These bears eat a diet rich in fat, consisting mainly of seals – their favourite flavour being ringed or bearded seal, which are rich in blubber. However, bears will also take opportunistic meals, and feast on Arctic birds, eggs, sometimes whales, and even the odd caribou. These fierce hunters use their powerful sense of smell to locate
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breathing holes that seals cut into the ice. The seals will surface every 5 to 15 minutes to, and this is when the bear strikes. Bears even stalk the seals as they bask on the ice, creeping closer and closer before pouncing on their prey. As primarily solitary beasts, polar bears differ greatly with their social interactions. Although not territorial, some will be very wary or aggressive to other bears when they approach, but others will greet the new bear like an old friend and play for hours. As such, these bears show distinct personality traits and individual preferences. The main threat to these majestic bears is the encroaching of human civilisation in their home and, most importantly, climate change. This is at its extremes in the poles, with the Arctic sea ice’s minimum summertime coverage reducing by 12 per cent per decade for the last 30 years.
Polar bears
POLAR BEAR Ursus maritimus Class Mammalia
Territory Arctic Circle Diet Seals Lifespan 25-30 years Adult weight 410-720kg / 900-1,600lbs Conservation Status
VULNERABLE
Dangers of growing up in the Arctic It’s a tough job being a polar bear cub, with a plethora of Arctic obstacles to overcome. Cubs rely on their mother and instinct to help them survive
Life at sub-zero Cubs are born in November and December, and Arctic winter temperatures can drop to −50°C/−58°F. For a very little bear that’s a chilly start to life! Luckily, the snow den that the mother builds is insulated, creating a snug haven for cub development.
No choice but to swim in icy water Bear cubs are introduced to water at a young age, but as the ice becomes sparse, cubs have to follow their mother on longer, incredibly exhausting swims. Small bears have less blubber, meaning less insulation and buoyancy in the chilly Arctic waves.
Predators on the prowl Once the bear cubs poke their tiny white snouts over the threshold of their mother’s snow den, they could face hungry animals much bigger than them looking for a quick meal. The main threat is from fully grown male polar bears.
Global warming melts polar bears’ homes Retreating sea ice can mean a potential lack of food. Mother bears need to keep their energy intake up to provide very young cubs with rich, nutritious milk, while bigger cubs need to learn how to hunt. Without sea ice there’s less seal fishing to be done, which limits the bears’ diet.
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Eating for survival These arctic giants rely on the best-possible diet to help see them through such extreme conditions Polar bears need to maintain their thermal fat layer to battle the cold, and seal blubber contains 70 per-cent energy-packed fat, rich in healthy oils and vitamins. Seals are abundant in the Arctic circle so they are a logical choice, and with 42 sharp teeth the polar bear has little trouble killing a meal. The hunting skills of polar bears range from a silent sneak attack to an outright charge, so no seal is safe.
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Polar bears
What polar bears eat
11% other (e.g. whale carcasse)
13% bearded seals
63% ringed seals
13% harp seals
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Arctic adaptations Polars are kitted to the brim with tools to tackle the harsh environment The polar bear’s adaptations to deal with the cold go beyond their furry outward appearance. Polar bears have evolved to have reinforced heart muscle that fights against vascular disease, much more so than their grizzly bear relatives. A strong heart helps pump warming blood around the body, which is insulated by more than thick fur. A polar bear’s skin, bone marrow and the space between organs is packed with adipose fat that is bursting with stored energy. This specialised fat can make up over 50 percent of the polar bear’s body weight and keeps their body functioning properly despite the bitter cold. Polar bears often have to fast when food is scarce or when raising cubs, so this energy store is essential to their survival. These bears can even control the activity of their cells to raise their body temperature. Nitric oxide found in the body converts nutrients from food into energy, but polar bears can opt to convert ingested nutrients directly into heat by controlling the level of nitric oxide in their cells. Every part of a polar bear’s body can be used as a weapon against the cold, and their unbelievable adaptations to dealing with plummeting temperatures are still not fully understood. As polar bears grow they’re able to eat a more varied diet of larger animals. Older bears eat enormous harp seals and even beluga whales to sustain their bulk. Males can grow to double the size of females, and the bigger they get the more they need to eat to keep their temperature up. The stomach can hold 20 per-cent of their body weight, which is 700 kilograms (300 pounds). That’s the equivalent of an average human eating 1550 loaves of bread!
Colourless hair The outer layer of a bear’s fur is actually colourless – these hairs are hollow and reflect visible light in their empty space, which makes the bear look white and provides a handy camouflage for hunting.
Black skin Beneath the white fur, a polar bear’s skin is actually black. This helps to absorb the Sun’s rays and retain the heat. White skin that would reflect heat off the bear’s body.
Furry feet The bottom of a polar bear’s paws is covered in fur. This helps to insulate and provide grip. Traction for charging about on the ice is also provided by small bumps on the pads, known as papillae.
Little ears and tail Having smaller extremities conserves heat and small ears and tail lie close to the body. This doesn’t affect their function though – they have very acute hearing!
Thick blubber A ten-centimetre layer of fatty blubber just under the skin acts as an insulator. It also provides buoyancy in the water to save energy when swimming.
Super-sized paws Huge oar-like paddles for paws are efficient and energysaving when swimming, and spread the bear’s weight while on the ice. Strong, sharp claws help to grip.
The bear family 1 metre
A glance at the biggest bears in the business
Giant panda Ailuropoda melanoleuca Length: 1.5m (plus 0.2m tail) Shoulder height: 1m Amount left in wild: 1,400
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Sun bear Helarctos malayanus Length: 1.2m Shoulder height: 70cm Amount left in wild: no reliable data
American black bear Ursus americanus Length: 1.8m Shoulder height: 1m Amount left in wild: 850,000-950,000
Polar bears “The polar bear’s huge paws act as oar-like paddles in the water for efficient, energysaving swimming”
The polar bear’s closest relative Polar bears are descended from brown bears – a species that is clearly much more at home in the forest than in the Arctic Circle. Fossil evidence shows that the
polar bear may have evolved as long as 1.5 million years ago. However, the two species are still so similar that they have been known to interbreed, even in the wild.
Streamlined form Polar bears have longer necks and narrower skulls than brown bears – an adaptation for their marine lifestyle making it an efficient and streamlined swimmer Long, curved claws Brown bears’ claws are much longer than the polars’; they can be the length of a human finger. Brown bears use these for digging dens and rooting out vegetation Shoulder hump Brown bears have a prominent shoulder hump – muscle mass that allows it to be a powerful digger. While polar bears do dig dens in snow, they don’t have humps
Asiatic black bear Ursus thibetanus Length: 1.8m Shoulder height: 1m Amount left in wild: 60,000
Spectacled bear Tremarctos ornatus Length: 1.5m Shoulder height: 80cm Amount left in wild: Less than 6,000-10000
Sloth bear Melursus ursinus Length: 1.8m Shoulder height: 90cm Amount left in wild: 7,000-10,000
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Learning from the best How a mother prepares her cubs for the cold reality of their extreme environment When a female polar bear becomes pregnant she builds an underground burrow, where she will wait for two or three months to give birth to one or two tiny cubs. Weighing only 500 grams (one pound), cubs will suckle from the mother for the following four months until they reach weight of 10 kilograms (22 pounds). The milk the mother provides is 27 per-cent fat that helps the cubs bulk up for the day they leave the den. When the cubs have gained enough insulating weight the mother leads her cubs up to the surface, where she immediately begins to search for a meal. She will not have eaten since entering the den six to eight months previously, and she needs to teach her cubs how to survive in their first moments above the ground. The mother keeps her cubs by her side while they practice their hunting and survival skills for up to three years until she is satisfied they are ready to fend for themselves, and sometimes that moment comes sooner than expected. Cubs can be left orphaned, and if this happens they need to be prepared to face the Arctic tundra alone. Cubs may flee from their mother is she is fatally attacked and go in search of food for themselves. If their mother has taught them well, the cubs are able to survive to go on to reproduce in the future. The area the mother first teaches her cubs how to hunt becomes their home for life, and future generations will raise their own cubs in the same place.
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“The mother keeps her cubs by her side while they practise their hunting and survival skills” 149
©Thinkstock, Alamy, Rex Features
Polar bears
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50 FACTS ABOUT EXPLORE SOME OF THE MOST AMAZING HUNTING AND LVING HABITS OF THESE FANTASTIC FLIGHTLESS BIRDS
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Penguins
1. The emperor penguin breeds at -60°C If there is one fact above all others that pays testament to Aptenodytes forsteri how amazing penguins are, Class Aves it’s that emperor penguins breed at -60 degrees Celcius (-76 degrees Fahrenheit), a feat that would be simply Territory Antarctica unthinkable and impossible Diet Carnivore Lifespan 15-20 years for any other species on Adult weight Up to 40kg / Earth. This flightless bird, 88lbs which is native to the coldest, Conservation Status driest and windiest continent on Earth, Antarctica, braves an environment where, with NEAR THREATENED wind chill taken into account, the temperature can plummet to insane levels of cold. Don’t think that such cold conditions are experienced only rarely by the emperor, as the average temperature in Antarctica is consistently around -30 degrees Celcius (-22 degrees Fahrenheit), while the coldest temperature ever recorded in the emperor’s natural habitat stands at -89.2 degrees Celcius (-128.6 degrees Fahrenheit). What makes this feat even more astounding, however, is that emperor penguins spend the entirety of the long winter months in Antarctica on the open ice, completely exposed to the elements. The female of the species breeds directly into this cauldron of cold, before leaving the tiny vulnerable young to be sheltered by the male partner. They will then proceed on a hunting trip that lasts two months and can see them travelling over 80 kilometres (50 miles) away from their partners and young. The female will only return once her belly is stocked to the gullet full of fish, squid and other marine creatures. If she’s lucky the male EMPEROR PENGUIN
Antarctica
Emperor penguin range emperor will not have starved to death and the chick will have survived the extreme environment relatively unscathed, but incredibly hungry. Emperor penguins possess many amazing features and abilities, many of which we’ll explore here. However, this ability to withstand the worst, most brutal climate and environment the Earth can muster for months on end, without food and with newborn young to protect, is the most jaw-dropping of them all.
BELOW RIGHT A penguin chick has to survive harsh conditions in order to survive into maturity BELOW LEFT An example of a penguin huddle, where the birds gather together to stay warm
Blizzard Emperor penguins live in Antarctica and, as such, have to endure temperatures of -60° C (-76°F) and frequent bone-freezing blizzards.
Huddle To survive and breed in such harsh conditions, emperor penguins huddle together in groups, with those directly in the wind blast continuously rotated.
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Sharks & Ocean Predators 3. They are able to drink salt water
2. Penguins have 70 feathers per square inch As penguins spend so much of their time in water, they need a reliable waterproof coating, which for all species comes courtesy of their feathers. In fact, these are some of the most dense and numerous plumages of all birds. The average feather count per square inch (6.5 square centimetres) of a penguin is 70 and with some species, such as the emperor penguin, that number rises to more than 100. These small, stiff and tightly packed feathers overlap and when in good condition not only help insulate the bird against its cold environment but ensure a waterproof barrier is maintained at all times, enabling the penguin to slip through the water effortlessly before returning to land in a fast-drying state. On the rare occasion that a penguin gets too hot, it cools itself by raising its flippers, which are the one part of its body, aside from the feet, where its plumage is not so dense and heat can escape quickly.
Another unique evolutionary feature possessed by all penguin species is the ability to drink salt water without any adverse side effects. Humans and most other land-dwelling animals cannot drink ocean water due to its high salt content, but penguins have evolved a special supraorbital gland that filters all salt intake from its bloodstream, enabling it to drink and be refreshed as if drinking from a freshwater source. The filtered salt, once extracted and separated from the animal’s bloodstream, is then eventually excreted as a concentrated fluid from the penguin’s nasal passages.
Warm coating Feathers keep penguins warm in freezing temperatures, but also maintain a waterproof barrier for swimming.
BELOW Penguins are able to consume salt water, without any adverse effects
“The penguin varies its blood flow rate by adjusting the diameter of its arterial vessels” Heat exchangers A system of arteries exchanges heat to keep the extremities as warm as possible.
Arterial vessels The penguin is able to adjust its blood flow rate to suit the changing conditions.
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4. They can control their blood flow Ever wondered why parts of a penguin don’t just freeze and fall off in the harshest climate on Earth? Well, the answer is due to the ability to control its own blood flow, which is certainly a handy trait when living in such typically cold climates. The penguin varies its blood flow rate by adjusting the diameter of its arterial vessels, supplying its blood in accordance with climate conditions. In cold conditions the diameter is reduced to limit the blood flow (which reduces heat loss) and in warmer conditions the diameter is expanded, increasing the flow. Partnering this ability, which is controlled with a complicated nervous and hormonal system, are also countercurrent heat exchangers, which are positioned at the top of the penguin’s legs and exchange heat from warm blood travelling in one direction with cold blood travelling in the other. This ensures that heat is distributed efficiently around the body and that minimal loss occurs at the extremities, while ensuring they don’t freeze.
Penguins 5. They molt at an unusually fast rate Not many people are aware that penguins, like all birds, molt their feathers. In the penguin’s case, molting generally occurs annually and all in one go, which is referred to as a catastrophic molt. This results in each species completely shedding its outer layer of feathers quickly and with spectacular results, with a penguin mid-molt looking like an exploding pillow.
6. Males and females look identical Most penguin species are not sexually dimorphic. This means that both the males and females are identical in appearance with regards to both their plumage and colouration.
7. They do not have teeth Rather than teeth, a penguin has hundreds of spines on the top and bottom interior of its beak. These spines help the penguin hold slippery, moving prey, particularly fish.
8. Every penguin lives in the Southern Hemisphere Every species of penguin lives in the Southern Hemisphere, ranging from the continent of Antarctica through to the relatively warmer waters of the Galapagos Islands.
9. The Magellanic is named after Ferdinand Magellan The Magellanic penguin (Spheniscus magellanicus) was named by its discoverer, Portuguese explorer Ferdinand Magellan. The adventurer stumbled upon the species in around 1520 CE, along with a range of other species that had gone undiscovered.
10. The Little Penguin is 13 inches tall
The littlest penguin The Little Penguin’s small size oen leaves it vulnerable to predators such as lizards, stoats and even pets.
Penguins on average measure between two Eudyptula minor and three feet in height, Class Aves but this figure means nothing to the Little Penguin – a species that averages a paltry Territory South coast of 33 centimetres (13 Australia, coastal New Zealand inches) in height when Diet Carnivore Lifespan 6-7 years fully grown. Adult weight 1.5kg / 3.3lbs Due to its small size, Conservation Status the Little Penguin is often also commonly referred to as the LEAST CONCERN fairy penguin, with the animal’s small size and low weight – individuals struggle to break 1.5 kilograms (3.3 pounds) – granting them a cute and friendly appearance. Like most seabirds Little Penguin have a long lifespan, with the average being 6.5 years. The Little Penguin was first discovered and recorded in 1781 CE and today is a well-established species, with 350,000-600,000 individuals estimated to exist in their natural habitat. Indeed, the little penguin population is well dispersed, with the animal found on New Zealand, Australia, the Chatham Islands, as well as some sightings in Chile and Australia even sporadically in South Africa. Unfortunately, however, due to this species’ establishment on national mainlands, they are frequently killed by cats, lizards, foxes and stoats. These attacks typically come when Little Penguin range the little penguin is at its on-shore nest, which it returns to each evening with food harvested from the ocean. LITTLE PENGUIN
11. They toboggan when leaving the water All penguin species are capable of tobogganing, which is essentially where the bird lies on its stomach and propels itself horizontally across the ice, with its flippers and feet acting as the propelling mechanisms. Tobogganing is not only a much faster form of travel for penguins – whose large bodies, short legs and webbed feet make walking cumbersome – but it also helps the animal conserve more energy, which is so precious in its oen unforgiving habitat. Penguins are capable of sliding with minimal effort across flat or descending inclines. They even use RIGHT When this tobogganing method to quickly penguins toboggan, escape predators such as seals and they are not only conserving energy, sea lions, who don’t posses the same but can also evade ability and so cannot keep up with predators much faster their prey. than by waddling
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12. The macaroni is the most common species With an estimated 20 million individuals in Eudyptes chrysolophus existence, the macaroni Class Aves penguin is the most numerous penguin species living on Earth and millions of birds Territory Subantarctic occupy a range that Diet Carnivore stretches from the Lifespan 15-20 years Adult weight 15.5kg / 12lbs subantarctic to the Conservation Status Antarctic Peninsula. To be precise, at least 216 colonies have been VULNERABLE identified at over 50 different sites around the world. The macaroni penguin can be found from Chile, through the Falkland Islands and onto the South MACARONI PENGUIN
Shetland Islands among many others, with the animal spreading far and wide – especially during foraging trips – and frequently coming into contact with scattered human settlements. Aside from its high numbers, the macaroni penguin is also known for its remarkable fasting behaviour. During the species’ breeding period the male fasts for around 37 days after the arrival of the egg, before swapping with the mother for a ten-day period to forage, while the female then fasts for 42 days straight. When the male eventually returns from foraging, it then proceeds to fast once more for a similar time frame. Due to this extensive fasting habit, both male and female macaroni penguins lose between 35 and 40 per cent of their total body weight during the hatching and raising period.
“Macaroni penguins lose between 35 and 40 per cent of their total body weight during the hatching and raising period”
Widespread species Macaroni penguins living on the snow-covered slopes of Cooper Bay, South Georgia.
Bluish-black plumage The macaroni has a black plumage with a bluish sheen when new and a brownish sheen when old, just prior to molting.
Crested species The macaroni penguin is one of six species of penguin with a crest. This stretches from the centre of the forehead to the nape.
13. 1 in every 50,000 penguins is born with a unique brown plumage Around 1 in 50,000 penguins is born as an isabelline penguin. These unique and rare penguins are marked due to their distinctive brown plumage, which is caused by a similar biological process to albinism. Unfortunately, due to their brown plumage standing out against the animal’s native LEFT Isabelline penguins are extremely rare and also have a shorter life expectancy
backdrop of ice and snow, therefore offering no camouflage against predators, these isabelline variants tend to have shorter life expectancies than regular penguins. Additionally, even if an isabelline penguin somehow survives against predation, it oen then finds it difficult to mate, with the other penguins with normal plumage overlooking it when the breeding season arrives.
14. They are able to consume stones to aid with digestion Scientists believe penguins will actively consume small stones along with food to aid digestion within their stomach. The stones are also believed to add weight and aid the birds’ diving.
15. An emperor egg takes 67 days to hatch As you may expect, the largest penguin species in the world – the emperor penguin – has the longest incubation time in-egg than any other, with it taking over two months for any chick to hatch into the world.
16. Most species lay two eggs at a time All penguins, aside from the emperor and king species, tend to lay two eggs in a nest made of stones, bones and moss. The emperor and king penguins only ever lay one, however, and don’t build nests but incubate the egg on the tops of their feet to keep them from the cold floor.
17. Penguins breed during spring and summer Aside from the emperor penguin, which breeds during the cold of the harsh Antarctic winter, all other species of penguin breed during the spring and summer months, when generally conditions are a lot warmer.
18. Male emperors make very good fathers As soon as a female emperor penguin produces an egg, the male partner immediately takes over the caring duties, incubating the egg carefully on the top of his feet. While he’s doing this, the female emperor travels away on a hunting and feeding trip.
Penguins
19. The gentoo can swim at up to 22mph Faster than any other diving bird, the gentoo penguin is distinctive for many reasons, primarily for its ability to swim at a rapid 22 miles (36 kilometres) per hour. It’s also notable due to its flamboyant red-orange beak, white feathered caps and super-streamlined body, with this species type commonly found throughout the Antarctic Peninsula and its many icy islands. On land, gentoo penguins have no natural predators, but despite their speed in the water they are frequently preyed upon in the oceans by leopard seals, sea lions and orca whales. Additionally, during the breeding season, their eggs are prone to be taken by birds of prey such as caracaras and skuas. This predation, along with climate change and human fishing operations, has seen the number of gentoo penguins decrease rapidly over the past couple of decades, with the species receiving a Near Threatened rating by the IUCN Red List in 2007. This is particularly depressing, as the gentoo is one of the cornerstone penguin species, being the third largest (76 centimetres or 30 inches) in height and weighing a modest 5.5 kilograms (12 pounds). Adult gentoos spend most of their days hunting close to shore, where they consume large quantities of squid and krill. Gentoo chicks take just over a month to hatch and then a further month of direct care before they can leave the nest.
20. A penguin’s body temperature is 38 °C The average temperature in a penguin’s body is 38 degrees Celcius (100 degrees Fahrenheit), even despite most living in subantarctic conditions, where temperatures oen plummet well below -20 degrees Celcius (-4 degrees Fahrenheit). Interestingly, however, scientists have used infrared imagery to show that at times parts of a penguin’s body can drop in temperature by over 15 degrees Celcius, with inactive extremities kept cooler than the core. This helps the penguin conserve energy that otherwise would have been wasted.
Staying warm Though they live in cold conditions, penguins can still remain warm.
Acrobatic Gentoos are also one of the most agile penguins and are capable of leaping high out of the water.
Rapid swimmer While swimming under the water gentoos can hit 22mph (36km/h).
GENTOO PENGUIN Pygoscelis papua Class Aves
Territory Subantarctic Diet Carnivore Lifespan 10-15 years Adult weight 5.5kg / 12lbs Conservation Status
NEAR THREATENED
“Adult gentoos spend most of their days hunting close to shore” “The emperor penguin can dive down to 1,700 feet” 21. They aren’t able to breathe underwater Despite spending the majority of their lives there, penguins can’t actually breathe underwater, with the time and depth they can be submerged for being wholly dependent on the species type. As an example, little penguins can only manage to dive down to around 60 metres (200 feet) and remain underwater for up to a minute. In contrast, the emperor penguin can dive down to 565 metres (1,850 feet) below the surface and may remain there for around 20 minutes at any one time.
22. They are a very sociable species
Toasty seat Penguin chicks can perch on a warm pair of feet to avoid the cold snow.
Despite their remote habitats and general lack of contact with the wider world, penguins are social animals, conducting almost every aspect of their daily lives together. From diving and hunting, through to breeding together in large colonies and communicating with one another constantly via calls, as well as visual displays, penguins are always in contact. They even travel and sleep in groups too – the latter oen to increase safety and warmth – and will band together to fight off predators who are trying to capture a younger or weaker individual.
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23. Penguins are carnivores It’s easy to forget, but all penguin species are actually piscivorous carnivores, consuming massive amounts of meat during their lives. In fact it’s estimated that the Earth’s macaroni penguin population consumes 9.2 million tons of krill each and every year. While penguins consume a wide variety of food sources, they do have some favourites, with krill, squid and fish such as anchovies and sardines common favourites. Certain species also have a penchant for crustaceans, cuttlefish and shrimp too, eating and
digesting them directly or consuming and processing them into a slurry to be more easily transferred to their young. Hunting for meat occurs on a daily basis and trips are undertaken in groups, but foraging itself can occur both in isolation or as part of a concerted group effort. They work together to catch prey or take it in turns to enter the water while the others rest. Penguins’ desire for meat will see hunting parties frequently travel many miles both in and out of water to reach prime feeding grounds, spending days on end catching and eating fish.
Blood-thirsty Penguins are carnivores, consuming fish, shellfish and crustaceans in very large quantities to survive.
Hunting technique A popular hunting technique is to dive to 50m (164) and then swim up to surprise fish swimming closer to the ocean surface.
“Penguins’ desire for meat will see hunting parties frequently travel many miles” 24. They are extremely short-sighted
LEFT Penguins have similar eye structures to humans
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Intriguingly penguin eyes and human eyes are remarkably similar, with a cornea, iris and crystalline lens focusing light onto a retina. With penguin eyes, however, the cornea is almost flat and its iris is controlled by a far more powerful muscle than ours – two features that make the penguin capable of seeing both in and out of water equally well (unlike humans who are farsighted underwater). The trade-off for this ability is a general shortsightedness both in and out of the water, however, particularly so when on land. Regardless, with little need for pin-sharp, hawk-like vision, penguin eyes have been shown to be completely adequate. In general, individuals are easily able to pick out partners and chicks at medium range.
25. Their colonies can be massive If you thought a penguin rookery was big, with thousands of birds all drawing together in one place, then think again, as a penguin colony can be over 100-times larger. The current Guinness World Record for the largest penguin colony on Earth lies with Zavodovski Island, an active volcano in the South Sandwich Islands. Zavodovski sees approximately two million chinstrap penguins breed on its slopes each and every year, with several hundreds of thousands of birds descending on the island to court and mate. Along with the macaroni, the chinstrap penguin is among the most numerous penguin species found across the world.
Penguins 26. The word penguin was first used in the 16th century The word penguin was originally created as a synonym for the extinct great auk in the 16th century. It is believed the word stems from the Latin ‘pinguis’, meaning ‘fat’.
27. The gentoo has a brightorange bill Gentoo penguins are easily identifiable due to their brightorange bill, which no other species has. They also have the biggest tail of all penguins
28. They enter the water in groups Penguins tend to jump into the ocean in large groups. Researchers believe that this habit is an evolved behaviour to aid survivability and increase safety from predators.
29. Megadyptes antipodes has yellow eyes Megadyptes antipodes (yelloweyed penguin) is easily identifiable purely by the colouration of its eyes, which stand out as a bright greenish-yellow. This species is found only in New Zealand.
LEFT Penguin colonies can include many hundreds of thousands of individuals, all in one place
30. A nest area is called a rookery As social birds, penguins mate together en-masse in large breeding grounds referred to as a rookeries. It’s here that penguins construct their nests and incubate their young, with each nest being a specified distance from its neighbour. Rookeries frequently contain thousands of birds all tightly packed in one place and, as such, each penguin develops its very own unique call that it can use to find its partner or chick, even amid the throng. By nesting together in a rookery rather than on their own in isolation, penguins also help defend one another against predators.
31. Each species has a distinctive call Penguin calls may sound the same but each one is identifiable, with a single penguin amid thousands of others capable of recognising its mate. As penguins are nearly identical, these vocalisations play a crucial part in their lives. There are three main types of penguin call: the contact, display and threat calls. The first assists a penguin in recognising other colony members and it’s typically very loud, with the contact calls of the larger penguin species, such as the emperor and the king, travelling over a kilometre (0.6 miles). The display call is used between penguin partners and differs to the simpler and loud contact call in that it’s far more complex, conveying information on territorial placement, sexuality and individual recognition. The threat call is the simplest penguin vocalisation of the three and is used to warn other colony members of predators.
Safety in numbers Penguins nest in close proximity in order to protect one another from potential threats
LEFT Penguins rely on their calls to warn of danger as well as identify nests
32. There are 16 species of penguin, 15 of which are now endangered Sadly, over two-thirds of all penguin species are currently rated as Near Threatened, Vulnerable or Endangered by the International Union for Conservation of Nature (IUCN). Climate change and human fishing activities have been highlighted as the main factors that are driving them towards complete extinction. A recent study by the World Wide Fund for Nature predicted that, thanks to the aforementioned threats, emperor and adelie penguins will experience a steady decline in population size by 50 and 75 per cent respectively over the next 40 years, making present conservation efforts all the more vital.
Emperor Aptenodytes forsteri
Macaroni Eudyptes chrysolophus
Little Penguin Eudyptula minor
Chinstrap Pygoscelis antarctica
African Spheniscus demersus
Gentoo Pygoscelis papua
King Aptenodytes patagonicus
Humboldt Spheniscus humboldti
Adelie Pygoscelis adeliae
Fiordland Galapagos Eudyptes Spheniscus pachyrhynchus mendiculus
Yellow-eyed Megadyptes antipodes Snares Eudyptes robustus
Magellanic Rockhopper Eudyptes chrysocome Spheniscus magellanicus
Erect-crested Eudyptes sclateri
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33. The yellow-eyed penguin is the rarest So endangered that a dedicated conservation organisation has been set up for it, the yellow-eyed penguin is the Earth’s rarest species of penguin, with around 5,000 individuals extant and 2,000 breeding pairs left in their native habitat. Despite being unique to New Zealand, human development and interference has left the yellow-eyed now most numerous on the country’s southern-most islands. Yellow-eyed penguins hunt for food primarily over New Zealand’s nearby
continental shelf, which lies roughly 1.6 kilometres (one mile) offshore and extends out to 25 kilometres (16 miles). Like all penguin species, their diet largely consists of fish, which the yellow-eyed harvest by diving down to 120 metres (394 feet) into the ocean waters. They are also among the longest living penguin species, capable of hitting 20 years in age. Males tend to live longer than females, leaving the species with a male-to-female ratio of 2:1 after about ten years of age.
34. The emperor stands over a metre high The largest penguin species is the emperor penguin, which averages 1.15 metres (3.8 feet) in height, but can oen surpass a whopping 1.3 metres (4.3 feet), with these giants towering over lesser species with ease.
35. They mainly walk at two miles per hour Almost all penguins waddle at around 3.2 kilometres per hour (two miles per hour) on land. However, this rule is broken by the king penguin, which has a different gait and can walk at up to 5.6 kilometres per hour (3.5 miles per hour).
36. Only the adelie and emperor actually live in Antarctica While penguins are oen thought to inhabit Antarctica exclusively, only two types live on the continent proper, with the emperor and adelie species braving its extreme climate. Older and wiser The yellow-eyed penguin is also one of the longest living penguin species, frequently surpassing 20 years in age.
New Zealand
YELLOW-EYED PENGUIN Megadyptes antipodes Class Aves
Yellow-eyed penguin range
“They are also among the longest living penguin species” 158
Territory New Zealand Diet Carnivore Lifespan 10-20 years Adult weight 5-8kg / 11-18lbs Conservation Status
ENDANGERED
37. Chicks are not waterproof
38. A wild penguin lives up to 20 years In the wild penguins live to between 15 and 20 years, however in captivity that number is closer to 30 years. The official record for the oldest captive penguin is 29 years, four months.
39. All the subspecies lay eggs on land Despite all penguin species preferring a water habitat, they always return each year during breeding season to lay their eggs on land, which take between 32 and 68 days to hatch.
40. A group of young chicks is called a creche Penguin young sometimes group together in what is referred to as a creche. A group of fully grown penguins, however, is referred to as a ra.
41. The chinstrap is the most aggressive Chinstrap penguins not only fight fiercely with one another during the breeding season, but also engage in thieving behaviour, oen stealing choice pebbles from rival nests, to supplement their own homes.
Adult penguin plumage isn’t acquired until a year aer birth. Until then the chicks have thinner and less waterproof plumage.
42. They cover their feathers with a protective oil All penguins have evolved a feature that helps them care for and maintain their feathers. Each penguin comes packing a uropygial gland, a special oil-producing gland near the animal’s tail feathers that it can harvest with its beak and then spread over its body. This oil acts as an extra barrier for the penguin, protecting its feathers from damage and ensuring its plumage remains dry. The activity of harvesting the gland and covering the feathers is referred to as preening, with penguins spending parts of each day working on their feathers. If a penguin works on another’s coat it’s referred to as allopreening.
LEFT In order to stay smooth in the water, a penguin can produce an oil to spread over its body
Penguins 45. They swim at six miles per hour On average penguins swim at six miles (9.7 kilometres) per hour, however when hunting or being chased by predators this spikes massively, with certain species frequently hitting over 20 miles (32 kilometres) per hour.
46. Humans ate penguins KING PENGUIN Aptenodytes patagonicus Class Aves
Territory Subantarctic islands Diet Carnivore Lifespan 15-20 years Adult weight 11-16kg / 24-35lbs Conservation Status
Speed demon Most penguins waddle when on land, but the king penguin walks, enabling it to travel at up to 3.5 miles per hour.
LEAST CONCERN
43. The king is a fast walker The king penguin is notable for being the second largest of all penguin species, measuring up to a metre in height. It’s also capable of diving down to 300 metres (984 feet) in ocean waters and remaining there hunting and foraging for a rather lengthy five minutes. Also, rather than waddling on land like all other penguin species, king penguins can walk and run properly due to adaptations in their leg anatomy, with speeds up to 5.6 kilometres (3.5 miles) per hour recorded. King penguins are also known for congregating in some of the Earth’s largest penguin colonies,
with St. Andrew’s Bay on South Georgia frequently witnessing more than 100,000 birds at any one time. On a breeding note, the king penguin is also interesting as it’s one of the earliest capable of reproducing, with individuals able to start the process from the age of three onwards, but most waiting a further three years before mating. The king also has one of the longest breeding cycles, with up to 16 months necessary to raise a chick from egg-laying through to fledging status. Female kings always lay a single egg that weighs approximately 300 grams (10.6 ounces).
During the early explorations of the Antarctic, human explorers ate penguins as a food source. They reportedly had very fatty and oily meat, but today penguin consumption is forbidden.
47. They don’t fear humans Due to their general remoteness from human populations and their activities, penguins seem to be completely unafraid of them, oen being greatly intrigued.
48. Penguins are preyed upon by killer whales Penguins are oen preyed upon by a variety of creatures including leopard seals, sea lions and killer whales. They are also a target for large birds, ferrets and even lizards.
49. The emperor is the fifth heaviest bird on Earth
50. They spend 75% of their lives underwater
44. Penguins create a bubble boost when swimming Penguins can swim at great speeds thanks to an ability to generate a stream of bubbles in their wake. These come from the penguin fluffing its tightly packed feathers, an action that creates a series of micro bubbles to reduce the density of the water immediately surrounding the bird’s plumage. Whenever a penguin travels at high speed, a visible stream of bubbles can be seen surrounding their bodies and trailing off. This technique is oen used when exiting the ocean.
Bubbly wake Penguins create this stream of bubbles that reduces water density around their plumage.
Rather than primarily being a land-dwelling flightless bird, penguins actually spend 75 per cent of their lives underwater, only really coming onto land for long periods to breed.
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© Ardea; Thinkstock; FLPA; Getty; Naturepl.com
Not only is the emperor penguin the heaviest penguin in the world, but it’s also the fih heaviest bird of any species on Earth, weighing in at a rather beefy 45 kilograms (100 pounds).
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