ILLUSTRATED

ENCYCLOPEDIA

OCEANS

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Sea otter An otter that livesin kelp forests. It is keptwarm by its thick fur coat,which traps air and heat. It keeps down the numbers of kelp-eating seaurchins ( 9) by eating them.Floating on its back, it cracks openurchins by striking them with a stoneplaced on its belly.

Sea turtle A marine reptile with a hardshell and large flippers. Turtles come upfor air every few minutes when theyswim. Most species feed on fish, jellyfishand crustaceans but adult green turtlesonly eat plants such as seagrass.

Seal A pinniped with four flippers. Seals have powerful hind flippers. When on land they shu!e along on theirbellies. Seals feed on fish, squid and othersmall sea creatures. They regularly hunt and play in kelp forests.

Sirenians A group of bulky, plant-eatingmarine mammals that live in warm water.Manatees and their river-dwellingrelatives, the dugongs are all sirenians.

Weedy seadragon An Australian relativeof the sea horse that is covered instrange, weed-like projections. These helpit to blend in with the seaweed around it.

Seagrass A type of seaweed that growsin warm, shallow waters. Unlike mostother seaweeds, it has proper roots,meaning it can only grow in sandyregions. Seagrass is the only floweringplant in the sea.

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A manatee feeding in a seagrass meadow

Sea horses wrap their tails around strands of grassto stop themselves drifting away with the currents.

A green turtlefeeding on

seagrass

In some cool, clear, shallow waters,forests of kelp—a kind of seaweed—dominate the underwater landscape.

They teem with animal life. Somecreatures graze on the kelp itself, whilethey, in turn, are prey for larger fish andmammals. In warmer, sandy shallows,fields of flowering seagrass may grow.Like kelp forests, seagrass meadows arehome to many different species. Someanimals migrate to the forests andmeadows to give birth to their young,away from the dangers of the open ocean.

Kelp A type of large seaweed that grows in cool, sunlit waters. Kelp fixes to theseafloor and grows up to the sunlight. Gas-filled pockets help to keep it upright inthe water. Kelp can grow as fast as 50 cm a day, reaching lengths of 30 to 80 m.

Kelpfish A slender fish with green-browncolouring that helps it blend in with thekelp. The kelpfish feeds on small fish andcrustaceans. In the spring, it lays its stickyeggs directly on to the kelp.

Manatee A large, gentle ocean mammalthat lives in warm, shallow waters. It is also known as the “seacow”. It can grow up to 4 m long. It hastwo largeflippers, no rearlimbs and aflattened tail. It has threenails on each flipper, whichhelp it to grasp the seagrassesand water plants that it eats.

! Besides providing food for seacreatures, kelp is used in making paper,textiles, toothpaste and even ice cream.Kelp has been harvested by humans forhundreds of years.

! Seagrass meadows slow down wavesand currents and protect the coast frombeing worn away by the sea.

! Up to 90% of a kelp forest’s growth isswept away during winter storms. Thisclearing is vital as it removes the forest’sdense summer growth, allowing sunlight to reach the forest floor in the spring andstimulate new growth.

Pinnipeds A group of carnivorous marinemammals such as seals and sea lions. They have four flippers that they use topropel themselves through the water.

Sea horse A small fish with a horse-shapedhead and curled tail. Sea horses live insheltered areas such as coral reefs andseagrass meadows. They wrap their tailsaround the plants as an anchor againststrong currents.

Sea lion A pinniped with four flippers andsmall earflaps on the side of its head. Itsstrong front flippers support its body whenon land. In the water, it is an agileswimmer, chasing its prey of fish and squid.

Sea lions are frequent visitors to kelpforests where they hunt.

Algae Plants without true stems, roots andleaves, found in water or moist ground.They include tiny, often single-celled plantsknown as phytoplankton ( 7).

Garibaldi fish A bright orange fish that livesin kelp forests. The male gathers algae thatgrows on the seabed and makes it into anest. He then makes clicking noisesto attract a mate. He willguard his eggs fiercely,chasing o" predatorsmany times his own size. Garibaldi

BlacksmithSea urchinsGiant kelp fishBrittle starSpiny lobsterScorpion fish

KEY1 Kelp2 Sea lion3 Harbour seal4 Sea otter5 Greenling6 Sheepshead

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A weedy seadragon, camouflaged to blend in withweeds and seagrasses.

At night, sea otters wrap strands of kelparound their bodies to stop them

from drifting away with thecurrents as they sleep.

! Covers 12 major subject areas of marine biology

! More than 200 keywords alphabetically listedand clearly explained

! Fact panels with extra information

! More than 80 detailed illustrations

! Comprehensive index

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OOCCEEAANNSSFirst published in 2012 by Orpheus Books Ltd.,

6 Church Green, Witney, Oxfordshire, OX28 4AW, Englandwww.orpheusbooks.com

Copyright ©2012 Orpheus Books Ltd.

Created and produced by Nicholas Harris, Sarah Hartley, Katie Sexton, Ruth Symons and Erica Williams, Orpheus Books Ltd.

Text Ruth Symons

Illustrated by Susanna Addario, Mike Atkinson, Graham Austin, Andrew Beckett,Martin Camm, Robin Carter, Stuart Carter, Jim Channell, Ferruccio Cucchiarini, Peter

Dennis, Fiammetta Dogi, Elisabetta Ferrero, Giuliano Fornari, Andrea Ricciardi di Gaudesi, Ray Grinaway, Gary Hincks, Philip Hood, Ian Jackson,

Mike Lowe, Steve Noon, Nicki Palin, Alessandro Rabatti, Eric Robson, Claudia Saraceni, Peter David Scott, Ivan Stalio, Colin Woolf and David Wright

Consultant Chris Jarvis, Oxford University Museum of Natural History

All rights reserved. No part of this book may be reproduced, stored in a retrievalsystem, or transmitted in any form or by any means, electronic, mechanical,

photocopying, recording or otherwise, without the prior written permission of thecopyright owner.

ISBN 978 1 7418 3762 8

Printed and bound in Singapore

Photograph on page 10: Copyright ©2010 Nick PolingUsed under licence from Shutterstock.com

Photograph on page 15: Copyright ©2010 Eric IsseléeUsed under licence from Shutterstock.com

Photograph on page 20: Copyright ©2010 Kjersti JoergensenUsed under licence from Shutterstock.com

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Each double page contains a brief introduction,explaining the general subject, followed by

key words arranged in alphabetical order. To lookup a specific word, turn to the index at the back ofthis book: this will tell you which page to go to. If youwant to learn more about a subject, take a look at thefactfile, or follow the arrows to read related entries.

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Cnidarians Jelly-like invertebrates withstinging cells. Some, such as coralpolyps ( 17) and sea anemones ( 26), areanchored with their tentacles pointingupwards. Others, such as jellyfish, floatwith their tentacles hanging down in thewater. Cnidarians use sting cells in theirtentacles to paralyse their prey.

Crab A crustacean with a round, flat body,four pairs of legs anda pair of pinchingclaws used for feedingand defence. Most crabslive on the seafloor butsome may live in sandyburrows or even onland. Crabs eat therotting bodies of deadanimals and plants.

Squid A cephalopod with a long, pointedbody, eight arms and two longer tentacles.Squids have an internal shell called a “pen”that protects their inner organs. They havelarge eyes and good eyesight.

Tentacle A flexible limb with no bones orjoints, belonging to some animals,especially invertebrates, such as squid andjellyfish. Tentacles may be used for grippingor feeling objects, or for movement.

Worms A group of long, thin, soft-bodiedcreatures. Some species live in the sea or inthe sand of the seashore.

Crustaceans Arthropods such as crabs,lobsters, krill ( 24) and barnacles ( 26)

that have two pairs of sense receptorscalled antennae on their heads.

Echinoderms Marine invertebrates withspiny skin and skeletons made of chalkycalcium plates. They include starfish ( 27),sea urchins and sea cucumbers.

Gastropods Soft-bodied molluscs, such assnails, slugs and whelks, that move abouton one large foot. Some gastropods havehard, protective shells.

Jellyfish A cnidarian with a bell-shapedbody and tentacles. Jellyfish are morethan 90% water and have no heart, bonesor brain. Some swim by jet propulsion, butmost are carried by the ocean tides andcurrents. Their tentacles have stingingcells with which they paralyse their prey.

Jet propulsionA type of movement

used by some jellyfish andcephalopods. The animal sucks water intothe body sac, then squirts it out. As thewater shoots out backward, the force ofit pushes the animal forward.

Lobster A crustacean with a long body,four pairs of legs and a large pair of claws.Lobsters crawl on the seabed in shallowwater, feeding on starfish, sea urchins,molluscs and crabs. One claw is used forcrushing prey and the other is used forcutting it up.

Molluscs A group of invertebrates withsoft bodies, often protected by hardshells. The main groups of molluscs aregastropods, bivalves and cephalopods.

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Jellyfish

Arthropods Animals, such as insects andcrustaceans, that have jointed legs and anexternal skeleton. This exoskeleton is madeof a light, strong material called chitin,which supports and protects the animal’sbody. As an arthropod grows, it moults itsexoskeleton and grows a new one.

Bivalves Soft-bodied molluscs with twoshells joined by an elastic hinge. Bivalvesinclude scallops, oysters and mussels.

Cephalopods Mollluscs with a large headand a beaked mouth surrounded bytentacles. Cephalopods include squid,octopuses, cuttlefish and nautiluses. They are very intelligent and can changecolour to scare o! predators or blend inwith their surroundings.

Sea slug A soft-bodied sea creature thatmoves on one foot. Because sea slugs arenot protected by a shell, some species arecamouflaged and some are poisonous.

Sea snail A gastropod with a hard shell.Conches, whelks and winkles are all typesof sea snail.

Sea urchin A small, round, spinyechinoderm that feeds on seaweeds andother plants. Its mouth is in its underside,so it crawls on top of things to eat them.

Sponge A type of invertebrate with nomouth, heart, brain or distinct body parts.Sponges live attached to solid surfaces.They feed by passing water through tinypores in their bodies and filtering foodfrom the water.

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Nudibranch A brightly-coloured type ofsea slug. Some nudibranches feed on seaanemones ( 26) and store their stingers asgrowths on their backs as a weapon.

Octopus A cephalopod with a bag-shapedbody, an internal shell and eight arms,used to fight, grab things and move about.The largest octopuses have an arm spanof up to 9 m. Octopuses live on the oceanfloor, feeding on crabs and lobsters. They are thought to be the mostintelligent of all invertebrates.

Scallop A soft-bodied mollusc withtwo shells joined together at a hinge.Scallops move through the water by quickly closing their shells toforce out water and pushthemselves forward.

Sea cucumber A soft-bodiedechinoderm that lives on theocean floor and feeds on deadplant and animal material. It hasfive rows of feet and a mouthsurrounded by tentacles.

Invertebrates are animals that do not have backbones. They come inmany different shapes and sizes.

Many are only found in the sea. Marine invertebrates are a large anddiverse group that includes corals ( 18),sea anemones ( 26), sea urchins, starfish ( 26) and many crustaceans,molluscs and worms. Crustaceans andmolluscs are sometimes groupedtogether and called “shellfish”.

Scallops move through the water by forcing waterfrom their shells to push themselves forward.

An octopuscatching a crab

! The Pacific red octopus has the largestbrain of any invertebrate.

! Most invertebrates have symmetricalbodies, meaning that each half looksexactly the same. The only exception aresponges. Echinoderms are symmetrical fiveways, meaning that their bodies can bedivided into five identical pieces.

! The largest jellyfish, the lion’s mane, hastentacles that are more than 50 m long.

! Some jellyfish, such as the box jellyfish,have a sting powerful enough to kill ahuman within minutes of contact.

A sea urchin

Nudibranch

Lobster

INTRODUCTIONThis explains thegeneral subjectand provides somebasic knowledge.

KEY WORDS AND ENTRIESKey words are arranged alphabeticallyacross each double page. Each entryprovides a short explanation of whatthe key word means.

PAGE NUMBERPage numbersare easy to findat the side ofthe page.

FACTFILEThe factfile provides extrainformation on the subject. Factsare presented in easy to read bulletpoints.

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BOLD WORDSThese highlightuseful words thatdo not have theirown entry.

ARROWS These arrows show you where to look up otherwords mentioned in the entry. For example, ( 26) tells you to go forward to page 26 and ( 6) tells you to turn back to page 6.

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Abyssal plain A flat region of ocean floorlying between 4000 and 6000 m deep. Itis covered by a thick layer of mud calledooze. The animals that live here must liftthemselves out of the ooze, burrow insideit, or find a way of slithering across it.

Abyssal zone The layer of water thatextends from 4000 m down to the oceanfloor. Only a few animals live in this zone.

The ocean is the body of salt waterthat covers about 71% of the Earth’ssurface. There are two main ocean

habitats: the water itself, or pelagichabitat, and the ocean floor, called thebenthic habitat. Both are subdivided intoseveral zones, according to the amount ofsunlight that reaches down through thewater. Most life is concentrated in theupper 200 m where tiny plants andanimals congregate, providing a richsource of food. But some animals manageto survive in the dark, near-freezingwaters in the depths of the ocean.

Bathypelagic zone The layer ofwater between 1000 and 4000 mdeep. To blend in with theirenvironment and so avoidpredators, most creatures inthis zone are dark brown,purple or grey in colour.

Benthic zone The ocean floor. It may be bare rock, coral or a thicklayer of mud.

Black smoker A dark, rocky “chimney”,found along mid-oceanic ridges. Thesechimneys form above cracks in the seabedthrough which hot, sulphur-rich waterspurts out. A number of creatures flourishin the waters near the vent. They eatbacteria that feeds on the sulphur-richwaters, or other bacteria-eating animals.The most amazing of these creatures arethree-metre-long tube worms.

Continental shelf The part of a continentallandmass that lies under ocean waters, nodeeper than 200 m below the surface.

Continental slope The steep part of thecontinental shelf that plunges downtowards the abyssal plain. A constant“rain” of decomposed material from thesurface settles on the slope to form a soft,muddy ooze.

Deep sea trench A very deep valley in theseabed, plunging to depths of 6000 to11,000 m. Trenches are formed when thehuge plates that make up the Earth’s crustpush together, forcing one to slidebeneath the other.

Epipelagic zone The sunlit top 200 m ofocean water. In these waters, there isenough light for plants to make food viaphotosynthesis. The richest variety of lifein the oceans occurs in this zone.

Hadal zone The water found in deep seatrenches. The zone is named after Hades,the Greek god of the underworld.Incredibly, some animals have been foundto live at these depths. They can survivethe great pressure because their bodieshave no air spaces inside them.

Littoral zone The seashore, the part of thesea closest to the land.

Mesopelagic zone The layer of oceanwater that lies between 200 and 1000 mdeep. It is sometimes known as the“twilight zone”.

Phytoplankton Microscopic plants thatfloat in the ocean currents. Phytoplanktonuse sunlight and nutrients dissolved inocean water to make food byphotosynthesis. They comprise most ofthe plant material found in the oceans.

Zooplankton The tiny animals that feedon phytoplankton. These include thelarvae (young) of fish, as well as tinyrelatives of crabs and shrimps calledcopepods. They provide food for a rangeof ocean animals.

OOCCEEAANNZZOONNEESS

Black smokers and the community ofanimals that live near them.

Phytoplankton (left), andthe zooplankton (below)

that feed on them.

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Mid-oceanic ridge A long mountain rangerunning along the ocean floor. It is formedwhere lava erupts between the edges oftwo plates that make up the Earth’s crust.

Pelagic zone The area of open waterbeyond the seashore. It includes theentire ocean except for the ocean floor.

Plankton Tiny plants, known asphytoplankton, and animals, known aszooplankton, that float or swim in thesurface waters of the ocean.

Photosynthesis The process by whichgreen plants use sunlight as an energysource to turn carbon dioxide and waterinto the sugars they need for food.Photosynthesis in the ocean can occuronly in clear, shallow waters.

1 Black smoker2 Tube worms3 Squat lobster

4 Giant clams5 Eelpout6 Brotulid

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Cnidarians Jelly-like invertebrates withstinging cells. Some, such as coral polyps ( 17) and sea anemones ( 26), areanchored with their tentacles pointingupwards. Others, such as jellyfish, floatwith their tentacles hanging down in thewater. Cnidarians use sting cells in theirtentacles to paralyse their prey.

Crab A crustacean with a round, flat body,four pairs of legs anda pair of pinchingclaws used for feedingand defence. Most crabslive on the seafloor butsome may live in sandyburrows or even onland. Crabs eat therotting bodies of deadanimals and plants.

Squid A cephalopod with a long, pointedbody, eight arms and two longer tentacles.Squids have an internal shell called a “pen”that protects their inner organs. They havelarge eyes and good eyesight.

Tentacle A flexible limb with no bones orjoints, belonging to some animals,especially invertebrates, such as squid andjellyfish. Tentacles may be used for grippingor feeling objects, or for movement.

Worms A group of long, thin, soft-bodiedcreatures. Some species live in the sea orin the sand of the seashore.

Crustaceans Arthropods such as crabs,lobsters, krill ( 24) and barnacles ( 26)

that have two pairs of sense receptorscalled antennae on their heads.

Echinoderms Marine invertebrates withspiny skin and skeletons made of chalkycalcium plates. They include starfish ( 27),sea urchins and sea cucumbers.

Gastropods Soft-bodied molluscs, such assnails, slugs and whelks, that move abouton one large foot. Some gastropods havehard, protective shells.

Jellyfish A cnidarian with a bell-shapedbody and tentacles. Jellyfish are morethan 90% water and have no heart, bonesor brain. Some swim by jet propulsion, butmost are carried by the ocean tides andcurrents. Their tentacles have stingingcells with which they paralyse their prey.

Jet propulsionA type of movement

used by some jellyfish andcephalopods. The animal sucks water intothe body sac, then squirts it out. As thewater shoots out backward, the force ofit pushes the animal forward.

Lobster A crustacean with a long body,four pairs of legs and a large pair of claws.Lobsters crawl on the seabed in shallowwater, feeding on starfish, sea urchins,molluscs and crabs. One claw is used forcrushing prey and the other is used forcutting it up.

Molluscs A group of invertebrates withsoft bodies, often protected by hardshells. The main groups of molluscs aregastropods, bivalves and cephalopods.

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Jellyfish

Arthropods Animals, such as insects andcrustaceans, that have jointed legs and anexternal skeleton. This exoskeleton is madeof a light, strong material called chitin,which supports and protects the animal’sbody. As an arthropod grows, it moults itsexoskeleton and grows a new one.

Bivalves Soft-bodied molluscs with twoshells joined by an elastic hinge. Bivalvesinclude scallops, oysters and mussels.

Cephalopods Mollluscs with a large headand a beaked mouth surrounded bytentacles. Cephalopods include squid,octopuses, cuttlefish and nautiluses. They are very intelligent and can changecolour to scare o! predators or blend inwith their surroundings.

Sea slug A soft-bodied sea creature thatmoves on one foot. Because sea slugs arenot protected by a shell, some species arecamouflaged and some are poisonous.

Sea snail A gastropod with a hard shell.Conches, whelks and winkles are all typesof sea snail.

Sea urchin A small, round, spinyechinoderm that feeds on seaweeds andother plants. Its mouth is in its underside,so it crawls on top of things to eat them.

Sponge A type of invertebrate with nomouth, heart, brain or distinct body parts.Sponges live attached to solid surfaces.They feed by passing water through tinypores in their bodies and filtering foodfrom the water.

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Nudibranch A brightly-coloured type ofsea slug. Some nudibranches feed on seaanemones ( 26) and store their stingers asgrowths on their backs as a weapon.

Octopus A cephalopod with a bag-shapedbody, an internal shell and eight arms,used to fight, grab things and move about.The largest octopuses have an arm spanof up to 9 m. Octopuses live on the oceanfloor, feeding on crabs and lobsters. They are thought to be the mostintelligent of all invertebrates.

Scallop A soft-bodied mollusc withtwo shells joined together at a hinge.Scallops move through the water byquickly closing their shells to force outwater and push themselves forward.

Sea cucumber A soft-bodiedechinoderm that lives on theocean floor. It filters the sandybottom for dead plant andanimal material. It has five rows of feet and a mouth surrounded by tentacles.

Invertebrates are animals that do not have backbones. They come inmany different shapes and sizes.

Many are only found in the sea. Marine invertebrates are a large anddiverse group that includes corals ( 18),sea anemones ( 26), sea urchins, starfish ( 26) and many crustaceans,molluscs and worms. Crustaceans andmolluscs are sometimes groupedtogether and called “shellfish”.

Scallops move through the water by forcing waterfrom their shells to push themselves forward.

An octopuscatching a crab

! The octopus has the largest brain of any invertebrate.

! Most invertebrates have symmetricalbodies, meaning that each half looksexactly the same. The only exception aresponges. Echinoderms are symmetrical fiveways, meaning that their bodies can bedivided into five identical pieces.

! The largest jellyfish, the lion’s mane, hastentacles that are more than 50 m long.

! Some jellyfish, such as the box jellyfish,have a sting powerful enough to kill ahuman within minutes of contact.

A sea urchin

Nudibranch

Lobster

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Pectoral fin The fin located on each side ofa fish’s body, used to help the fish steer.

Scales Tiny, layered plates that cover the bodies of many bony fish. Most fishhave scales that overlap eachother to keepwater out and to protect the fish’s body.

School A group of fish or marine mammals,such as dolphins, swimming as a group in

the same direction.

Barbels Whisker-like feelers near themouths of fish, rays and some sharks. They contain taste sensors that help fish to find food in dark or murky water.

Blowfish A medium-sized fish that caninflate its body to more than twice its sizeby swallowing water. This causes sharp,poisonous spines to stick out all over itsbody, scaring o! any predators. It is alsosometimes called a porcupine fish.

Bony fish A group of fish with skeletonsmade of bone. Their bodies are mostlycovered with overlapping scales and theyhave swim bladders to keep them afloat.

Shoal A number of fish that stay togetheras a social group. Shoaling means that fishhave a better chance of survival if they areattacked by predators, and a betterchance of finding a mate.

Stonefish A mottled red fish withvenomous spines down its back. It lives onthe seabed in tropical waters, where it isperfectly camouflaged. Its spines stick upwhen it is threatened and can inject avenom that is fatal even to humans.

Swim bladder An internal organ filled withair that helps fish stay at a certain depth.Swim bladders enable fish to stay buoyantwithout needing toswim. They also help fishsense sound vibrations inthe surrounding water.

Gills The breathing organs of fish, thatextract oxygen from the water. Fish drawwater, which contains oxygen, into theirmouths. When they pump it out throughslits in the side of their head, it passesover the gills and tiny blood vesselsextract the oxygen. Bony fish usually havea protective flap over their gills.

Jawless fish Long, tube-like fish that haveno jaws. They have existed for around 400million years, but the lamprey and hagfishare the only species still alive today.

Fish are vertebrates (animals withbackbones) that live in water all ofthe time. They breathe using gills.

Fish move by flexing muscles along theirbodies in a wave-like motion. Many fishhave a streamlined body shape, with fins,a tail and a coat of overlapping scales.There are two main types of fish: thecartilaginous fish, including sharks andtheir relatives ( 12); and bony fish.

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Flying fish glide above thesurface using their winglike fins.

! Most bony fish have good eyesight and can see in colour. Their eyes are on the sides of their heads, giving them a wide field of vision.

! Bright colours in fish are often a warningto predators that they are poisonous.

! Most fish lay vast numbers of eggs atonce, which they leave to hatch out on their own. A few kinds of fish, such assharks ( 12), carry their eggs inside theirbodies and give birth to live young.

! Fish were the first vertebrates to evolve,millions of years ago. One of the oldesttypes alive today is the coelacanth, fossilsof which date back 90 million years.Coelacanths are the closest link betweenfish and the first amphibians, which movedfrom the water to the land about 375million years ago.

! Around onequarter of allfish species spendtheir wholelife shoaling.

A swordfishThe colourful reed stonefish is one of thedeadliest fish known.

Fins The broad, flat surfaces projectingfrom the body of marine animals such asfish. They are used for steering and balance.

Flatfish A group of bottom-living fish,including flounder and sole. They have botheyes on one side of their flat bodies, so thatthey can spot predators or prey abovethem in the water. They are camouflaged toblend in with the sandy ocean floor.

Flying fish A fish with large pectoral fins likewings. These allow it to swim fast and leapfrom the water to escape from predators.

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Swordfish A large predatory fishwith a distinctive long, flat, sword-likesnout. Swordfish have long, streamlinedbodies up to 4.5 m long. They hunt atnight near the ocean surface, using theirsnouts to stun prey before eating it. They swim at great speed, sometimesleaping out of the water and brieflytravelling through the air at speeds of up to 95 km/h.

Vertebrates Animals with a backbone.Fish are the largest and most diverse

group of vertebrates.

Lionfish A striped, tropical fish, armedwith venomous spines on its back. Its bright markings warn other animalsthat it is poisonous.

To breathe, fish opentheir mouths,

and take in water that

contains oxygen.

As the water passesout over the gills,tiny blood vessels

extract the oxygen.

A lionfish

ANATOMY OF A FISH

European eel

Schooling fish all swim in the samedirection as a group.

Blowfish cansuddenly inflatetheir spinybodies to scareoff predators.

Eye Dorsalfin

Mouth

Gillcover

Caudalfin

Pectoralfin

Cartilaginous fish A group of fishincluding sharks and rays whose skeletonscontain no bone—only a flexible, fibrousmaterial called cartilage. Cartilaginous fishalso have no swim bladder organs to helpthem to stay afloat. They must thereforeswim continuously to stop themselvesfrom sinking to the bottom of the ocean.

Caudal fin The tail fin of a fish used tomove it through the water.

Dorsal fin A fin on the back side of fish,sharks, whales and dolphins. It helps keepthe animal upright while swimming.

Eel A long, ribbon or snake-like fishwithout scales. Eels have long bodies with narrow dorsal fins that do not stickout from their bodies like other fish. They live in the world’s oceans and rivers. Their young are called elvers.

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The hammerhead shark. Its eyes andnostrils are found on either side of its

oddly-shaped head.

Sharks and rays are both kinds ofcartilaginous fish ( 10). Sharkstypically have rows of large, sharp

teeth and feed on fish and squid, butsome species also eat larger prey. Sharks rely on their sense of smell andtheir ability to detect movement in thewater to hunt their prey. Despite theirreputation, only the largest predatorysharks are dangerous to humans. Rays are fish with flat bodies and oftenlong, narrow tails. They have large, wing-like fins that they flap as they swim.

Sharks’ skin is covered with tooth-like scales thatmake their skin rough to touch.

Basking shark

The manta ray—the largest member

of the ray family.

Angel shark A 1.5 m long shark with a wide,flat kite-shaped head. It burrows into thesand on the ocean floor and wait to takesits prey by surprise.

Basking shark A large shark that swims intemperate surface waters. It swims with itsmouth wide open to filter plankton ( 7)

from the water. It can measureup to 12 m. It is docile and

harmless to large fishor humans.

Electric ray A type of ray that gives outelectric shocks. It does this to paralyseprey or to ward o! predators. It lives inwarm waters, and grows up to 2.5 m long.

Frilled shark A rare, deepwater shark withfrilled gills. With its two-metre-long,slender, brown body it looks like an eel.

Goblin shark A rare bottom-dwellingshark best known for its long,

dagger-like snout and protruding,beak-like jaws. It can grow to

3.5 m long.

Great white shark A six-metre-long shark with a grey back and

white belly. It prefers cool coastalwaters, but has been known to

frequent tropical waters. The greatwhite shark mainly feeds on seals and

porpoises but has been known to attackhumans. It is one of the most dangerousspecies to bathers.

Manta ray The largest of the rays, growing up to 7.6 m across. Its namemeans “mantle” in Spanish and refers to its cloak-like appearance. It is also calledthe “devil fish” after its two fins, whichlook like horns. It feeds on tiny creatures,which it filters from the water withits sieve-like gills.

Mermaid’s purse A case surrounding theeggs of some sharks and skates, usuallydeposited on the ocean floor. Other sharksgive birth to live young.

Milk shark A one-metre-long shark thatswims in tropical waters, feeding on smallfish and crustaceans. It has also been found in rivers and tidal streams.

Nurse shark A shark that lives just abovethe seabed in tropical waters and grows upto 2.5 m long. It feeds at night by suckingfood from the sea floor with its soft mouth.

Hammerhead shark A family of sharks thatare distinguished by their hammer-shapedheads, with eyes at each end. This unusualdesign allows them to observe prey asquickly as possible. Most species feed onfish, squid or crustaceans, but largerspecies can be dangerous to humans.

Mako shark The fastest shark in the world,swimming in bursts of up to 50 km/h. It hasa powerful, streamlined body, with indigo-blue colouring and grows up to 4 m long.

Reef shark One of a group ofsharks commonly found near coralreefs. They are all fast andgenerally no more than 3 mlong. They include:white-tip reef sharks;black-tip reef sharks;Caribbean reefsharks; silvertipreef sharks.

Saw shark A sharkdistinguished by itslong snout, lined withsharp teeth. It lives just above the seabed,using its snout to slash at its prey of fishand squid. It grows up to 1.5 m long.

Skates A group of flat, cartilaginous fishthat are relatives of rays. Like rays theyhave wide wings and a long tail, but unlikerays they also have long snouts.

Stingray A family of rays with spines intheir tails that can inject a painful poison.This sting is painful to humans, but it isdeadly to other fish. The stingray livesmostly in shallow, tropical waters.

Thresher shark A shark that rounds up fishby slapping its long upper tail fin againstthe ocean surface. Its tail can also be usedto stun its prey. The thresher shark’s tailcan be the same length as its4.5 m long body.

Whale shark A huge, brown shark withwhite spots across its back. It lives intropical waters. The whale shark is thelargest fish in the world, growing up to 15

m long. It has teeth, but these aretiny and useless. It feeds only

on plankton, krill or smallfish, which it filters from

the water using a partof its gills.

Whale shark

FF AA CC TT FF II LL EE! There are more than 350 di!erent kindsof sharks in the world’s oceans.

! If a shark loses a tooth during feeding, anew one comes forward to take its place.

! Sharks have a keen sense of smell. They are able todetect a singledrop of blood inone million dropsof water.

! About 50 to70 shark attacksare reported everyyear. Of these, lessthan four attackseach year prove tobe fatal.

Blue shark A four-metre-long shark with adeep blue back and a white belly. It lives inthe open ocean where it hunts fish.

Bull shark A large, aggressive shark thatgrows up to 3.5 m long. It is usually foundalong warm coasts but is also known toswim up rivers. It is one of the mostdangerous species to humans.

Chimaeras A group of cartilaginous fishrelated to sharks and rays. They have longbodies and tails and large eyes.

Cookiecutter shark A 50 cm-long sharkwith a slender brown body and a shortsnout. It feeds by using its razor-sharpteeth to cut a round chunk of flesh from itsprey, such as tuna, dolphins and whales.

Dogfish A family of small sharks with twodorsal fins. They feed on fish and squid.

Great white shark

Tiger shark A five-metre-long shark with dark, tiger-likestripes. It hunts in tropicaloceans near coral reefs. It eatsalmost anything at the water’ssurface and can be dangerous to humans.

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Stingray

Diver (to scale)

Mermaid’s purse

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Spy-hopping When a whale pokes itshead above the water to look around it.This may be to search for prey or simplyout of curiosity.

Toothed whales A group of cetaceans,including sperm whales and dolphins,that all have teeth. Toothed whales arealso known as odontoceti.

Bottlenose whale A long, slim whale withits dorsal fin set far back and a pointedmouth like a beak. Males have two tusk-liketeeth, probably used to fight over mates.

Bowhead whale A large, dark,whale found in coldoceans. It feeds onzooplankton ( 7).

Breaching When a whale or dolphinleaps out of the water. This may be in orderto take in air while swimming fast, tocommunicate with other whales, to knockparasites from its skin, or just to have fun.

Cetaceans Carnivorous mammals that livepermanently in the water. Whales, dolphinsand porpoises are all cetaceans.

Echolocation A way of locating solidobjects by emitting high-pitched soundsand picking up their echoes. Dolphins and

whales use echolocation to hunt inlow-visibility conditions.

Killer whale The largest member of thedolphin family, found in all oceans of theworld. The killer whale, or orca, hasdistinctive black and white colouring andgrows up to 8 m long. It feeds on fish,penguins, seals, sea lions, dolphins andeven whales, depending on where it lives.

Lobtailing When a whale or dolphin slapsthe water’s surface with its tail. This can beheard underwater for hundreds of metres.It could be a means of communicating withother whales or of frightening prey.

Logging The resting behaviour of somewhales, during which they float at

the surface of the waterwith their backs anddorsal fins exposed

to the air.

Whales and dolphins are mammalsthat live permanently in thewater. Like other mammals,

they must breathe air. Whales have long,streamlined bodies. Some feed on tinyzooplankton ( 7), filtering their food fromthe seawater. Others have teeth and feedon fish or squid. Dolphins are smaller thanwhales and all have teeth. They areintelligent and playful animals. Some willswim beside ships, riding the wavesploughed by the front of the boat, anactivity called bow riding.

Right whales A type of slow-movingbaleen whale, often found near the shore.It contains more fat than other whales,which once made it an ideal target forhunters. Its name refers to the fact that itwas the “right” type of whale to hunt.

River dolphins A type of small dolphinfound in rivers in South America and Asia.They have distinctive, long snouts.

Rorquals A type of baleen whale thatincludes the blue whale. Rorquals areslender and fast, with distinctive grooveson their lower jaws and undersides.

Sperm whale A large, toothed whale thatcan grow up to 20 m long. It can can diveto depths of up to 3 km, in search of giantsquid ( 22). It can hold its breath for morethan an hour while diving.

Spouting When a whale comes to thesurface to breathe, pushing air from itslungs out through its blowhole. The warmbreath condenses in the cool air andappears as a tall spout of spray.

FF AA CC TT FF II LL EEBaleen whales A group of animals thatfeed by taking in mouthfuls of water andfiltering tiny sea creatures such aszooplankton ( 7) through plates in theirmouths. They are also known as mysticeti.

Baleen Horny plates fringed with fibres,found in the mouths of some whales. These plates strain food from seawater.

Blowhole A whale or dolphin’s nostril ontop of its head, through which it breathes.

Blue whale The largest animal on Earth,growing up to 30 m or more in length. It lives in cold waters and feeds on vast

amounts of krill.

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! Whales can make di!erent sounds toexpress anger, sadness and surprise. There is evidence that they sing tocommunicate with one another.

! Groups of whales often share duties,such as looking after their young. When amother sperm whale dives in search offood, she leaves her baby with anotherfemale to look after it until she returns.

! Since the 17th century, whales have beenhunted on a large scale for meat and oil.Whale hunting, or whaling, was banned inmost countries in the 20th century, but somany large whales were killed in the yearsbefore this that many species, such as theblue whale and Northern right whale arestill endangered.

To feed, a baleen whale takes in a vast mouthful ofwater, full of tiny sea creatures.

As it forces water out again the creatures are caughtin the baleen and swallowed.

Pilot whale A large, sleek, black dolphinwith a bulging forehead. Pilot whales livein cool, deep oceans, feeding on squid andfish. They are known for their distinctiveupward-curving mouths or “smiles”.

Pod A group of dolphins swimmingtogether. Males in this group are called“bulls”, females “cows” and their young“calves”. Pods may stay together for life.

Porpoises A group of small, toothed, cetaceans, related to whales anddolphins. Porpoises are stockier thandolphins and have more rounded snouts.Most are shy animals that stay beneaththe surface of the water as much aspossible. This means that they are rarelyseen by humans.

Dolphins breaching

This human diver showsthe size of a 16 m-longhumpback whale.

A dusky dolphin herds fish together by slapping itsfins on the water to scare them.

Harbour porpoise

A killer whale breaching

Humpback whale A large baleen whalethat can grow to 15 m long. Humpbackwhales often leap backwards out of thewater. They feed on krill and small fishwhich they filter from the water. They areknown for their distinctive “songs”.

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Oystercatcher A black and white waderwith a red beak and legs. It lives on theshore, using its long beak to probe throughsand and tidal pools in search of worms,crustaceans and shellfish such as oysters.

Pelican A large seabird with a prominentthroat pouch. This is used to scoop up fishfrom the water like a fishing net. Once thepelican has drained the water from itspouch, it swallows its prey.

Pu!n A small black and white seabirdwith orange feet and an orange and bluestriped beak. Pu"ns use their wings topush them through the water in pursuit offish. They can hold up to 12 small fish intheir beaks, which they carry back to feedtheir chicks. Pu"ns nest underground,sometimes in abandoned rabbit burrows.

Pursuit diving The style of hunting inwhich seabirds swim after their preyunderwater. Some pursuit divers, such asauks, use their wings to push themselvesthrough the water, while others,such as grebes and loons, usetheir feet as paddles.

SSEEAABBIIRRDDSS

Tropicbird A large, white seabird withlong, pointed tail feathers. Tropicbirdsbreed on islands far out in the ocean. They hover above the water beforeplunging down to catch their prey.

Waders Any of the long-legged birds such as oystercatchers and curlews that wade out into shallow water to feed. Wading birds are commonly found on the seashore.

Webbed feet Feet shaped like paddleswith a flap of skin between each toe.Webbed feet help aquaticanimals and birds to swimmore easily.

A great skua attacks a storm petrel in order tosteal its catch.

Seabirds live near the ocean, feeding on fish, squid, worms orcrustaceans. Some kinds dive into

the water from the air, or from highrocks. Others skim over the surface,scooping up food. Some, such aspenguins ( 24), can pursue their prey byswimming through the water. Mostseabirds have waterproof feathers andrough, webbed feet to help them paddleor snatch up slippery fish. Many seabirdsgather in large colonies to lay their eggs,often laying just one egg.

An albatross scoops a squidfrom the ocean

Skua A grey or brown seabird that lives inpolar regions. Skua mainly feed on fish butalso steal food from other individuals andsnatch eggs and chicks from the nests ofother birds. Some larger species, such asthe great skua can even kill and eat otheradult birds.

Tern A grey or white seabird. Terns, closely related to gulls, live on

coastlines, feeding on crustaceans andsmall fish which they catch by

diving from high in the air.

Frigatebird

Great skua

Storm petrel

Petrel A small brown or grey seabird.Diving petrels use their wings to powerthem through the water after fish, whilestorm petrels snatch fish and planktonfrom the surface waters with their beaks.

Plunge diving The type of hunting, used bybirds such as gannets and boobies, wherethe birds use airborne momentum topower through the water after their prey.

Booby A large black and white seabird thatdives for its prey from the air. Boobies livein tropical areas, feeding on fish and squid.Some species are distinguished by theircoloured feet and bills.

Colony A large group of birds nesting orroosting (resting) together. About 95% ofseabirds are colonial, often returning to the same place every year to nest. Some species nest on the ground, whileothers nest on cli!sides or in burrows.

Cormorant A black, long-necked seabird,sometimes called a shag. Cormorants livealong coastlines. They dive for fish from theocean surface, using their feet to swimafter their prey.

Frigatebird A large, black and whiteseabird. In mating season, the male’sthroat pouch becomes red and inflates inorder to attract a mate. Frigatebirdssometimes steal food from other birds bybiting their tails and forcing them torelease their catch, which they then eat.

Gannet A black and white seabird. Gannetsplunge dive from 30 m high, poweringthrough the water after their prey.

Gull A large, white or grey bird that lives incoastal areas. Gulls feed on crabs and fishfrom shallow waters but also scavenge andsteal food from other birds. There are morethan 50 types of gull, including the herringgull and the black-headed gull.

Pelican

Albatross A large, white seabird that cango for months without touching land. Albatrosses scoop up squid, octopusesand fish from the ocean’s surface. Thewandering albatross and royal albatrosshave a wingspan of 3.5 m—the largest ofany living bird.

Auk A black and white diving bird thatlives in the northern oceans. Auks are verysimilar to penguins in their body shapeand their ability to swim well underwaterbut, unlike penguins, they can fly. Thereare several species of auk, includingguillemots, pu"ns, auklets and murrelets.

! Seabirds often live much longer thanland birds, reaching ages of 20 to 60 years.

! Seabirds take in large amounts of saltwhen they drink and feed. To removeexcess salt, they have a special gland abovetheir eyes to remove and release excesssaltwater. This runs down their beaks anddrips away.

! Some cli!-nesting seabirds, such asguillemots, lay pointed, pear-shaped eggs.These are less likely to roll o! the rock edgethan normal, rounded eggs.

Red-tailedtropicbird

A group of North-Atlantic puffins

A brown booby dives into the ocean after its prey.

Barracuda A two-metre-long fish thathunts around coral reefs. It has a fierceappearance, with sharp teeth juttingforwards from its lower jaws. It hunts ingroups known as batteries.

Barrier reef A coral reef that is separatedfrom the shore by a pool of seawatercalled a lagoon. Barrier reefs lie fartherfrom the shore than fringing reefs.

Butterflyfish A small, brightly-colouredfish, often with eye-like markings on itstail. These encourage predators to attackthe wrong end of the fish’s body, giving ita chance to escape. Butterflyfish feed onsmall crustaceans and coral polyps.

Clownfish A small orange and white fishthat lives inside the poisonous tentacles ofsea anemones ( 26). The fish is protectedfrom the poison by a layer of mucus, butits enemies would be stung to death.

Coral A hard substance produced by theskeletons of tiny animals called polyps.Di!erent kinds of polyps produce di!erentshapes of coral. Some are shaped likebranching plants, others are flat like a fan,long and thin like pipes or rounded likehuman brains. Only the living surface ofthe coral is coloured by the presence ofalgae ( 20). The layers of polypskeletons underneath are white.

Crown-of-thorns starfish A large, brightly-coloured starfish ( 21) with at least 12arms covered in long, venomous spines. It feeds on coral polyps. This can threatenthe survival of the reef.

Fringing reef A coral reef that grows inshallow water along a rocky coastline.

Moray eel A three-metre-long eel thathides in coral crevices, waiting to burstout on its prey, a fish or anoctopus.

Parrotfish A brightly coloured fish with ahard, beaked mouth. It scrapes algae ( 20)

from the reef, biting o! chunks of coral asit does so. Its throat contains bony platesthat grind the coral into sand and help todigest the algae.

Polyp A tiny animal made up of a stomach,mouth and tentacles. Its soft body isprotected by a hollow, cup-like skeleton.When the polyp dies, this forms the hard,dead part of coral and anew polyp grows inthe remains.

Atoll A ring of coral islands. An atoll forms where a coral reef has grownaround a volcanic island. When thevolcano stops erupting, it will sink into theocean floor. As it gradually sinks, the coralreef keeps growing upwards and willeventually be all that shows above water.

CCOORRAALLRREEEEFFSS

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Acoral reef is an underwaterstructure formed from the hardskeletons of tiny animals called

polyps. Coral reefs are found in warm,clear, shallow waters around volcanicislands or rocky coastlines. They teemwith wildlife. Many small creatures feedon plants called algae ( 20) inside thecoral. The coral itself is consumed bysome animals such as parrotfish and thecrown-of-thorns starfish. Predators, suchas sharks, rays and barracudas, prey onthe creatures that feed on algae or coral.

Clownfish shelterin their sea

anemone home.

Coral polyp

Morray eelSea snakeReef sharkSea urchinSea horseSurgeonfishAngelfishTriggerfish

KEY NudibranchCrown-of-thornsstarfishButterflyfishGrouperGiant clamLionfishTube spongeBarracuda

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! The Great Barrier Reef, which runs alongthe northeastern coast of Australia, is theworld’s largest coral reef. It is more than2000 km long along.

! The bright colours and distinctivepatterns of many reef fish are thought tohelp them recognize their own speciesamong the throng of wildlife on the reef.

! Until about 200 years ago, coral was thought to be a plant and not a creature.

! Many coral reefs around the worldare under threat. Polluted waters,

rising sea temperatures, damage bytourists hunting for souvenirs and

dredging for shipping lanes all destroycoral that has been growing for

millions of years.

Sea snake A snake that spends its life inthe oceans. Sea snakes live in warm,tropical waters, hunting fish and eels.They breathe air at the surface and haveflattened tails to help them swim. Thereare around 60 species of sea snake, all ofwhich are venomous. Many species havestripy skin, to help them camouflage withthe dappled light and shade of the sea.

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Sea otter An otter that livesin kelp forests. It is keptwarm by its thick fur coat,which traps air and heat. It keeps down the numbers of kelp-eating seaurchins ( 9) by eating them.Floating on its back, it cracks openurchins by striking them with a stoneplaced on its belly.

Sea turtle A marine reptile with a hardshell and large flippers. Turtles come upfor air every few minutes when theyswim. Most species feed on fish, jellyfishand crustaceans but adult green turtlesonly eat plants such as seagrass.

Seal A pinniped with four flippers. Seals have powerful hind flippers. When on land they shu#e along on theirbellies. Seals feed on fish, squid and othersmall sea creatures. They regularly hunt and play in kelp forests.

Sirenians A group of bulky, plant-eatingmarine mammals that live in warm water.Manatees and their river-dwellingrelatives, the dugongs are all sirenians.

Weedy seadragon An Australian relativeof the sea horse that is covered instrange, weed-like projections. These helpit to blend in with the seaweed around it.

Seagrass A type of seaweed that growsin warm, shallow waters. Unlike mostother seaweeds, it has proper roots,meaning it can only grow in sandyregions. Seagrass is the only floweringplant in the sea.

FFOORREESSTTSS &&MMEEAADDOOWWSS

A manatee feeding in a seagrass meadow

Sea horses wrap their tails around strands of grassto stop themselves drifting away with the currents.

A green turtlefeeding on

seagrass

In some cool, clear, shallow waters,forests of kelp—a kind of seaweed—dominate the underwater landscape.

They teem with animal life. Somecreatures graze on the kelp itself, whilethey, in turn, are prey for larger fish andmammals. In warmer, sandy shallows,fields of flowering seagrass may grow.Like kelp forests, seagrass meadows arehome to many different species. Someanimals migrate to the forests andmeadows to give birth to their young,away from the dangers of the open ocean.

Kelp A type of large seaweed that grows in cool, sunlit waters. Kelp fixes to theseafloor and grows up to the sunlight. Gas-filled pockets help to keep it upright inthe water. Kelp can grow as fast as 50 cm a day, reaching lengths of 30 to 80 m.

Kelpfish A slender fish with green-browncolouring that helps it blend in with thekelp. The kelpfish feeds on small fish andcrustaceans. In the spring, it lays its stickyeggs directly on to the kelp.

Manatee A large, gentle ocean mammalthat lives in warm, shallow waters. It is also known as the “seacow”. It can grow up to 4 m long. It hastwo largeflippers, no rearlimbs and aflattened tail. It has threenails on each flipper, whichhelp it to grasp the seagrassesand water plants that it eats.

! Besides providing food for seacreatures, kelp is used in making paper,textiles, toothpaste and even ice cream.Kelp has been harvested by humans forhundreds of years.

! Seagrass meadows slow down wavesand currents and protect the coast frombeing worn away by the sea.

! Up to 90% of a kelp forest’s growth isswept away during winter storms. Thisclearing is vital as it removes the forest’sdense summer growth, allowing sunlight to reach the forest floor in the spring andstimulate new growth.

Pinnipeds A group of carnivorous marinemammals such as seals and sea lions. They have four flippers that they use topropel themselves through the water.

Sea horse A small fish with a horse-shapedhead and curled tail. Sea horses live insheltered areas such as coral reefs andseagrass meadows. They wrap their tailsaround the plants as an anchor againststrong currents.

Sea lion A pinniped with four flippers andsmall earflaps on the side of its head. Itsstrong front flippers support its body whenon land. In the water, it is an agileswimmer, chasing its prey of fish and squid.

Sea lions are frequent visitors to kelpforests where they hunt.

Algae Plants without true stems, roots andleaves, found in water or moist ground.They include tiny, often single-celled plantsknown as phytoplankton ( 7).

Garibaldi fish A bright orange fish that livesin kelp forests. The male gathers algae thatgrows on the seabed and makes it into anest. He then makes clicking noisesto attract a mate. He willguard his eggs fiercely,chasing o! predatorsmany times his own size. Garibaldi

BlacksmithSea urchinsGiant kelp fishBrittle starSpiny lobsterScorpion fish

KEY1 Kelp2 Sea lion3 Harbour seal4 Sea otter5 Greenling6 Sheepshead

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A weedy seadragon, camouflaged to blend in withweeds and seagrasses.

At night, sea otters wrap strands of kelparound their bodies to stop them

from drifting away with thecurrents as they sleep.

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Gulper eel A two-metre-long eel with agaping mouth and a light on its tail, used to attract prey. The gulper eel can live at depths of up to 3000 m. It has huge jaws and a stretchy stomach thatallows it to swallow animals that arelarger than itself.

More than 200 m deep, it is darkand cold and no plants cangrow. Only a few animals can

survive these conditions. Some migrateto the surface every night to feed. Otherseat dead matter that sinks from above, orprey on each other. Many creatures cancreate their own light. Near the oceanfloor the water is pitch black and thepressure is immense. Animals rely ontouch or smell to detect food. Some ofthe animals that live at the bottom of theocean are attached to the ocean floor andlook more like plants than animals.

Viperfish

Ooze A thick layer of mud and sedimentsthat builds on the ocean floor. It may lie upto 500 m thick in some places. The animalsthat live on the sea floor must either liftthemselves out of the ooze, burrow insideit or find some way of slithering across it.Some animals eat the ooze for the animaland plant remains that it contains.

Rat-tail A common fish, also known as agrenadier, that has a long thin tail andswims above the ocean floor. A specialsensor running down its spine feels themovements of other creatures nearby. It makes a loud drumming noise byvibrating muscles attached to its swimbladder ( 11). This may be a way ofsignalling to others of its kind.

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Anglerfish A fierce-looking deep waterfish. Anglerfish have a long thin dorsal finwith a light at its tip, called a lure. It hangsthis in front of its mouth. When its preylunges at the light, believing it to belongto another tiny animal,the anglerfish closes itsjaws. Some species ofanglerfish haveteeth that lie flatand then spring backaround their prey when it is insidetheir mouths. Most species of liveat depths of around 500 m.

DDEEEEPP SSEEAACCRREEAATTUURREESS

Bioluminescence Natural light created inthe body of a living creature. Many deepwater animals are bioluminescent. They may use light to lure prey, or as asignal to other creatures of the samespecies. They may also flash lights on ando! to confuse an attacker.

Brotulid The world’s deepest-living fish. It is long and thin with a pointed tail. It lives in deep sea trenches ( 6) at depths of up to 8000 m.

Firefly squid A small squid that lives atdepths of 200 to 400 m. It has light-

making parts at the tips of itstentacles, which it can flash toattract small fish. Its whole bodymay light up to attract a mate orconfuse a predator.

Giant squid A type of squid ( 9)

that can grow to at least 13 mlong. Giant squid feed on deep

sea fish. They themselves arepreyed upon by sperm whales ( 15).

Giant squid are thought to live at depthsof between 200 and 1000 m, but

are di"cult to study, sorelatively little is knownabout them.

Sea pen A type of invertebrate ( 8) thatcan live at great depths. A sea pen is notone animal, but is a colony of polyps ( 19).One polyp forms a long stalk, that anchorsthe pen to the sea floor. Other polypsbranch o! and filter food from the water.

Sea spider A fine-legged, spider-likecreature that lives on the ocean floor,feeding on sponges ( 9) and worms. Its long legs allow it to pick its way across the ooze.

Hatchetfish A small, bioluminescent fishthat lives at depths of up to 1500 m. It has a flattened body that makes it hard forpredators to spot in the water. It feeds onother, smaller fish.

Lanternfish A small fish with bioluminescentspots. It spends the day at depths of 300 to1500 m but rises to the surface at night tofeed on zooplankton ( 7).

A giant squid locked in battle with a sperm whale

Angler fish

Vampire squid

Gulper eel

Sea pens

Rat-tail

Tripodfish

Sea anemone

Venus flower basket

Sea spider

Sea pen

Sea cucumber

The skeletons of tiny plankton that have rainedslowly down from surface waters into the ooze.

Vampire squid A small sea creature thatlives at depths of 600 to 900 m. It has aweb of skin that stretches between itseight arms and is covered inlight-emitting spots. It canflash these very quickly toconfuse predators.

Tripodfish A fish that lives on the oceanfloor at depths of up to 5 km. It rests onthe ocean floor on a “tripod” made of itslong, stilt-like fins and tail. Another pair offins is held up in the air to detect themovements of passing prey, whereuponthe tripodfish pushes itself forward tosnatch up its victim.

ViperfishA long, thin fish withfierce jaws and needle-liketeeth. The viperfish lives at depths of 80to 1500 m. It has a special light organ atthe end of a spine on its back, which is

used to lure prey towards its mouth.

! The deeper you go in the ocean, thegreater the weight of water pressurepressing down from above. Below 50 m, thispressure is too great for human divers.

! In 1960, scientists descended 10,911 m intothe Marianas Trench in the Pacific Ocean inthe submersible Trieste. To withstand thepressure, the capsule walls were 13 cm thick.

! Some deep-water animals such as shrimpare dark red. Red light does not reach thedepths at which the shrimp live so they arepractically invisible in the blue-green water.

! Cans, bottles and ship wrecks litter theocean floor. Found on all parts of the oceanfloor, especially beneath shipping lanes, isclinker, burnt coal dumped from steamshipsbetween the 1850s and 1950s.

Featherstar

Sea cucumberHatchetfish

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Penguins Flightless birds, manyspecies of which live on cold, southerncoastlines near Antarctica. Clumsy on land,penguins are swift and graceful in thewater. Their sti!, flipper-like wings pullthem through the water in pursuit of fishand squid. To keep warm they have severallayers of dense feathers, and a thick layer ofblubber. They breed in large colonies onland or on ice.

Walrus

Bearded seal A seal that lives in the ArcticOcean. It is named after the manywhiskers that cover its face.

Beluga whale A five-metre-long whalethat lives in the Arctic. In summer, thisdistinctive white whale feeds on fish andcrustaceans found on the seabed beneaththe pack ice.

Blubber The oily fat found under the skinof many marine animals living in coldocean waters.

Breathing hole A hole in the ice whereseals and penguins come to the water’ssurface to breathe. Polar bears sometimeswait at the surface to grab seals.

Elephant seal A large seal that migrates toAntarctica once a year to breed. The

male has an enormous, trunk-likenose. It makes threatening

roars to drive away rivals.

Harp seal A type of seal that lives in thenorthern Atlantic and Arctic Oceans. It has a grey body, but its young, calledpups, are covered in soft white fur.

Ice fish A semi-transparent fish that livesin Antarctic waters. It is able to survivebecause it has a natural “anti-freeze”

in its blood to stop it freezing in the icy waters.

King penguin The second-largest species of penguin.

It lives in large groups onislands in the Southern Ocean.

An expert diver, it swims insearch of fish and squid to eat.

A polar bear lies in wait for a seal ata breathing hole in the ice sheet.

Krill A small, shrimp-like crustacean. It forms a large part of the diet of manypolar animals. Krill spend their days in theocean depths. Vast numbers of them swimto the surface at night to feed, wherewhales and seabirds feast on them.

Leopard seal A four-metre-long, spottedseal that hunts in the Antarctic Ocean. Its favourite prey is the Adélie penguin, butit also eats fish, birds and even the youngof other seals.

Narwhal A whale native to Arctic waters.Narwhals live in the Arctic all year round,unlike other whales which move south inthe winter. Males have a long, spirallingtusk, which is actually one of their twoteeth and may be used for fighting.Narwhals feed on fish, shrimp and squid.

Polar bear A large Arctic bear witha thick, white, waterproof coat.Underneath its fur, its skin is actuallyblack, which helps trap heat from the sun.Its claws and hairs on the soles of its feetgive it grip on the Arctic ice and it is alsoan expert swimmer. The polar bear feeds

mainly on seals, which it waits for atbreathing holes in the ice.

Adult bears roam the icealone. In winter,

females dig dens inthe snow to protect

them from theextreme cold while they

give birth to their young.

Walrus A large sea mammal with two longtusks and powerful flippers. A layer ofblubber under its skin keeps it warm in thefreezing Arctic water. The walrus is anexcellent swimmer, searching the seabedwith its sensitive whiskers for crabs andshellfish. Males use their tusks as weaponswhen fighting over females.

Emperor penguin The largest type ofpenguin, growing up to 1.2 m tall. It is theonly species of penguin to breed duringthe Antarctic winter. While the femaleshunt, the males look after the eggs,carrying them on their feet to keep themo! the ice. The emperor penguin canremain underwater for up to 15 minutes.

PPOOLLAARRWWAATTEERRSS

A leopard seal in pursuit of an Adélie penguin

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Although they are the coldestplaces on Earth, the oceans at thepoles are home to many creatures.

Much of the Arctic Ocean is covered witha thick layer of floating ice all year round.In summer, when the waters are teemingwith tiny plants and animals, fish, seals,whales and seabirds gather there to huntfor food. Antarctica is a huge landmass,largely covered by a permanent ice cap.There is little food on land, so mostanimals cluster around the coasts wherethe ocean waters are rich with planktonand other food.

Krill

Emperorpenguins

Adélie penguins

Adélie penguin A medium-sizedpenguin with a white ring aroundits eye. Adélie penguins are thefavourite food of the leopard seal.Many of these penguins hesitate at thewater’s edge, none wanting to dive infirst, for fear of this ferocious predator.

Antarctica The continent located at theSouth Pole, surrounded by the AntarcticOcean. It is the coldest place on Earth.

Arctic The area surrounding the NorthPole, including the polar ice cap and theArctic Ocean.

Narwhal

! When standing on ice, penguins’ specialcirculatory systems stop their feet fromfreezing by keeping heat inside the bloodvessels, preventing it from being lostthrough the skin.

! Walrus’ tusks can grow up to 1 m long.

! In the Middle Ages, narwhal tusks werebrought south and traded as unicorn horns.Many Europeans did notrealise what theseobjects really were untiltheir own explorersreached the Arctic in the16th and 17th centuries.

A two-month-old king penguin

SSEEAASSHHOORREEStarfish An invertebrate ( 8) with five legsand a mouth on the underside of its body.Using the suckers on its arms, it can fastenon to a shellfish and prize it open to feedon the fleshy parts inside. If a starfish isattacked, it can lose an arm in order tomake its escape. This will then grow back.

Tidal pool A pool collected between rockswhen the tide goes out. Tidal pools maybecome very warm in hot sunshine orsuddenly flooded at high tide. These arerich in life, including animals such asstarfish, sea anemones and small fish,which could not otherwise survive so farup the shore.

Tide The rise and fall of the sea every 12and a half hours. Tides are caused by thepull of gravity that the Sun and Moonhave on the Earth. Ocean waters on theside of the Earth closest to the Moon (andthe opposite side) bulge outwards,causing a high tide. At the same time, therest of the Earth has a low tide. The Sunmay increase or lessen the Moon’s effect.

Anemone A sea creature that looks like aflower. It is a type of cnidarian ( 8), relatedto jellyfish ( 8) and polyps ( 25). It attachesitself to rocks and uses its tentacles to stingits prey. When in danger, or at low tide, itcan withdraw its tentacles.

Holdfast A claw-shaped foot that anchorsseaweeds to rocks or the seabed.

Limpet A seashore snail with a flattened,conical shell. Limpets firmly attachthemselves to rocks but move aboutduring high tide to look for food.

Low tide zone The area of the seashorethat is almost constantly covered by thesea. It is only exposed during unusually low tides. It is inhabited by creatures thatdepend on the moisture of the sea.

Barnacle An animal with a cone-shapedshell and feathery legs which it uses toscoop food towards its mouth. Barnaclescement themselves to rocks, or other hardobjects such as the bottom of ships, oreven the skin of whales.

Blenny A small fish that lives on rockyshores and is often found in tidal pools.Most species of blenny are green or brown,in order to blend in with their surroundingsand escape detection by predators.

Burrowers Sea creatures, such as wormsand clams, that burrow underground atlow tide to both keep moist and seekprotection from waves or predators.

Hermit crab A type of crab that has no shellof its own but lives in the empty shells ofother animals. Hermit crabs scavenge ondead plant and animal debris.

High tide zone The area of theseashore that is covered by

the sea only at high tide.

Lugworm A burrowing worm that lives ina U-shaped tunnel in the sand of theseashore. It sucks water and food downthe tunnel, then pumps waste back up it.

Mussel A small, black shellfish that livesattached to rocks. Mussels feed on tinyparticles of food found in seawater. When the tide goes out they shut theirshells, trapping water inside them, whichstops them from drying out.

Seaweed A type of algae ( 20) that growsattached to the seafloor. Seaweeds are asource of food for some animals, as wellas a cool, damp shelter for some seashorecreatures when the tide goes out. Greenseaweed grows near the top of the shoreand brown weed near the sea.

Spray zone The area at the top of theseashore, that is splashed by waves athigh tide but only covered by the seaduring storms.

A sea anemone,with its tentacleswithdrawn

The seashore is the place where theland meets the sea. The creaturesthat live on the shore must be able

to survive the changing conditionsbrought on by the tides. They live atdifferent levels, or zones, according to how well they can survive out of water.Shelled animals, which can keepthemselves moist, live higher up theshore. Starfish, worms and others livelower down, where it is wet for more ofthe day. On some shores tidal poolsform between rocks.

An open seaanemone with

tentacles showing

FF AA CC TT FF II LL EEA starfish opening mussels with its feet

! Hermit crabs sometimes go intopartnership with sea anemones. Theanemone lives on the crab’s shell, providingcamouflage and using its tentacles toprotect the crab from predators. In returnthe anemone feeds on the crab’s leftovers.

! Some seashore creatures, such aspiddocks, barnacles and sea urchins, canbore, or drill, into rocks to escape fromtheir predators. They drill through softrock with their hard shells, using a twistingand rocking motion to carve out apassageway.

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2

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4

7

8

9

10

12

11

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5

13

OystercatcherSea urchinBlennyLimpetStarfishPrawnBrittlestarHerring gullBeadlet anemoneCrabMusselsButterfishSea lettuceHermit crab

KEY1 2 3 4 5 6 7 8 9 10 11 12 13 14

26 27

28 29

Grey whale A large species ofwhale that migrates betweenfeeding and breedinggrounds every year. It feeds in Arctic waters insummer, then, in the winter it migrates to warmer waters in Mexico to breed. The whales travel in small groups, taking two or three months to complete the 10,000 km journey.

Green turtle A large seaturtle that migratesaround 2000 km to layits eggs. Every two orthree years green turtlesleave the coast of Braziland travel to their breedinggrounds on Ascension Island inthe middle of the Atlantic Ocean.Each turtle lays about 100 eggs inthe sand, then covers them andreturns to sea.

Short-tailed shearwater A bird that makes a seven-

month migration every year. It spends its summer breeding on

the Australian coast. In April it fliesnorth across the Pacific to feeding

grounds in the Bering Sea. It travels about15,000 km in each direction every year.

Vertical migration The movement ofanimals up and down through di!erentdepths of ocean water. For example, somedeep-sea creatures, such as the lanternfishor hatchetfish ( 12) travel to the upperlayers of the ocean to feed every night,returning to the depths during the day.

Salmon A fish that is born in a river, livesin the oceans, then swims back to thesame river to breed. The journey mayexceed 11,000 km. Salmon are thought tofind their way by recognizing the taste oftheir “home” rivers.

Wandering albatross A largebird that spends nearly all its life

airborne, coming to land on islands onlyto breed. Every other year it returns toan island near Antarctica where it wasborn. Here, couples build a nest and layand hatch a single egg. Many marine animals make long

journeys to breed or to reach richfeeding grounds. This is called

migration. Some animals may fly or swimhuge distances each year. Other animalsonly make the journey every few years orjust once in their lifetime. Animalsnavigate (find their way) by recognizinglandmarks, observing the position of thesun and stars or using scent. Scientiststhink that some routes are passed downfrom one generation to another throughanimal genes. Other animals are thoughtto navigate by sensing the Earth’smagnetic field, though scientists have yetto fully understand this.

Grey whale

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MMIIGGRRAATTIIOONN

Elvers (young eels)

The wandering albatross

Arctic tern A bird that breeds in the Arcticin the northern summer, then migrates tospend the southern summer feeding inthe Antarctic. This is a round journey ofabout 71,000 km.

European eel A freshwater eel thatmigrates across the Atlantic Ocean when it hatches and again, at the end of its life,to lay its eggs and die. The young eels areborn in the Sargasso Sea, east of Florida.They drift back to Europe on oceaniccurrents, then swim up rivers and growinto adults.

Pacific salmon

Arctic tern

Short-tailedshearwater

Pacific salmon

Grey whale

Short-tailedshearwater

Wandering albatross

Green turtle

ATLANTICOCEAN

Arctic tern

Young ofEuropean eel

PACIFICOCEAN

! The Arctic tern’s 71,000 km journey is the longest migration of any animal inthe world.

! The wandering albatross covers thegreatest distances of any bird over thecourse of its life. An albatross can live up to60 years old and travel millions ofkilometres during its lifetime.

! The green turtle is thought to be thefarthest-travelled reptile in the world.

! Migrating animals time their journeyswith incredible precision. Departure datesoften vary by less than two weeks fromyear to year.

Green turtlehatchlings are

picked off by gullsand crabs.

AAabyssal plain 6abyssal zone 6-7albatross

royal 16wandering 16, 28-29

algae 18-19, 20, 27amphibians 11angelfish 18anglerfish 22-23Antarctic Ocean 24-25, 28Antarctica 24-25, 29antennae 8Arctic Ocean 24, 28arthropods 8Ascension Island 28Asia 15Atlantic Ocean 24, 28-29atoll 18auk 16-27auklet 16Australia 19, 29

BBbackbone 8, 10-11bacteria 6baleen 14-15barnacle 8, 26-27barracuda 18bathypelagic zone 6-7bear, polar 24-25benthic zone 6Bering Sea 29bioluminescence 22birds 16-17, 24-25, 28-29bivalves 8black smoker 6blenny 26blowfish 10-11blowhole 14blubber 24-25booby 16bow riding 14Brazil 28

breaching 14breathing hole 24-25brittle star 21, 26brotulid 6, 22burrow 6, 16-17, 23, 26butterfish 26butterfly fish 18

CCcamouflage 9, 10, 19, 20, 27carbon dioxide 7cartilage 10cephalopod 8-9cetaceans 14-15chimaeras 12chitin 8clam

giant 6, 18clams 26clownfish 18cnidarians 8, 26coastline 12, 17, 18coelacanth 11colony 16, 23, 25conch 9continental shelf 6copepod 7coral 6, 8, 18-19coral reef 13, 18-19, 20cormorant 16crab

hermit 26-27crabs 7, 8-9, 16, 25, 26crustaceans 8, 13, 17, 18,

20-21, 24-25curlew 17currents 20-21, 28cuttlefish 8

DDdeep sea trench 6, 22dogfish 12dolphin

dusky 14river 15

dolphins 10-12, 14-15dugong 21EE

echinoderms 899echolocation 14eel

European 11, 28gulper 22-23moray 18

eels 10, 19, 29eelpout 6elver 10, 29endangered 15epipelagic zone 6-7Europe 28exoskeleton 8

FFfeather 16feather star 23fin 10, 13, 23

caudal 10dorsal 10, 12, 14, 22pectoral 10-11

fish 10-14, 16-17, 19, 20-22, 24-27, 29

bony 10cartilaginous 10, 12

flatfish 10Florida 28flounder 10flying fish 10-11frigatebird 16-17

GGgannet 16garibaldi 20-21gastropods 8giant kelp fish 21gills 10, 13Great Barrier Reef 19grebe 17greenling 21grenadier 23grouper 18guillemot 16-17gull

black-headed 16herring 16, 26

gulls 16-17, 29

HHII

habitat 6benthic 6pelagic 6

hadal zone 6-7hagfish 10hatchetfish 22, 29high tide zone 26holdfast 26hunting 15ice cap 24invertebrates 8-9, 23, 27

JJKKjawless fish 10jellyfish

box 9lion’s mane 9

jellyfish 8, 21, 26jet propulsion 8kelp 20-21kelpfish 20krill 8, 14, 24-25

LLlagoon 18lamprey 10lanternfish 22, 29limpet 26lionfish 11, 18littoral zone 6lobster

spiny 21squat 6

lobsters 8-9lobtailing 14logging 14loon 17low tide zone 26lugworm 27lure 22

MMmagnetic field 28manatee 20-21Marianas Trench 23mermaid’s purse 13mesopelagic zone 6-7

Mexico 28mid-oceanic ridge 6-7migration 20, 22, 24, 28

vertical 29molluscs 8murrelet 16mussel 8, 26-27mysticeti 14

NNOOnarwhal 25nautilus 8North Pole 24nudibranch 9, 18ocean 6-29octopus 8-9, 16odontoceti 15ooze 6, 22-23orca 14oxygen 10oyster 8, 16oystercatcher 16-17, 26

PPPacific Ocean 23, 29paddock 27parasites 14parrotfish 18-19pelagic zone 7penguin

Adélie 24-25emperor 24king 24-25

penguins 14, 16, 24-25petrel 16-17photosynthesis 6-7phytoplankton 6-7, 20pinnipeds 20-21plankton 7, 12, 22, 24plunge diving 16pod 15polar waters 24-25polyp 8, 18-19, 23, 26porcupine fish 10porpoise

harbour 14porpoises 12, 15prawn 26

predator 6, 10-12, 18, 20, 22, 24prey 10, 12, 14, 22-23pu"n 7, 16-17pup 24pursuit diving 17

RRrat-tail 23ray

electric 12manta 13sting 12-13

rays 10, 12-13, 18reef

barrier 18fringing 18

river 12-13, 28-29roots 20-21rorquals 15

SSsalmon 28-29Sargasso Sea 28scales 10-11, 12scallop 8-9school 10-11scorpion fish 21sea anemone 8-9, 18, 23, 26-27sea cucumber 8-9, 23sea horse 18, 20sea lettuce 26sea lion 14, 20-21sea otter 21sea pen 23sea slug 8-9sea snail 8-9, 26sea spider 23sea turtle 21sea urchin 8-9, 18, 21, 26-27seabirds 16-17, 24, 25seagrass 20 -21seal

bearded 24elephant 24harbour 21harp 24leopard 24-25

seals 12, 14, 20-21, 24seashore 6-7, 26

30 31

seaweed 9, 20, 26-27

shag 16shark

angel 12basking 12-13blue 12bull 12cookiecutter 12frilled 12goblin 12hammerhead 13mako 13milk 13nurse 13reef 13, 18saw 13thresher 13tiger 13whale 12-13

sharks 10-13, 18shearwater

short-tailed 28-29shellfish 8, 16, 25, 27shoal 11shrimp 7, 23, 25sirenians 21skates 13skua 17snake, sea 18-19South America 15South Pole 24Southern Ocean 24sponge

tube 18sponges 9, 23spouting 15spray zone 27spy-hopping 15squid

firefly 22giant 15, 22vampire 23

squid 8-9, 12-14, 16, 21, 22, 24-25

starfish crown-of-thorns 18

starfish 8, 26-27stonefish 10-11swim bladder 10-11, 23

TTtentacle 8-9, 18, 22, 26-27

ternArctic 28-29

terns 17tidal pool 16, 26-27tide 26-27triggerfish 18tripodfish 23tropicbird

red-tailed 17tube worm 6tuna 12turtle

green 20-21, 28-29turtles 20-21, 28-29tusk 14, 25twilight zone 6

VVWWZZvertebrates 10-11viperfish 22-23waders 17walrus 25webbed feet 16-17weedy seadragon 20whale

baleen 15beluga 24blue 14-15bottlenose 14bowhead 14grey 28humpback 14killer 14-15pilot 15right 15sperm 15, 22toothed 15

whales 10, 12, 14-15, 24-26whaling 15whelk 8-9winkle 9worms 8-9, 16, 23, 26-27zooplankton 6-7, 14, 22

IINNDDEEXX