Knowledge Encyclopedia Ocean

["90 cm (36 in) \u2013 the length of a newborn 10,000 The largest number of short-beaked 260 51m (853 ft) \u2013 the deepest dive of short-beaked common dolphin. common dolphins recorded in a gathering. a short-beaked common dolphin. Breathing apparatus Slippery skin The blowhole in the top A dolphin has completely of the head opens to suck hairless skin, so that it can slide in air whenever the seamlessly through the water. dolphin surfaces. A dolphin baby can suckle Shortened arm bones its mother\u2019s milk for Modified finger bones three years Flipper bones A dolphin\u2019s skeleton reveals how or sometimes even longer. it is distantly related to humans. Its flippers are made up of recognizable Pointed beak arm and hand bones \u2013 modified More than 250 by evolution into a paddle-like small pointed teeth shape for swimming. fill the mouth, or beak \u2013 perfect for grabbing fish. Balancing fin The dorsal fin helps stop the dolphin from rolling sideways in the water.","52 open ocean CETACEANS 200 years \u2013 the likely lifespan of the bowhead whale, the longest-lived cetacean. Cetaceans HOURGLASS DOLPHIN The biggest, fastest, and most intelligent marine animals are a group Lagenorhynchus cruciger of mammals called cetaceans. They include whales, dolphins, and Location: Southern Ocean porpoises, and most species live in the open ocean. Length: Up to 1.9 m (61\u20444 ft) Like all mammals, cetaceans breathe air and nourish their babies with milk. Swimming in the cold waters around Antarctica, Evolving from four-legged land animals, they developed flippers instead of feet, this ocean acrobat surfs the waves, jumping and smooth skins for easy swimming, and a horizontal tail fluke to flap up and down spinning in the air. Hourglass dolphins usually for propulsion. Most have teeth and eat fish, but the largest whales have filters in travel in groups of a dozen individuals and often their mouths called baleen plates, which trap microscopic food from the water. follow ships, keeping in their wake for up to half an hour. Flippers Spongy tool These help to control body The sponge protects the position and assist with slowing beak as the dolphin digs for food on the seabed. down when swimming. Male fin shape COMMON BOTTLENOSE SPECTACLED PORPOISE DALL\u2019S PORPOISE DOLPHIN Phocoena dioptrica Phocoenoides dalli Tursiops truncatus Location: South Atlantic, Location: Northern Pacific Location: Tropical and temperate oceans Length: Up to 2.4 m (8 ft) Length: Up to 3.8 m (121\u20442 ft) Indian, and Pacific oceans Length: Up to 2.2 m (71\u20444 ft) This restless porpoise could be the fastest cetacean One of the best known of all cetaceans, the common of all. At times, it reaches a speed of 55 km\/h bottlenose dolphin is intelligent and sociable. In Despite its striking body pattern, this secretive, (34 mph) in quick bursts. Dall\u2019s porpoise rarely Australia, females have learned to use a sponge to cold-water-loving cetacean is seldom seen because jumps from the water, but can be recognized by dig up prey from the seabed \u2013 a skill they pass on it rarely leaps above the surface. Females have the conspicuous V-shaped spray it sends from its to their daughters. a pointed dorsal (back) fin while in males this is blowhole as it surfaces. large and oval-shaped.","490 The number of North Atlantic right whales, 2,992 m (9,816 ft) \u2013 the deepest dive of any cetacean, 53 one of the most endangered whale species. achieved by a Cuvier\u2019s beaked whale. Long flippers bend Large domed BELUGA backwards with a head distinct \u201celbow\u201d Delphinapterus leucas LONG-FINNED PILOT WHALE Location: Arctic Ocean Length: Up to 4.5 m (15 ft) Globicephala melas Location: Atlantic, southern Indian, and The white-skinned beluga has been nicknamed the \u201ccanary of southern Pacific oceans the sea\u201d because it produces one of Length: Up to 6.7 m (22 ft) the widest range of sounds of any ocean mammal. It uses more than A type of giant dolphin, this cetacean hunts at 50 calls \u2013 including whistles, night for deep-water squid, sometimes diving squeaks, and clicks. down to more than 1,000 m (3,300 ft). At sunrise, pilot whales often gather in groups nearer the Skin is grey coloured surface to socialize while resting. in first year but turns whiter with age NORTH ATLANTIC RIGHT WHALE CUVIER\u2019S BEAKED WHALE PYGMY SPERM WHALE Eubalaena glacialis Ziphius cavirostris Kogia breviceps Location: Northern Atlantic Location: Tropical and temperate oceans Location: Tropical and temperate oceans Length: Up to 16.5 m (54 ft) Length: Up to 7 m (23 ft) Length: Up to 4.2 m (133\u20444 ft) Swimming through swarms of plankton, mouth Beaked whales lack baleen plates, and have Like its better-known giant cousin, this small, open, this whale traps its prey with its baleen very few teeth. The males of this species have toothed whale dives deep for squid prey. It may plates. Closing the mouth to flush out water, it a single pair at the tip of their lower jaw, which also hunt nearer the surface at night. Its pointed then swallows its meal. The whale usually moves protrude as mini-tusks. In females, teeth are not nose, underslung lower jaw, and long backward- slowly, resting near the surface for long periods. pointing teeth make it look similar to a shark, visible. Both sexes feed which may help deter bigger predators. by sucking squid into their mouths. PYGMY RIGHT WHALE HUMPBACK WHALE Caperea marginata Megaptera novaeangliae Location: Southern Atlantic, Indian, and Pacific oceans Location: Worldwide Length: Up to 6.5 m (211\u20443 ft) Length: Up to 17 m (553\u20444 ft) This is the smallest of the toothless baleen whales. One of the most widespread cetaceans, this baleen Though rarely seen, pygmy right whales may whale migrates long distances between its cold-water gather in numbers in the nutrient-rich feeding grounds around the poles and its breeding waters over continental shelves waters closer to the equator. One family group was and seamounts. tracked for more than 8,300km (5,160miles) from Costa Rica in Central America to Antarctica.","54 Fishing for squid Unusually for birds, albatrosses have a keen sense of smell \u2013 something they use to track shoals of squid or fish. Most prey is caught at the surface, but sometimes the bird must make a shallow plunge into the water to snatch it. Albatrosses also follow whales or fishing ships to pick up any leftovers. Long, narrow wings The vast wings use a lot of energy to flap, so the albatross avoids this when it can and relies on soaring to stay aloft. Wandering albatross Snowy plumage A full-grown albatross\u2019s There are not many birds that spend as much time at sea feathers are a brilliant white. as a wandering albatross. For months at a time, it soars Juveniles are dark brown with over the waves \u2013 only visiting land to breed. a white face, but become white as the bird matures. With a wingspan the length of a small car \u2013 one of the biggest of any bird \u2013 the albatross is perfectly equipped for riding Nostrils the air currents. It rises and falls as it glides, swooping Albatrosses and other ocean birds between giant ocean waves. Using this technique, consume a lot of sea salt along with it can cover long distances without ever flapping their prey. To stop this building up in their its wings, often travelling almost 1,000 km bodies, special glands in the head filter the (620 miles) in a single day. excess salt from the bird\u2019s blood so that it can be expelled through their nostrils. Hooked bill A large, strong bill is needed for Nasal salt gland grabbing slippery squid and fish. The tubular nostrils point forwards Duct to help pick up the scent. Salty secretion Giant warty squid A favourite prey species Nostril of the albatross, this squid can grow to 1 m (31\u20444 ft) in length, but the bird targets smaller individuals.","55 km\/h (34 mph) \u2013 the top soaring 55 speed of a wandering albatross. Black-tipped wings Adult male albatrosses have dark areas on their wings and tail. Females have these patches too, but also have more brown on the rest of their bodies. Massive wingspan When both wings are fully extended, the bird\u2019s wingspan can stretch up to 3.5 m (111\u20442 ft) wide. BIRD WANDERING ALBATROSS Diomedea exulans Location: Southern Ocean Body length: Up to 1.35 m (41\u20442 ft) Diet: Mainly squid, cuttlefish, and icefish Soaring over the ocean Lots of birds save energy by gliding \u2013 staying in the air without flapping their wings. Gliders eventually lose height, but albatrosses and some other birds can use the winds to stop this happening, or even to rise higher. This is called soaring flight. As albatrosses fly over the ocean, they face into the wind, which helps them gain height. Once they reach a certain height, they turn and glide downwards with the wind, before repeating the action over again. Short legs Wind 3. Rising back up The legs of an albatross are direction As wind blows over the strong enough to support the weight of this big bird on land, albatross\u2019s wings once but their short length makes more, it provides the the bird sway from side to side as it walks. bird with lift, helping it rise to 15 m (50 ft) above the ocean. The wandering albatross mates for life, flying across the ocean to breed with the same bird every two years. Webbed feet 1. Gaining height 2. Drifting down When settled on the ocean Flying close to the When the bird turns surface, the albatross kicks ocean surface, the away from the wind, back with its webbed feet, it drifts downwards. albatross turns Before it reaches the which push through the into the path of ocean surface, it turns water to propel it forwards. the wind, which to catch the wind again. pushes it upwards.","Sargasso Sea In the North Atlantic Ocean, 1,000 km (620 miles) from the coast of the United States, is a vast patch of ocean called the Sargasso Sea, where the waters are strangely calm. The Sargasso Sea is at the peaceful centre of a swirl of currents called a gyre. This sea within an ocean \u2013 the size of the Caribbean \u2013 is bordered by choppy waves instead of land. Much of it is covered with a floating seaweed called sargassum, which provides shelter, food, or even breeding grounds for many ocean animals \u2013 from fish and baby turtles to humpback whales and seabirds.","","58 open ocean TWILIGHT ZONE 1 per cent of sunlight reaches the top of the twilight zone, 200 m (660 ft) below the surface. Mighty movements A flick of the viperfish\u2019s long tapering body propels it forwards so it can quickly grab prey in the dim light. Luring prey Twilight zone A long ray stretching from At a certain depth in the ocean, it gets too dark the dorsal (back) fin of a for algae to grow, but if the water is clear, just viperfish ends in a luminous enough light reaches down for animals to see. lure to attract prey. This is the twilight zone, a huge area that reaches from about 200 m (660 ft) to 1,000 m (3,300 ft) deep. Without algae to make nutrients by photosynthesis, animals rely on food that comes down from above. Many of the creatures that live here have special adaptations that allow them to thrive in this low- light environment. Gaping jaw Viperfish The viperfish can open its jaws more than 120 This lethal fish uses a luminescent (light-emitting) lure to draw in unsuspecting prey. But predators degrees, helping it to hunting in the gloom need to be sure that any prey swallow prey more than caught can\u2019t escape. When the viperfish closes its half its own body length. wide jaws around a target, its long fangs trap the prey in its mouth like a cage, so it cannot reverse. Using bioluminescence Terrifying teeth When living things generate light, The fang-like teeth of the viperfish are the this is called bioluminescence. The longest in proportion to body size of any light is produced by a chemical fish. They sit outside the fish\u2019s mouth when reaction that is often controlled by closed and reach up to its eyes. bacteria that live in the animal\u2019s skin or in special capsules, such ATTACK DEFENCE as the lure of an anglerfish. Some animals use light to signal to their Lure Smokescreen own kind, but many also use it The light-producing Some animals release when they hunt for prey or to reaction of some deep- a cloud of light-producing defend themselves from predators. sea fish is contained in a chemicals, which special bulb that acts as conceals them as they a lure to attract prey. escape from predators. Shock Counter-illumination A flash of bright light in By concentrating the the gloomy twilight zone glowing light along their can stun prey, leaving it underside, animals can confused and more obscure their shadow so vulnerable to attack. they are harder to see.","500 trillion \u2013 the estimated number of bristlemouth, a twilight zone 95 per cent of the weight of all the fish in the 59 fish that could be the world\u2019s most abundant backboned animal. oceans can be found in the twlight zone. Barreleye fish The eyes of many twilight zone animals are big to collect the light. The barreleye fish has large tubular eyes that can move upwards, but it also has a transparent head so even more light reaches the extra sensitive cells on the retina at the back of its eyes. Letting in light Illuminating organs The skin of the barreleye fish Light production in the skin of and the top of its skull are bioluminescent animals is made of transparent tissue. concentrated in spot-like organs called photophores. The Moveable eyes photophores are under the The eyes can point control of the nervous system, forwards or upwards to which flashes them on and off. look for prey or predators. Blue luminescence Flashing camouflage Each photophore shines Sometimes the squid will flash with a blue light. Unlike many brighter underneath to conceal animals, which rely on bacteria to produce this light, the firefly itself from bigger predators squid produces the light inside below that look upwards its own cells. into the sunlight. Firefly squid Some animals make their own light using special organs in their skin called photophores. The firefly squid can flash its lights on and off, which sends a visual signal to attract prey or a potential mate.","60 open ocean GIANTS OF THE DEEP 8 kg (18 lb) \u2013 the weight of a sperm whale\u2019s brain \u2013 the largest brain of any animal. Giants of the deep Skin scratches Circular scars and tears The world\u2019s biggest toothed predator is a giant whale that plunges far down into the depths of the ocean may be left by the to hunt for squid that can grow to the length of a bus. suckers and hooks of By holding its breath for an hour or more, a sperm whale descends the colossal squid. into the darkness. When vision becomes impossible, it starts using sound to home in on prey, sometimes coming across a formidable target: the colossal squid. This massive mollusc is the biggest animal without a backbone, and fights back with tentacles armed with vicious hooks and suckers. mammal SPERM WHALE Physeter macrocephalus Location: Oceans worldwide Length: Up to 19.2 m (63 ft) Diet: Mainly squid, sometimes fish Muscle layers Spermaceti organ Junk Lower jaw Sound generator The whale\u2019s nose carries parts that help it both communicate with other whales and detect prey by echolocation (see pp.148\u2013149). In the spermaceti organ, clicking sounds the whale produces are bounced around, and the junk then focuses them as a beam out into the ocean. Bulky snout The gigantic nose makes up about a third of the animal\u2019s entire length. Battle scars Long marks on the head of the whale come from clashes with other territorial males in the deep ocean. Sperm whale Many whales use their huge mouths to strain small animals from the water, but sperm whales have a massive toothy bite instead. Squid are their favourite prey \u2013 they catch more than 30 in a single dive and around 750 each day. Males \u2013 which are bigger than females \u2013 catch the bigger species, such as this colossal squid.","24 The number of hooks on each 61 tentacle of a colossal squid. Tiny eyes Powerful tail Small eyes on the side The sperm whale lifts of the head are set so its tough triangular tail far back that the whale fluke high into the air cannot see directly before making a dive. ahead of its huge nose. Attacking arms Deadly hooks Four pairs of arms inflict One pair of long tentacles damage using suckers is tipped with clubs armed and hooks, but are shorter than the with swivelling hooks. two long tentacles. Colossal squid Living in the perpetual darkness of the deep ocean and snatching up fish with its long tentacles, the colossal squid is a fearsome predator. But this giant cephalopod is elusive and rarely seen. Much of what we know about it comes from the hard remains found in the stomachs of sperm whales. Sharp beak The hard beak can effortlessly bite through the flesh of prey. Human eye Whale eye Squid eye Squid eye Each of the colossal squid\u2019s eyes is about the size of a football \u2013 the biggest eyes of any animal. They contain special glowing organs that act like flashlights to scan the water for fish. Cone-shaped teeth mollusc The whale\u2019s narrow lower jaw carries up to 26 pairs COLOSSAL SQUID of conical teeth. There are no properly developed teeth Mesonychoteuthis hamiltoni in the wider upper jaw. Location: Southern Ocean Length: Up to 9 m (291\u20442 ft) Diet: Fish and smaller squid","62 open ocean MIDNIGHT ZONE 17,000 The number of animal species so far recorded living in the midnight zone. Midnight zone GULPER EEL Sunlight cannot penetrate more than a kilometre below the surface of the ocean, so it is as dark as midnight at the greatest sea depths. Eurypharynx pelecanoides In this alien world live some of the strangest ocean animals of all. Location: Deep oceans worldwide Length: Up to 75 cm (291\u20442 in) Life is a challenge in the deep. Water pressure near the seabed is high enough to crush a car and temperatures can plummet to near freezing. The gulper eel swims with its huge, hinged In this cold, black habitat food can be scarce, so animals make the most mouth wide open in order to trap lots of small of what they can find and may go for long periods without eating. animals at once. It releases excess water through gill slits on the sides of its head. Flexible jaw The loose hinge of the jaw allows it to open very wide to trap as many small animals as possible. Expandable stomach Jagged teeth Stretchy skin and stomach lining Sharp, backward- pointing teeth help the digestive cavity to ensure that prey consume prey twice its length. cannot escape when the mouth BLACK SWALLOWER is closed. Chiasmodon niger Luminous lure Location: North Atlantic A fleshy bulb, Length: Up to 33 cm (13 in) called an esca, contains a Living up to its name, this slender fish has capsule with a stomach that can expand dramatically to light-producing accommodate fish prey much bigger than bacteria. the swallower itself. GIANT ISOPOD Bathynomus giganteus Location: W. Atlantic and Caribbean Length: Up to 50 cm (193\u20444 in) The giant isopod is a relative of the woodlouse, but the size of a small dog. Despite its fierce appearance, it is a harmless scavenger that grubs around on the ocean floor to look for food. BEARDED SEA DEVIL Linophryne densiramus Location: Atlantic and Pacific oceans Length: Up to 9 cm (31\u20442 in) This fish uses a luminous lure to attract inquisitive prey, which it then grabs with its big mouth. The light in the lure is produced by bacteria that live in the fish\u2019s flesh, and can also be found in its glowing beard.","90 per cent of the ocean\u2019s water 167 The number of species of deep-sea anglers, 8,000 m (26,250 ft) \u2013 the depth of the deepest 63 lies in the midnight zone. the biggest group of deep-sea fish. recorded fish, the Mariana snailfish. TAN BRISTLEMOUTH DUMBO OCTOPUS Cyclothone pallida Grimpoteuthis sp. Location: Deep oceans worldwide Location: N. Atlantic and Pacific Length: Up to 7 cm (23\u20444 in) Length: Up to 48 cm (19 in) These fish have light-producing organs along Like other octopus, the dumbo octopus squirts their sides to help them communicate with other water from a siphon to keep moving. But it also fish in the dark water. They also produce chemical has a pair of ear-like fins to control its position scents called pheromones to attract mates. as it hovers over the ocean floor to search for prey, such as worms and shrimps. VAMPIRE SQUID HELMET JELLYFISH Vampyroteuthis infernalis Location: Deep oceans worldwide Periphylla periphylla Length: Up to 30 cm (12 in) Location: Deep oceans worldwide The umbrella-like vampire squid is named for its Diameter (of bell): Up to 15 cm (6 in) blood-red colour rather than its behaviour. It drifts in the dark ocean depths eating other invertebrates Fleshy fins This jellyfish can switch on light-producing and the remains of dead animals and plants. It uses Fins move up and organs in its glassy bell when it senses a the suckered tips of its arms to transfer food into down to help the disturbance. It is thought it does this to its mouth. octopus control its scare off predatory fish and shrimp. position in the water. SEA PIG ZOMBIE WORM Three-legged tripod Bony, stilt-like fin rays Scotoplanes globosa Osedax priapus support the weight of Location: Deep oceans worldwide Location: Pacific the fish at rest. Length: Up to 10 cm (4 in) Length: Up to 1.5 cm (5\u20448 in) TRIPOD FISH The scavenging sea pig is a distant This tiny worm burrows into relative of the starfish. It belongs to a group the bones of dead whales and Bathypterois grallator of soft-bodied animals called sea cucumbers feeds on the fat locked inside. Location: E. Pacific, Atlantic, and uses sucker-like feet to crawl on the It has root-like structures seabed, sometimes in huge herds. instead of a stomach, which and W. Indian oceans contain special bacteria that Length: Up to 40 cm (153\u20444 in) help with digestion. The tripod fish uses two long fin rays Whale bone and a tail ray to rest on the ocean bottom. In this way it can save energy while it waits for tiny planktonic prey to come along.","64 open ocean HYDROTHERMAL VENTS 500 The number of hydrothermal vent fields known to exist in the oceans. Hydrothermal vents Deep at the bottom of the ocean are cracks where hot water shoots upwards through the ocean floor. Called hydrothermal vents, they form rocky chimneys that are home to some of the most unusual food chains on Earth. Rising from the seabed, hot water spews from chimneys in clouds of either white or black smoke. This water comes from under the ocean crust where it is heated to temperatures of 400\u00b0C (750\u00b0F ). Both the water and the chimneys contain a host of chemicals and minerals from deep inside Earth, which provide an important source of energy for the creatures that live without sunlight at these great depths. Volcanic food chain Dandelion siphonophore This relative of the Growing on the walls of the chimneys, bacteria can turn carbon dioxide into food \u2013 like plants do \u2013 but instead of Portuguese man o\u2019 war has using energy from light to do this, they get energy from a flower-like body and chemical reactions. In this unique habitat, these bacteria form the bottom of extensive food chains of animals that swims around the vents, live entirely independently of sunlight \u2013 mussels, worms, catching tiny animals. crabs, and even the occasional fish. How hydrothermal vents form Pompeii worms Short tube worms Cold ocean water can seep down through cracks in the called Pompeii worms, rock of the ocean floor. As it gets deeper, it is heated by with a star-like fan magma (molten rock), and minerals from the rocky crust dissolve into the hot water. Eventually, pressure builds up, of tentacles, can forcing the water back upwards. As it hits the ice-cold tolerate the extreme water above the ocean floor, the minerals it carries turn solid, building up over time to create chimneys. The water heat and live on erupts from these in what looks like plumes of smoke. the chimneys. Cold water seeps The superheated water Chimney down through rises back up through Chimneys are made cracks in the fissures in the ocean up of minerals such seabed into the crust, carrying dissolved as iron sulfide that ocean crust minerals that solidify to form chimneys solidify from hot seawater as it rises, over time building up into tall towers. Nutrient-rich water Water spewing up through the vent contains hydrogen sulfide \u2013 a gas that smells like rotten eggs \u2013 which is used by bacteria as a source of energy to make food. Hot water The water that emerges through the vent in the ocean floor is at least 60\u00b0C (140\u00b0F) and usually much hotter.","5,000 m (16,400 ft) \u2013 the depth of the Cayman Trough in the Caribbean 60 m (200 ft) \u2013 the height 65 Sea, the site of the deepest-known hydrothermal vents. a chimney can grow. Black smoker The chimney\u2019s distinctive dark smoke is formed from water and tiny black particles of iron sulfide. Signs of bacteria As bacteria use up chemicals spewing from the chimneys, their food-making chemical reactions leave waste products, such as yellow sulfur, that accumulate in patches on the chimney walls. Cusk eel This species is one of the deepest-known living fish and may be an occasional visitor to hydrothermal vent habitats. Tube worms Giant tube worms are one of the main animals found around Pacific Ocean vents. They can grow to 3 m (10 ft) in length. Plume Heart Blood vessels White vent crabs Giant white clams Main body These small crustaceans feed Each growing up to 26 cm (101\u20444 in) Giant tube worms on bacteria and other tiny long, these live in dense colonies Many animals living around the vent organisms living around around the base of the vents. They carry their own food-making bacteria. the vents. are nourished by food-making Giant tube worms lack a gut and bacteria that live in their gills. instead use their plumes to collect chemicals, which blood vessels transport to the bacteria living inside cells within the worm\u2019s main body.","Deepsea Challenger Floodlights Deepest dives Deepest scuba dive: 66 open ocean EXPLORING THE OCEAN A panel of floodlights 332 m (1,089 ft) This bullet-shaped submersible was designed illuminates the dark Deepsea Challenger is to travel to the deepest part of the ocean \u2013 deep ocean. Their light one of many submersibles Submarine dive Challenger Deep, right at the bottom of the can penetrate up to built to explore the ocean. (USS Seawolf): Mariana Trench in the Pacific Ocean. In March 30 m (100 ft) if the Crafts specifically designed 490 m (1,618 ft) 2012, Canadian filmmaker James Cameron water is clear. to reach the deepest depths piloted the submersible on its voyage have to survive greater and became Challenger Deep\u2019s pressures and carry a Deepest diving first solo explorer. The craft source of oxygen with mammal spent three hours on the ocean them. The Trieste was the (Cuvier\u2019s beaked floor and collected samples first to travel down the whale): 2,992 m of rocks and animals for deepest ocean trench back (9,816 ft) scientists to analyze. in 1960, but in May 2019, American explorer Victor Jiaolong Submersible body Vescovo in DSV Limiting submersible: The main body of the Factor broke all records 7,200 m (23,622 ft) submersible is made of a by reaching a depth of foam consisting of glass 10,928 m (35,853 ft). Deepsea Challenger: beads embedded in a resin. 10,908 m (35,787 ft) This specially designed Limiting Factor: 10,928 m material can resist the high (35,853 ft) Trieste: 10,914 m pressures of the deep ocean. (35,807 ft) Batteries Exploring the ocean The number of new species identified An array of 70 batteries arranged in three packs The deepest parts of the ocean \u2013 with their bone- 68 due to Deepsea Challenger\u2019s research. powers the submersible. It crushing pressures and their cold, dark water \u2013 can keep running on just are inhospitable. But humans have explored this one pack in an emergency. strange world in tough underwater vehicles called submersibles. Spotlight One long metal pole carries The deepest humans can dive without any special equipment is little more than 100 m (330 ft). Armour-like suits allow a spotlight that the pilot divers to go a little deeper, but to travel any further they need can position to illuminate to ride in an underwater vehicle. Submarines, which creatures on the seafloor. are stocked with enough food, fuel, and oxygen, can carry their crew for months at a time. Smaller submersibles rely on a boat at the surface for support, but are designed to go much deeper \u2013 right into the trenches that make up the deepest parts of the ocean. Thrusters Two types of thrusters sit on the sides of the submersible. Some propel the submersible sideways. Others propel it upwards and downwards.","Cockpit Controls m (24 ft) \u2013 the full height of the The pilot sphere, or The pilot has access to a range of cockpit, carries the equipment, including a touchscreen, 7.3 Deepsea Challenger submersible. one-person crew and and joysticks to command the has a pressure-resistant submersible\u2019s 12 thrusters. hours \u2013 how long the pilot can breathe using viewing window. Camera 56 Deepsea Challenger\u2019s two oxygen tanks. A second pole carries a high- Pilot This submersible definition camera \u2013 one of has only room for a eight in total, which are single human pilot, who cannot stretch mounted both outside and their legs or arms. inside the submersible. They monitor and operate the craft\u2019s Collecting arm A tool for collecting external arms. samples works like a vacuum cleaner to suck Weights up samples of life forms, Steel ballast weighing sediments, or rock. more than 450 kg Sample storage (1,000 lb) weighs Samples collected for scientific study the submersible down are put in a plastic box mounted on so that it sinks. The the front of the submersible. ballast is released to make the craft rise Deepsea Challenger took around back to the surface. two and a half hours Payload bay The part of the to reach the bottom of Challenger Deep. submersible below the pilot sphere is called the payload bay. It is used to collect samples from the deep ocean for scientific study. Stabilizing fin 67","68 Camouflage White plumage helps to camouflage the Arctic tern against the snow of polar habitats. In flight Long, narrow wings are good for hovering in the air before diving for fish, as well as for gliding on ocean breezes. Flight control The Arctic tern\u2019s wide tail, with long streaming side feathers, is used to control the position of the wings, as well as to help with braking when landing. Migration The total distance an Arctic tern will typically fly during its lifetime equals Some of the longest journeys in the animal kingdom are made by animals that migrate around the oceans \u2013 either three or four trips to swimming below the surface or flying high above it. the Moon and back. Migrations happen when large groups of animals travel together at Champion migrator the same time and move from one place to another, then back again in a predictable routine. Some animals have migrations that are short No animal migrates as far as the Arctic tern. After and frequent, such as plankton that migrate daily between shallower breeding in the Arctic, this bird journeys to the and deeper waters, or invertebrates that move with the tides. But opposite side of the world to feed in the Antarctic. many ocean-going animals undertake yearly journeys across vast It times its journeys to coincide with the two polar distances between different feeding and breeding grounds. summers, which means it probably sees more daylight hours than any other species.","20,500 km (12,740 miles) \u2013 the distance covered by leatherback 96,000 km (59,650 miles) \u2013 the total yearly distance 69 turtles as they travel between foraging grounds in the Pacific. the Arctic tern travels during its migration. 1 Breeding grounds Between May and July, the Arctic summer, Arctic terns breed in colonies of up to 300 birds. It takes 6 weeks for the terns to incubate eggs and raise their young so they are old enough to fly and ready to join the migration. 2 Flying to the Antarctic The Arctic terns flying south over the Atlantic follow two possible routes \u2013 one along the coastline of Africa, and another along the coastline of South America. 3 Feeding grounds November brings winter to the Arctic and summer to the Antarctic. The terns are arriving in Antarctica, where they rest and feed. At the height of the polar summers, the Sun doesn\u2019t set \u2013 so for much of the year these birds do not experience dark nights. 4 Flying to the Arctic When the birds fly northwards, they take a route that is further out to sea and away from the coastlines. End-of-life migration Tidal migration Vertical migration At the end of their lifetimes, European eels As a rising tide covers the shore, underwater Tiny planktonic animals rise to feed near the journey from fresh water to the Sargasso Sea animals follow the water to feed over the surface at night, but sink during the day to in the Atlantic Ocean to spawn and then die. flooded seabed. When the tide ebbs, avoid predators. There are so many plankton The young eels (pictured) migrate back to shorebirds move further down the shore to that their total weight could make this daily Europe and grow to maturity in rivers. prey on invertebrates burrowed in the mud. migration the biggest on the planet.","","SHALLOW SEAS The areas of the ocean that lie between the shore and deeper water are known as shallow seas. They cover only 8 per cent of Earth\u2019s surface, but because light and food are so plentiful here, these fertile shallow waters are home to an incredible number of animal and plant species.","72 TROPICAL AND TEMPERATE SEAS SUNLIT There are shallow seas in the polar regions, but most are in SEAS temperate or tropical zones (see p.9). Tropical shallow seas feature warm clear water, corals, colourful fish, and white Every continent is edged by a shelf of land that sand, while colder murky water, with kelp forests and lies submerged beneath the ocean and is known as silvery or brown fish, is typical of temperate seas. the continental shelf. These shelves create shallow seas, no more than 200 m (660 ft) deep, which often Temperate waters can be warmer than the open ocean and rich in oxygen and nutrients. Sunlight penetrates all the Between the icy polar regions and the hot tropics lie the way to the seafloor of these coastal waters unless temperate ocean zones of the Northern and Southern they are very muddy, and as a result, they are hemispheres. Water temperatures here fluctuate with usually teeming with life. the seasons, ranging from 10\u00b0C (50\u00b0F) to 20\u00b0C (68\u00b0F). Many species make seasonal migrations as temperatures change. Fine catch Murky water Most commercially important fish Cold water is species, such as cod and mackerel, often full of are found in temperate seas. phytoplankton which make it look less clear. SUNLIT ZONE Large shoals Fish thrive The top layer of the ocean, where sunlight reaches, is due to the known as the sunlit zone. All water above the continental high density shelf is within this zone. Organisms that get energy from of plankton. the Sun, through a process known as photosynthesis, thrive here. In shallow seas, these organisms include seagrass, Muddy, sandy, the algae that live inside coral polyps, and other algae and or rocky microscopic phytoplankton that together form an abundant seabed and important first link in the food chain as they become food for animals further up (see pp.34\u201335). Nurseries Light Tropical waters In the shallowest parts, In clear water, sunlight seagrass and coral reefs reaches all the way The regions of the Atlantic, Pacific, and Indian oceans bordering provide sheltered nurseries down to the seafloor, the equator are tropical seas. Water temperatures here remain for many species. even at 200 m (660 ft). relatively constant at 20\u201325\u00b0C (68\u201377\u00b0F). Since there are fewer and less pronounced seasons, tropical species follow other signs, such as lunar cycles, for mating and spawning. The diversity and number of species in tropical waters is stunning. 0 M\/ 0 FT Crystal clear water Waters are clear due to low levels of nutrients and plankton. Seagrass 100 M\/ Bold colours meadow 330 FT Tropical fish are often colourful, Coral reef matching the vibrant coral reefs. Food for plankton 200 M\/ Crowded reefs Nutrients from soil, rivers, and 660 FT Many species the seabed are spread through have developed the water by tides, currents, and behaviours or upwelling (see p.23), providing body forms that help them live food for phytoplankton. closely together on the reef. Muddy seafloor Continental shelf Thick layers of sediment cover The continental shelf varies in width and depth. At its edge, the most of the continental shelf. seafloor slopes down towards Seagrass and seaweed don\u2019t the dark depths of the open ocean. grow far below 100 m (330 ft).","73 SHALLOW SEAS HABITAT CORAL REEF TYPES Shallow seas are often characterized by Coral reefs are divided into three main what the seafloor is like \u2013 hard and rocky, types based on how they form. The most soft and muddy, or covered in living common type of reef is a fringing reef, structures such as corals. The seafloor is lining the shore. Some of the most iconic where most species feed, hide, and mate, reefs are those that form a barrier further so the environment determines what offshore, such as the Great Barrier Reef and organisms live there. the Belize Barrier Reef. The third type of reef is an atoll. Circular or oval, atolls are Fringing reef all that remain of a submerged volcanic These reefs form around the edges of islands island (see p.18). and continents, extending from the shore. Sandy coral cay (see pp.118\u2013119) Rocky seabed Rocky habitats have lots of nooks and crannies for marine species to live in, especially those that can attach themselves to hard surfaces. Barrier reef Atoll Barrier reefs also form parallel to the coast, but Fringing reefs surrounding volcanic islands much further out, with deep water in between. become atolls if the island itself submerges. Coral reef SOUNDS OF THE REEF Mostly found in tropical waters, coral reefs create a stable and protective habitat for thousands of Coral reefs aren\u2019t just colourful, they tropical fish and invertebrate species. are also full of noise. Reef species make many different sounds, when eating, mating, showing aggression, or communicating with each other. With the latest recording equipment, divers can collect these noises so that scientists can study how important sounds are for a thriving reef. Sandy plain SOFT AND HARD CORAL This environment, constantly being reshaped by currents and waves, offers an ideal hiding place Corals are grouped into two main types \u2013 hard and soft. The polyps for species who can burrow in the sand. of hard corals secrete a hard calcium-based skeleton that builds up reefs (see p.99), while soft corals contain spiny, pin-like structures within their bendy tissues that give them support and deter predators. Seagrass meadow Hard coral Soft coral Seagrasses provide food for grazing sea Hard coral species are reef-building, with Soft corals contribute less to reef structure. creatures and serve as a nursery and a shelter living polyps adding new, expanding layers Many species look like colourful plants or from predators for many smaller species. to the dead skeletons of older corals. delicate fans or grasses.","74 shallow seas KELP FOREST Kelp forest In cool, clear coastal waters around the world, spectacular underwater forests of giant kelp support a rich variety of animals, including sea otters, seals, and even whales. Large seaweeds known as kelp grow in the shallow coastal seas of all cool oceans. Many form dense low-lying kelp beds that extend far offshore, hidden beneath the waves. But on some coasts, incredibly long fronds of giant kelp grow all the way to the surface through the clear water, creating submerged forests that provide food and shelter for a specialized community of marine life. Kelp harvest Monterey Bay Kelp is harvested around the world for special Just south of San Francisco, chemicals called alginates that are used in USA, the sheltered waters producing food, clothing, and paper. It is part of Monterey Bay conceal an of Japanese and Korean cuisine, and there is underwater jungle of giant growing interest in using kelp as a biofuel. Each kelp. Anchored to the seabed year, thousands of tonnes of kelp are harvested. by their claw-like holdfasts, the kelp form a forest of vertical stems that grow 50 m (164 ft) or more through the water to trail their leaf-like blades on the sunlit surface. Harbour seal Diving harbour seals hunt the many types of fish that feed and shelter among the kelp fronds. Types of seaweed Olive rockfish Spiny-finned rockfish hang There are three main types of seaweed in the ocean, classified by their colour. They all beneath the kelp canopy, live by absorbing the energy of sunlight and preying on tiny shrimp-like using it to make food by photosynthesis. animals and small fish. Green seaweed These seaweeds are often Growing tall delicate and have green Giant kelp can grow at the fronds that look like the leaves of land plants astonishing rate of 60 cm such as lettuce. (24 in) a day, in order to reach the sunlit surface Red seaweed as soon as possible. Usually found in dimmer waters and shady tide Sea urchin pools, the red seaweeds Spiny sea urchins eat the include coraline seaweeds kelp, and may completely that help build coral reefs. destroy it if there are Brown seaweed no otters to keep their The brown seaweeds include numbers under control. all the largest species, such as kelp and wracks, and often have broader fronds.","75 Sleeping support Resting otters wrap themselves in kelp to avoid floating away. Sea otter Sea otters live and sleep on the surface of the sea above the kelp forests. They are an important part of the ecosystem, as they prey on sea urchins \u2013 one of the main consumers of kelp. Balloon-like sacs The air inside the bladders is a mixture of oxygen, nitrogen, and carbon dioxide. Bladders Gas-filled bladders at the base of the leaf-like blades make the tip of each strand float near the surface. This enables the kelp to soak up the vital sunlight it needs. Prickly prey The needle-like spines of sea urchins are no defence against sea otters, which use stones to crack open their shells. Holdfasts At the base of each stem a root-like holdfast grips a rock or other solid object to stop the kelp being swept away by the current.","76 shallow seas SEAGRASS MEADOW 10 litres (352 oz) \u2013 the amount of oxygen that 1 sq m (10 2\/3 sq ft) of seagrass can produce in one day. Seagrass meadow Light Like all plants, seagrass Seagrasses are flowering plants that have, over needs light and can only millions of years, adapted to living in the ocean. grow in shallow, clear waters They form large seagrass meadows, which are where light is abundant. very important habitats that are now under threat. Seagrass provides shelter for small animals in what would otherwise be a barren sandy-bottomed seascape. The sediment and decaying matter trapped by the roots of the seagrass provide nutrients for invertebrates. Juvenile fish hide behind the green blades while picking off invertebrates and, in turn, attract bigger fish, and so a large community builds up around the meadow. Once common in shallow waters across the world, many meadows have been lost due to coastal development and pollution. Green sea turtle Seagrass is a major part of the green sea turtle\u2019s diet. An adult will eat 2 kg (41\/2 lb) every day. Turtle grass A favourite grass of green sea turtles, turtle grass has a flat, broad ribbon-like blade that can reach 35.5 cm (14 in) in length, and has an extensive root system. Queen conch About 30 cm (12 in) long, these giant sea snails are the cleaners of the seagrass meadow, eating up dead grass. CARBON CAPTURE C02 Carbon dioxide Seagrass against Seagrass C02 C02 (greenhouse gas) climate change is absorbed by seagrass Seagrasses harness the Sun\u2019s light to make food Dead 02 02 through photosynthesis. Sharptail eel vegetation In this process, the Often mistaken for sea 02 seagrass absorbs carbon snakes due to their lack Roots Oxygen is dioxide and releases released oxygen. The carbon is of fins, these fish use c locked into the plant their pointy snouts to c c c tissue. When a plant dies Seahorse cc c it is buried in the seabed, burrow in the sand. Seahorses cannot swim c trapping the carbon. against strong currents, so Trapped This makes the seagrass anchor themselves by wrapping carbon meadow an efficient their tail around seagrass. processor of carbon dioxide, one of the gases that cause climate change.","2 football fields \u2013 the area of seagrass meadow 4,500 sq km (1,737 sq miles) \u2013 the area of the world\u2019s 77 lost every hour due to human impact. largest-recorded seagrass meadow, in Australia. Spotted sea trout Manatee Sunlit underwater meadow This is one of many species of fish Known as the cows of the seas, that spends its life as a juvenile in manatees are large marine mammals. There are many different species of seagrass, seagrass meadows where food They spend up to a quarter of their but all of them are green plants that need and shelter are both plentiful. time feeding, grazing both day and sunlight to grow. In this seagrass meadow on night at depths of about 2 m (61\u20442 ft). the coast of Florida, USA, two species provide nutritious grazing for manatees and green sea turtles. They are joined by a number of other animals coming here to feed, shelter, or hunt. Red cushion starfish Suckling calf Setting root Moving across the seabed, A manatee calf suckles Part of the seagrass stem red cushion starfish graze on from teats on the underside spreads underground, of its mother\u2019s flippers. forming a network that algae, sponges, and small Weaned at about one year holds sediment in place. invertebrates. Seagrass old, it remains close to Known as a rhizome, it its mother for up to two produces both new shoots meadows provide perfect and anchoring roots. shelter while the starfish years after birth. develop from larvae to their Clingfish shelter Manatee grass adult, five-limbed shape. The pelvic fins of this This species of seagrass tiny emerald clingfish takes its name from the form a sucking disc that manatees that love to eat it. enables it to cling to The cylindrical blades can blades of seagrass, out grow to 50 cm (20 in) long. of sight of most predators.","78 shallow seas COMMON CUTTLEFISH Three hearts pump blue-green blood around a cuttlefish\u2019s body and gills. Fin The muscular fin Head ripples like a skirt, moving the cuttlefish in any direction. Mantle Everything behind the head of a cuttlefish is known as the mantle. It contains the cuttlebone, the water-filled mantle cavity, and all organs except the brain. Eye Cuttlefish eyes are very large in proportion to their body. They have a very distinct W-shaped pupil. Cuttlefish can see aspects of light that are invisible to human eyes. Colour-changing skin Beak Siphon The parrot-like beak can Cuttlefish expel water Three types of colour-changing cells in the crunch through the shells of through their siphon to surface layers of cuttlefish skin \u2013 yellow, red, prey and is a good defence quickly escape predators. and brown \u2013 combine to produce multiple Ink produced in an internal colour changes. A cuttlefish can quickly against predators, too. ink sac is also squirted out stretch certain cells out, much like blowing through the siphon to help up a balloon, to make some colours brighter, confuse attackers. enabling it to change skin colour in a flash. Common cuttlefish Cuttlefish belong to the same group of molluscs as squid and octopus. All have multiple arms and a mantle, but cuttlefish have a broad, stout body, containing a cuttlebone, and move more slowly. Common cuttlefish are mostly active at night, usually spending their days partly buried in the sandy seabed. Like all cuttlefish, this species is well known for its camouflage abilities, changing not only the colour of its skin but also the texture in order to match its surroundings.","2 years \u2013 the maximum expected 4,000 The maximum number of eggs laid by the 79 lifespan of a common cuttlefish. female common cuttlefish before she dies. Crab catcher Moving in all directions A common cuttlefish puts on colourful skin displays and Cuttlefish move their fins to travel backwards or forwards slowly. waves its arms to confuse a crab. Once the crab is within For quick escapes they use jet propulsion \u2013 they suck water into reach, the cuttlefish shoots out its tentacles. Suckers on their mantle cavity and quickly shoot it out through their siphon. the end of the tentacles lock onto the crab\u2019s shell just long To make movements up or down they increase or decrease the enough for the eight arms to grasp it and bring it toward amount of gas in their cuttlebone. the cuttlefish\u2019s shell-crushing beak. Cuttlebone This porous internal shell has chambers filled with gas and water. Fin Mantle Water cavity pushed out Arm Jet-propelled swim direction Siphon Once the cuttlefish captures its prey with its tentacles, mollusc it uses its eight sucker-lined arms to grasp it and bring COMMON CUTTLEFISH it toward its beak. Sepia officinalis Location: N.E. Atlantic, Baltic Sea, Mediterranean Length: Mantle up to 49 cm (191\u20444 in) Diet: Molluscs, crabs, shrimp, worms, fish Tentacle Suckers Cuttlefish have two tentacles Tentacles only have suckers that they fire out from a at the end, where there are pocket at the base of their clusters of differently sized arms to capture prey. suckers to help snare prey. Prey Crustaceans, such as this European spider crab, are a favourite prey, though the largest cuttlefish prefer fish.","80 shallow seas MOLLUSCS A scallop can have 500 kg (1,100 lb) \u2013 weight of the heaviest more than 100 eyes. mollusc, a colossal squid, ever caught. GIANT PACIFIC OCTOPUS Molluscs Enteroctopus dofleini Molluscs are the most species-rich group in the ocean, Location: North Pacific making up about a quarter of all known marine animals. Total length: Over 3 m (10ft) From colossal squid to tiny sea slugs, molluscs are very diverse in size as well as habitat and habit. The largest and longest-lived species of octopus in the world, the giant All molluscs are soft-bodied, with a muscular foot, a head, and a Pacific octopus feeds mainly on fleshy mantle. Many have shells, while some species have lost crabs, snails, shrimp, scallops, their shell through evolution, enabling them to grow larger clams, and lobsters. It takes and move faster than their shelled relatives. its food back to its den to Some are filter feeders, others graze on algae eat and tosses any shells or sponges, and many are predators. outside the entrance. Mantle The mantle is a sleeve of skin that surrounds the body, which contains the internal organs. Head No match The octopus can trap small sharks such as this North Pacific spiny dogfish. Suckers Octopus arms About 280 All octopus have eight suckers line strong arms. Unlike squid each long arm. and cuttlefish, they do not have a separate pair of longer tentacles (see p.79). NEW ZEALAND QUEEN SCALLOP SEA SLUG GREEN-LIPPED MUSSEL Aequipecten opercularis Hypselodoris infucata Perna canaliculus Location: Northeast Atlantic Location: Indo-Pacific Location: New Zealand Shell length: Up to 9 cm (31\u20442in) Length: Up to 5 cm (2 in) Shell length: Up to 26 cm (101\u20444 in) The shell of the queen scallop can vary in colour. These sea slugs eat sponges but are not harmed These mussels filter microscopic algae and other They live attached to the seabed until they have by the sponges\u2019 chemical defences. Instead, they plankton out of the water for food. Before they grown to about 2 cm (3\u20444 in) in diameter, but from incorporate the toxic chemicals into their own settle permanently in place as adults, they are then on they become free-swimming. body, making themselves distasteful to predators. called spats and move about on a muscular foot. Many eyes set Gills for breathing round shell rim","85,000 The estimated number of mollusc species, 1,180 The maximum number of eggs a female bigfin reef 81 two-thirds of which live in the ocean. squid has been recorded laying in one spawning. FLAMBOYANT CUTTLEFISH Mantle PALAU NAUTILUS Metasepia pfefferi Nautilus belauensis Location: Indo-Pacific Location: Palau (N.W. Pacific) Mantle length: Up to 6 cm (23\u20448 in) Shell diameter: Up to 23 cm (9 in) Small and colourful, these cuttlefish are Like most nautilus, this species migrates to highly toxic. Perhaps because of this, shallower water at night and feeds on shrimp, fish, it is one of the few species of cuttlefish and crabs. During daylight hours, that is active during the day, hunting its they sink deeper to avoid prey of fish, crabs, and shrimp. becoming food themselves. Females are bigger than males MALE FEMALE STRIPED PYJAMA SQUID MIMIC OCTOPUS BIGFIN REEF SQUID Sepioloidea lineolata Location: Australia Thaumoctopus mimicus Sepioteuthis lessoniana Mantle length: Up to 5 cm (2 in) Location: Indo-Pacific Location: Indo-Pacific Total length: Over 48 cm (19 in) Mantle length: Up to 33 cm (13 in) A species of bobtail squid, the striped pyjama squid is small and chubby. It spends a lot of its Earning its name for its ability to mimic other Bigfin reef squid have a large fin that runs most time buried up to its eyes in sand at the bottom species, this octopus shapes itself to look like of the length of the mantle. They grow very fast of shallow seas, with arms tucked in, waiting to lionfish, sea snakes, jellyfish, flatfish (shown but live for less than a year, spending their early pounce on its favourite prey of shrimp and fish. here), and many other marine animals. days in big shoals. Like all squid, cuttlefish, and octopus, they squirt ink in self-defence. Arms drawn together TIGER COWRIE Ink jet Snail moves with its slender tip pointing forward Cypraea tigris VENUS COMB Location: Indo-Pacific Foot Shell length: Up to 15 cm (6 in) Murex pecten Location: Indo-Pacific This large omnivorous sea snail can extend the Shell length: Up to 15 cm (6 in) fleshy part of its body (the mantle) to cover its shell. It hides the mantle within its shell when Many spines protect this snail from it is threatened by predators. predators but also keep it from sinking down in the mud where it hunts for Mantle clams and other molluscs. To move, the snail uses its strong foot to raise its shell off the ground and slide away.","82 shallow seas PEACOCK MANTIS SHRIMP 460 The number of different mantis shrimp species. Amazing eyes The mantis shrimp\u2019s compound eyes are among the most complex in the animal kingdom. Each fast-flickering eye can rotate independently on its stalk. Antenna for detecting chemical Secret signals signals in the water Known as antennal scales, these paddle-like structures are used for Saddle sending visual signals that only other mantis shrimp can pick up. Club swings out from the body towards prey Club action When ready to strike, muscles inside the limb contract. This sets up tension in the part known as the \u201csaddle\u201d, just behind the club. When the tension is released, the club swings out at very high speed, like an arrow released from a bow, creating forces thousands of times that of the mantis shrimp\u2019s own body weight. Not strong enough The snail\u2019s shell cannot withstand the 154-kg (340-lb) force per strike. Tasty snail Bursting bubble Once the shell is broken, adding shock wave to punch the mantis shrimp will eat the soft body inside. Handy tools Good for gripping food, moving things, and burrowing, these front limbs are held up close to the body when not in use.","80 km\/h (50 mph) \u2013 the speed at which the 16 The number of different photoreceptors in 83 shrimp\u2019s clubs shoot out from the body. a mantis shrimp eye \u2013 humans have three. Peacock mantis crustacean shrimp PEACOCK MANTIS SHRIMP Living in tropical waters, these colourful marine crustaceans may look a bit comical with their Odontodactylus scyllarus swivelling eyes and sudden darting movements, Location: Indo-Pacific but they can throw a deadly punch. Length: 17 cm (63\u20444 in) Diet: Shrimp, crabs, clams, mussels, snails There are many different species of mantis shrimp, grouped into two types based on the shape of their \u201cweapons\u201d \u2013 a set of limbs Mantis vision at the front of their body used for killing prey. The peacock Mantis shrimp have compound eyes. These consist of thousands mantis shrimp belongs to the smashers, which have two of small units, each made up of a cornea, a lens, pigment cells, club-like limbs that strike through the tough shells and and photoreceptors. The units work together, building a very exoskeletons of their favourite foods. The other type wide-angled view of their surroundings. The range of light of mantis shrimp are the spearers, who spear fish wavelengths the mantis shrimp eye can detect, from ultraviolet and worms for their meal. Peacock mantis shrimp to near-infrared, far exceeds that of a human eye. live in burrows or in rock crevices, keeping their home tidy and sometimes disguising the Transparent cornea forms a entrance with bits of loose corals and stones. protective layer, and together with They may live for over 20 years. the lens, it refracts (bends) light Lens Smash-up dinner Pigment cells help guide the light down The peacock mantis shrimp uses the club-like to photoreceptors heels of its large second pair of limbs like hammers to break shells. When it strikes, Photoreceptor converts the club moves so quickly through the light into signals the water that some of the water vaporizes brain can process (turns into a gas), creating a bubble that then quickly bursts. This sends a shock Optic nerves carry electric wave through the shell in addition to the signals to the brain impact of the punch itself. COMPOUND EYE OF A MANTIS SHRIMP Limbs for Clubs, tucked in when not used cleaning eyes for defence or killing prey and body Swimming limbs also beat to keep water passing over the gills Front limbs A female mantis Walking Limbs used to shrimp uses her limbs swim front limbs to backwards hold her many pink eggs Legs for all occasions Mantis shrimp have lots of different limbs, known as appendages. Apart from their two clubs, they have one pair for cleaning themselves, three pairs for holding and burrowing, three pairs for walking, five pairs for swimming, and one paddle-like pair for swimming backwards.","84 shallow seas CRUSTACEANS 800,000 The number of eggs a giant tiger prawn can produce in a single spawning. Spiny antenna Carapace Like other crustaceans, the spiny Covering the head and front lobster has four antennae that act part of the body, the shield- as sensors. Two are longer than its like carapace is the largest body and covered in spines. plate of a crustacean\u2019s external skeleton. Protective spines Smaller antennae PORCELAIN CRAB Lots of legs All lobsters are Neopetrolisthes maculatus decapods, meaning Location: Indo-Pacific they have 10 legs. Carapace width: Up to 1 cm (3\u20448 in) Crustaceans Tiny and flat-bodied, porcelain crabs hide among sea anemones. The anemone\u2019s stinging tentacles Crabs, lobsters, crayfish, shrimps, prawns, krill, and barnacles protect the crab from predators and in return are among the 67,000 species of crustaceans discovered so far, the crab nips at anything threatening probably only a tiny fraction of the total number that exist. the anemone. Most crustaceans live in water, the majority in salty seas. Crustaceans belong to the same group of animals as insects \u2013 they are invertebrates (animals without a backbone) but their bodies are supported by an external skeleton. This gives them a hard protective casing, but means that they have to shed their skeleton as their body grows. Some marine crustaceans can swim, but many mostly walk on the seabed. HARLEQUIN SHRIMP GIANT TIGER PRAWN ANEMONE SHRIMP Hymenocera picta Penaeus monodon Periclimenes sagittifer Location: Indo-Pacific Location: Indo-Pacific Location: N. E. Atlantic, E. Mediterranean Length: Up to 5 cm (2 in) Length: Up to 30 cm (12 in) Length: Up to 2.5 cm (1 in) These beautiful shrimps feed almost exclusively on When they are young, these prawns live in sandy By making its home among the long, stinging starfish. Usually found living in pairs, the shrimps estuaries and mangroves, only moving into deeper tentacles of the snakelocks anemone, this little work together to turn over a starfish to get at its waters as adults. They feed on debris on the shrimp is sheltered from soft, edible underparts. predators. It is not known seafloor, occasionally taking a worm whether the shrimp offers or another crustacean. benefits to the anemone in return.","9.7 million tonnes (10.7 million tons) of crustaceans 85 are consumed by humans each year. CARIBBEAN SPINY LOBSTER FISH LOUSE ACORN BARNACLE Panulirus argus Lepeophtheirus salmonis Balanus glandula Location: Atlantic, Caribbean, Gulf of Mexico Location: Pacific, Atlantic Location: Pacific coast of N. America Length: Up to 60 cm (235\/8 in) Length: Up to 1cm (3\u20448 in) Diameter: Up to 2 cm (3\u20444 in) Unlike some lobsters, spiny lobsters lack large This parasite is usually found on salmon. This species is found in large claws. They feed on snails and small molluscs called The fish louse attaches itself to the numbers in the upper and chitons, and will also eat dead animals they find on fish, feeding on its mucus, skin, and middle shore level. Like the ocean floor. Females carry their eggs on the blood. Fish lice are found in natural other barnacles, when underside of their abdomen. When the larvae hatch, conditions, but they breed faster covered by water it filter they swim freely for about a year before settling in in salmon farms, where they feeds using its hairlike seagrass beds. As adults, each autumn they march can rapidly spread out cirri. At low tide, the cirri in single file towards deeper waters to spawn. of control. retract inside the shell. Made for walking Body Closed in Cirri The jointed legs are used for Layers of walking on the seabed. Future generation chalky shell This female fish louse protect the is carrying her eggs in soft body two long strings. inside. SHAME-FACED CRAB BRISTLED SPONGE CRAB COMMON LOBSTER Calappa calappa Austrodromidia octodentata Homarus gammarus Location: Indo-Pacific Location: Southern Australasia Location: East Atlantic, Carapace width: Up to 15 cm (6 in) Carapace width: Up to 8 cm (31\u20448 in) Mediterranean, Black Sea Named for the way its claws fold up to cover Like all its sponge crab relatives, this bristly Length: Up to 65 cm (255\u20448 in) its face, this crab can burrow quickly to avoid species uses sponges as protective camouflage. predators. It specializes in feeding on molluscs It carries the sponge on its back, holding it in These large lobsters prefer to live on rocky such as clams, using the pincers at the end of its place with its rearmost pair of legs. seafloors, spending their days hiding in little claws to prise open or break their shells. caves or crevices. They emerge at night to feed on invertebrates such as crabs, molluscs, sea urchins, and starfish. JAPANESE SPIDER CRAB DECORATOR CRAB Macrocheira kaempferi Camposcia retusa Location: Coasts of Japan and Taiwan Location: Indo-Pacific Carapace width: Up to 40 cm (153\u20444 in) Carapace width: Up to 3 cm (11\/4 in) If its long legs are added to its carapace width, this crab can reach an impressive total width of Decorator crabs fool 3.7 m (12 ft). Japanese spider crabs are rarely their enemies by found at depths of less than 50 m (165 ft). camouflaging themselves with items from their All dressed up surrounding Even the legs are environment. covered as part of this They snip off crab\u2019s disguise. tiny scraps of algae, sponges, and even anemones, and attach them to their shell and limbs. The small bristles on a decorator crab\u2019s body hold the disguise in place.","","Horseshoe crab Having changed little in over 400 million years, horseshoe crabs are like \u201cliving fossils\u201d. They are more related to spiders than true crabs. Horseshoe crabs spend most of their life walking along the sandy ocean floor, eating worms and molluscs. But during the breeding season, they head for beaches where the females lay their eggs. They have a unique swimming style, moving upside down and at an angle using their long tail as a rudder, like this horseshoe crab in the Pacific Ocean. This reveals body parts normally hidden beneath its helmet-like shell, such as the waving jointed legs and the gill flaps that help it swim.","88 shallow seas FLOWERY FLOUNDER Colourful pigment spots only appear on one side \u2013 the side facing the seabed is plain white. 1 Young flounder larva Dorsal fin Only about 5 mm (3\u204416 in) long, this young 2 Transformation flowery flounder larva has an eye on each side Soon the right eye starts to of its head and swims upright. Long fin rays migrate. The larva has now begun help make it appear larger to predators but swimming at a tilt, with more of its these will soon fall off. left side angled up to the sky. The tilt angle increases steadily. Temporary ray fin Eye on the move Anal fin Tissue underneath the right eye starts Signs of pigmentation to grow more cells, The skin on the left side gradually pushing of the body begins to get some colour. this eye up and across the head. Right eye is on the right See-through body side of the body There is no pigmentation in the skin yet and the body is transparent. Flatfish eye migration Swimming angle At this stage, the In just a few days, the larvae (tiny baby flounders) change flounder swims at an from looking like normal fish, with one eye on each side of angle of around 20\u00b0. their head, to develop the asymmetrical features typical of all flatfish. During this metamorphosis, known as eye migration, the skull bones of the fish are still relatively soft and pliable, and shift to let one eye migrate from one side of the skull to the other. Swimming style Spot the flounder Although flowery flounders typically \u201ccrawl\u201d along the Like all flounders, flowery flounders can quickly change bottom using the dorsal and anal fins that line their body, colour to match their background. This helps them hide from they also swim when needed. They undulate their body predators, as well as approach prey of their own without being and use their dorsal, anal, and tail fins for propulsion. seen. They also bury themselves in sand for extra camouflage, They never stray far from the bottom while swimming. totally blending in with the seabed.","2\u20138 seconds \u2013 the time it takes for If a flounder gets sand in one eye, it briefly loses its ability to camouflage 89 a flounder to change colour. itself since it needs to see its surroundings to colour match them. Pectoral fin Tail, or caudal fin 3 Adult flounder Often raised for a sudden take-off, Once eye migration is complete, juvenile flowery flounders settle flat on the bottom, but they are still the long pectoral fin is folded flat only about 35 mm (13\u20448 in) long. They don\u2019t become down when not needed. large mature adults, like the one shown here, for around one year. By then they will have grown to Dorsal fin 10 times the size, and still continue to grow. The dorsal (back) fin ends up on one side, flat on the seabed. Anal fin Opposite the dorsal fin, the anal fin now also sits along one side of the body. Flowery flounder Eyes on stalks Multitasking fins Positioned on short, Propelling the flounder Part of the large flatfish family, flowery flounders belong thick stalks, the flounder\u2019s when it swims, these to a group known as left-eyed flounders. This is because, eyes can each rotate 180\u00b0 fins can also be used for as adults, both their eyes sit on what looks like their back independently of one \u201cwalking\u201d on the seafloor. but actually is the left side of their flat body. another. This gives the fish a very large field of vision. Spots of colour These fish are not born this way but transform in an astonishing The adult flowery flounder process known as eye migration. At the same time, they also can make its blue spots become bottom-dwelling as they settle sideways on the seabed. look very bright. Flounders spend most of their time partially hidden in the sand, with only their swivelling eyes sticking out and scanning for prey. fish FLOWERY FLOUNDER Bothus mancus Location: Tropical Indo-Pacific, east Pacific Length: Up to 51 cm (20 in) Diet: Small fish, crabs, shrimp","90 shallow seas SEABED FISH 6 m (192\u20443 ft) \u2013 the length of a European conger reeled in off the coast of the UK, the biggest conger eel caught to date. Seabed fish LEAFY SEADRAGON Fish that live near or on the seabed are known as demersal fish. They are divided into two groups \u2013 Phycodurus eques those that spend most of their time lying right on Location: Southern Australia the bottom and those that swim just above it. Length: Up to 35 cm (133\u20444 in) Bottom dwellers come in all different shapes and sizes, The leafy seadragon belongs to the same family as and can be found anywhere from shallow waters to the seahorse. It has a slender, pipe-like mouth that the deeper ocean. Many have flat bodies that allow it uses to suck up tiny organisms. The seadragon\u2019s them to lie on the bottom, while others bury themselves brownish-green, leaf-like body parts make it hard deep in the sand, with only their eyes uncovered to spot among seaweed and kelp. Females lay their to watch for passing predators and prey. Those eggs under the tail of the males, who carry them with upturned mouths can grab prey as it until they hatch. swims by, while a downturned Spines for mouth is useful defence for digging things out of the seabed. Camouflage Toothless Semi-transparent snout lobes of skin look like seaweed. SPOTTED GARDEN EEL ANGLER FISH MANYTOOTH CONGER EEL Heteroconger hassi Lophius piscatorius Conger triporiceps Location: Tropical and sub-tropical Indo-Pacific Location: Northeast Atlantic, Location: Tropical western Atlantic Length: Up to 40 cm (153\u20444 in) Length: Up to 80 cm (311\u20442 in) Mediterranean Sea Living in big groups, the Length: Up to 100 cm (40 in) The manytooth conger eel is commonly found spotted garden eel sits in its searching out prey around rocky seafloors or coral burrow with a third of its body The spines on the angler fish\u2019s head have evolved reefs near islands. After hatching, it can spend up poking out, facing the current into \u201clures\u201d. The angler fish lies on the seabed, half to a year as a tiny, transparent, flat larva that looks and catching food as it drifts by. buried in mud or sand, waving its lures about to nothing like an adult conger. When threatened, it quickly make it look like small wiggling fish. Any fish withdraws inside. coming in to investigate becomes a meal itself. Several fins are merged together, Lure forming one continuous fin","50 years \u2013 the maximum recorded 117 km (73 miles) \u2013 the distance that a 91 age of an Atlantic halibut. thornback skate can migrate in a month. The body is STRIATED FROGFISH covered with bony plates Antennarius striatus instead of scales Location: Tropical ALLIGATOR PIPEFISH and subtropical oceans Length: Up to Syngnathoides biaculeatus 10 cm (4 in) Location: Indo-Pacific Length: Up to 29 cm (113\u20448 in) Specially evolved leg-like fins allow this bottom Found in colours from yellowish green to brown, dweller to \u201cwalk\u201d along the thin, grass-shaped alligator pipefish blends in the ocean floor. Snatching among seagrass or seaweed. To look even more prey in ferociously fast grass-like, it spends a lot of time in a near vertical movements, the frogfish position with its head pointing down. A poor stretches its mouth so swimmer, it uses its flexible tail to anchor itself much that it can swallow to the vegetation so as not to get swept away fish the same size by strong currents. as itself. Fins used for walking ATLANTIC COD SPLENDID TOADFISH ATLANTIC STARGAZER Gadus morhua Sanopus splendidus Uranoscopus scaber Location: North Atlantic, Arctic Location: Cozumel Island, Mexico Location: Northeast Atlantic, Length: Up to 1 m (31\u20444 ft) Length: Up to 24 cm (91\u20442 in) Mediterranean Sea The Atlantic cod spends its days in schools This brightly coloured member of the toadfish Length: Up to 22 cm (85\u20448 in) swimming about 30\u201380 m (98\u2013262 ft) above family feeds on fish, snails, and marine worms. the sea bottom. However, as it gets dark, these It is often found lurking beneath coral outcrops Like other fish in the stargazer family, the Atlantic groups break up and individuals swim down to or near rocky caves, with only stargazer has eyes on the top of its head that are feed on invertebrates and smaller fish that its mouth sticking out. pointed skywards. It is well adapted for lying live on the seabed \u2013 including juveniles buried on the seafloor with only its eyes exposed. of their own species. It has a special organ that can generate sound and electric pulses, used for defence and communication. ATLANTIC HALIBUT THORNBACK SKATE ROCKSUCKER CLINGFISH Hippoglossus hippoglossus Raja clavata Chorisochismus dentex Location: North Atlantic Location: Eastern Atlantic, southwest Location: Southeast Atlantic Length: Up to 4.7 m (151\u20442 ft) Length: Up to 30 cm (12 in) Indian Ocean, Mediterranean Sea Endangered due to overfishing, the Atlantic halibut Length: Up to 85 cm (331\u20442 in) The rocksucker lives in very shallow waters, is the largest flatfish in the world. The maximum even within the intertidal zone. It can cling reported weight is 320 kg (705 lb). When it is small, A ridge of enamel-covered, thorn-shaped denticles to rocks with fins that work like sucker it eats mostly invertebrates, switching to a more (see p.92) runs along the back of the thornback pads, and uses its large fang-like fish-based diet as it grows. skate. Females even have a thorny underside. teeth to pick off the limpets Young skates stick near to shore while adults that are also head to deeper waters, coming sticking to into shallower water only the rocks. in spring and summer.","92 shallow seas GREAT HAMMERHEAD 580 kg (1,280 lb) \u2013 the weight of a large adult great hammerhead. Great hammerhead Dorsal fin This large fin helps stop the Largest of the nine different species of hammerhead sharks, the great hammerhead has a wide, straight \u201chammer\u201d and a tall dorsal shark from rolling side fin. Formidable hunters and swimmers, these sharks make long to side but also helps it make sharp turns. seasonal migrations, moving from warm waters to cooler ones during the summer months. Shark skin A close-up of shark skin reveals The great hammerhead shark is a critically endangered species, tough, V-shaped scales. Called dermal having long been targeted for its dorsal fin, which is used for denticles, these are structured in the shark fin soup and as medicine in some countries. Because same way as teeth and covered by hammerheads are slow to reproduce \u2013 females carry their a layer of enamel. This helps reduce young for 11 months, and only breed once every two years drag and turbulence. \u2013 it is hard for the species to recover from overfishing. Tailfin Superb swimmer A second dorsal fin This is the shark\u2019s stabilizes the back propeller, moving A hammerhead is always on the move \u2013 if end of the shark side to side to push it stops swimming it suffocates, as water the shark forwards. does not flow over its gills if it stays Hammerhead tailfins still. Its light skeleton and body shape have two unevenly make it a very efficient and fast sized lobes, the upper swimmer. To turn, it changes the one always larger angles of its fins to alter the than the lower one. flow of water over its body. Locating prey Brain Pelvic fin Countershading A pair of pelvic fins The shark\u2019s pale When hunting, great hammerheads Cephalofoil help the shark turn, underside makes it swim near the seabed, making less visible against broad back and forth movements Electrical sensors roll, and move up the sunlit surface, with their head, as though they measure a change and down. and hard for fish or are scanning the ocean floor. This other prey to spot is because in addition to sight and in voltage in when it approaches smell, they have tiny electrical the water sensors on their cephalofoil. These from above. detect the electric impulses of their prey, helping the shark to find food hiding in the sand. Stingray hidden in the sand Electric field formed by pulses produced by the stingray\u2019s muscles","3,000 km (1,864 miles) \u2013 the distance great 30,000 The number of teeth a shark 93 hammerheads migrate in a year. can get through in a lifetime. Nostril Electrical sensors Handy hammer Eye Water flows in through the A network of jelly-filled pores, The broad, flattened hammer-shaped called ampullae of Lorenzini, lies head is known as a cephalofoil. nostrils, where sensory cells detect along the hammer. The pores Supported by a wide cartilaginous chemicals in the water, such as help sharks detect electric fields, skull, it contains key sensory organs. those associated with blood. such as those generated by fish moving in the water. Smell detector Behind each nostril is a large sac full of sensory cells that pick up different smells. This gives hammerheads an extremely good sense of smell. Skull Nostril Optic nerve The optic nerve connects the eye to the brain. In hammerheads, it may be up to 30 cm (12 in) long. Eye The position of the eye at the end of the head enables the hammerhead to see 360\u00b0 in all directions \u2013 above, below, behind, and in front. Cartilaginous skeleton LOWER JAW OF GREAT HAMMERHEAD SHARK Cartilage is a rubbery tissue that is lighter and more flexible than bone. Tooth about New tooth Tooth forming to be shed in groove Gill slits Lower jaw To breathe, hammerheads take in cartilage water through their mouth as they swim. This water flows over the gills Bright new teeth in their mouth and then out again Unlike human teeth, shark teeth don\u2019t have roots through the gill slits in the skin. and are not embedded in the jaw, but sit in soft tissue and are replaced constantly. As new teeth fish form inside a groove in the gum and are pushed out, as on a conveyor belt, old teeth fall out. GREAT HAMMERHEAD Pectoral fin Sphyrna mokarran These large fins act like wings of a plane. Location: Warm temperate and tropical waters When angled up, they generate lift as the Length: Up to 6 m (192\u20443 ft) shark swims forwards. Diet: Rays, invertebrates, fish, sharks","94 shallow seas SHARKS 100 million sharks are killed each year by humans, while only about six humans are killed by sharks. Sharks TIGER SHARK There are more than 500 shark species \u2013 the smallest is as long as a pencil, the largest is longer Galeocerdo cuvier than a city bus. They all have a skeleton made of a Location: Warm waters worldwide springy material called cartilage, rather than hard Length: Over 5.5 m (18 ft) bone, and all have an acute sense of smell. The distinctive dark stripes that give Sharks are as varied in their habits as they are in size the tiger shark its name are far more and appearance. Many spend nearly all of their time in prominent in younger animals, and fade shallow waters, cruising coastlines or coral reefs. Others with age. Tiger sharks eat a huge variety live in deeper waters, only visiting warmer shallow seas of food, from sea snakes and squid to in winter or to take advantage of seasonal food sources seals and dolphins. such as seal pups or migrating fish. Some sharks are swift and skilled predators, while others feed on microscopic organisms that they filter from the water, or munch on hard-shelled molluscs that live on the seafloor. BLACKTIP REEF SHARK BASKING SHARK Carcharhinus melanopterus Cetorhinus maximus Location: Indo-Pacific Location: Worldwide Length: Up to 2 m (61\u20442 ft) Length: Over 10 m (33 ft) This is one of the most common shark species With its gigantic mouth gaping wide, to be found around shallow coral reefs. Blacktips the filter-feeding basking shark swims tend not to roam far, preferring to stay in the same slowly at the surface, taking in water and area for several years. They typically eat molluscs trapping plankton, including fish larvae such as squid and octopus, fish, and crustaceans. and other tiny prey. These minute organisms are caught by bristles called gill rakers. BULL SHARK Carcharhinus leucas Location: Warm coastal waters Length: Up to 3.4 m (111\u20446 ft) Found in shallow coastal areas, bull sharks are unique in being able to thrive in both salt and fresh water and have been known to swim far up rivers. They eat a wide variety of animals. TAWNY NURSE SHARK Tawny nurse sharks spend their days piled Spines sit at the on top of each other inside sea caves or under front of each Nebrius ferrugineus rocky ledges. At night, they emerge to feed dorsal fin Location: Indo-Pacific by sucking out octopus, sea snakes, fish, and Length: Up to 3.2 m (101\u20442 ft) invertebrates from their burrows and crevices. HORN SHARK Heterodontus francisci Location: Pacific coast of N. America Length: Up to 1 m (3 1\u20444 ft) This nocturnal hunter feeds on molluscs, starfish and urchins, and crustaceans. The horn shark has a powerful bite that cracks through the shells of its prey. Relatively small and slow-moving for a shark, this species has large spines on its dorsal (back) fins for defence.","70 years \u2013 the possible lifespan 513 The approximate number of 450 tonnes (500 tons) \u2013 the amount of water a 95 of a male great white shark. shark species discovered so far. basking shark filters through its gills every hour. Seal prey COOKIECUTTER SHARK ANGEL SHARK GREAT WHITE SHARK Isistius brasiliensis Squatina dumeril Location: Warm waters worldwide Location: Eastern USA, Caribbean Carcharodon carcharias Length: Up to 56 cm (22 in) Length: Up to 1.5 m (5 ft) Location: Worldwide Length: Up to 6 m (195\u20448 ft) This little shark is a parasite. Sometimes mistaken for a ray or skate because It uses its uniquely shaped of its flattened body, the angel shark often lies Great whites live in coastal and mouth like a pastry cutter buried on the seafloor, waiting to snatch passing offshore waters all round the to bite out pieces of flesh fish or squid. It lives in shallow seas in summer world and can tolerate a range from other fish and marine and autumn, then moving to deeper water for of temperatures from 5\u00b0C to mammals without intending winter and spring. 25\u00b0C (41\u201377\u00b0F). Females to kill them. It feeds at dusk, are usually larger than males. Unlike many moving up from the deeper sharks, great whites ocean to near the surface. regularly lift their head above water and have COMMON SAWSHARK been seen taking birds from the surface. Pristiophorus cirratus Location: Southern Australia Length: Up to 1.5 m (5 ft) Also known as the longnose sawshark, this species has a long snout ringed with sharp teeth and often swims in large groups. It feeds on small fish and crustaceans, using the whisker-like barbels on its snout to detect prey, and its sharp teeth to slash at its victims. Barbels contain taste buds for sensing prey CHAIN CATSHARK WHITESPOTTED BAMBOO SHARK Scyliorhinus retifer Chiloscyllium plagiosum Location: Northeast Atlantic Ocean, Location: Japan, Southeast Asia Length: Up to 95 cm (373\u20448 in) Gulf of Mexico, Caribbean Sea Length: Up to 59 cm (231\u20444 in) This nocturnal shark feeds on fish, small crabs, and shrimp around shallow coral reefs. Preyed on The beautifully marked chain catshark spends its by larger sharks, it has a narrow enough body to days resting on the seabed, but becomes active at take refuge in small crevices. Bamboo sharks are night to feed on squid, fish, and crustaceans. This often captured as aquarium pets, which may species is biofluorescent \u2013 it absorbs the blue eventually threaten their numbers. light of the ocean, making its skin glow green.","96 shallow seas SARDINE RUN 7 km (4 1\/4 miles) \u2013 the estimated length of some of the larger shoals off South Africa\u2019s coast. Sardine run Jackass penguin Most winters, a spectacular event takes place off Penguins are fast, agile the coast of South Africa. This is the sardine run, swimmers but must when millions of migrating sardines attract lots beware of becoming prey of hungry predators in a frenzied feast. themselves for fur seals and sharks. Fish often form groups, called shoals. Sometimes, a shoal swims in close formation, synchronizing every move. This behaviour, known as schooling, is used when fish migrate or to deter predators. Sardine runs occur in many places across the world, but the South African shoals are among the largest, although the number and sizes vary from year to year. Baitball break-up Large shoals of migrating sardines quickly attract the attention of predators. When the sardines sense predators nearby, their response is to confuse them by swimming closer together, packing themselves into tight spheres called baitballs. Common dolphins are usually the first at the scene, working to push the sardines closer together and up towards the surface, leaving them no place to go. Soon other predators come to take part, both from the surrounding sea and the air above. As they attack, the baitball breaks up. Going with the cold flow Cape fur seal Hunting in small groups, fur Sardines prefer lower temperatures, and in summer they are seals swim straight through restricted to cool waters off South Africa and in the chilly the baitball, snatching at prey. Benguela current to the west. In winter, coastal seas up the eastern coast get cold enough for the sardines to migrate Baitball further north to spawn \u2013 something they do in their millions. This formation confuses Afterwards, they probably return south in the deeper, cooler predators\u2019 senses and makes waters beneath the warm Agulhas current. it harder for them to AFRICA single out individual prey. Sardine run route Bronze whaler shark In winter, shoals start These sharks work with each other to herd swimming northeast along the coast, following a prey fish closely together, and then take corridor of cool water turns swimming through the baitball to grab any fish they can. close to the shore. ATLANTIC SOUTH OCEAN AFRICA INDIAN OCEAN Benguela Agulhas current current Key Summer season In summer, sardines stick to cooler southern waters, but can reach further northwest by following the cold Benguela current. Cold current Movement of sardines Warm current Sardines","97 Long-beaked Cape gannet common dolphin Hitting the water at speeds Pods of dolphins follow the approaching 120 km\/h shoals, cleverly herding (75 mph), this large seabird sardines together in an ever dives straight into the tighter group before baitball, then swims snatching their share. back up towards the surface, swallowing its Sardine catch on the way. There are many species of fish commonly referred to as sardines or Breaking up the ball pilchards. The Southern African pilchard Predators such as sharks can be up to 30 cm (12 in) long. have their best chance of seizing prey when they can break up a baitball into smaller groups. Lateral line The lateral line Fish have good vision, but they need additional senses to help them keep very close without crashing into each other when they move in a school. All fish have a lateral line, which is a system of sensory channels running around the head and along the body. The channels have highly sensitive hair cells that detect tiny changes in water currents to help the fish coordinate their movements.","98 shallow seas CORAL REEF Coral reefs only make up around 1 per cent of the ocean floor but are home to 25 per cent of ocean species. Coral reef Polyp So large they are visible from space, coral reefs are built up over Skeleton thousands of years by living, growing corals. Hotspots of marine life, reefs also protect coastlines from tropical storm waves. Connecting tissue Corals, consisting of many connected tiny coral polyps, are invertebrate animals and most need sunlight to stay healthy. Together with sponges and Coral colony other reef-forming organisms they provide a habitat for other living things. Corals are large groups of tiny animals Their structure creates perfect habitats for algae and tiny invertebrates. These called polyps living together, connected by attract an abundance of different species coming here to feed, each adding living tissue. The polyps secrete a mineral their own colours, shapes, sounds, and visual displays to the vibrant scene. called calcium carbonate, forming the hard skeleton that gives the colony its shape. Day and night on the reef Longnose butterfly fish These fish chase away During the day, the reef is busy with any intruders from many kinds of colourful fish. They spend their patch of coral. their time grazing and protecting their territory. Beneath ledges and in crevices, DAY-TIME REEF nocturnal fish can be found resting. At night, most herbivores seek shelter and Parrotfish more carnivorous fish come out to hunt. This parrotfish feeds on Night time is also when most corals open corals and the algae living their polyps to feed. inside them. Regal angelfish This angelfish likes to feed on sponges: simple, animals that look like plants and are attached to the reef bed. Chromis These small fish school above the coral to feed on plankton. Sea fan Sea fans are soft corals. They don\u2019t produce a hard calcium carbonate skeleton. Brain coral Shark hideout Sea slug Tube The round shape Whitetip reef sharks Often poisonous, sea sponge and curly grooves slugs cruise the reef of this sturdy coral spend their days munching on sponges. Yellow tang make it look a bit resting in caves and The bright yellow is a day-time colour \u2013 at night like a brain. It under reef ledges. it fades while a prominent doesn\u2019t feed during white stripe develops. the day, so keeps its tentacles retracted until night time.","33 per cent of the world\u2019s coral reefs 1,000 The approximate number of hard coral species around the 99 are in Australia and Indonesia. world, supporting more than 4,000 species of fish. Whitetip reef NIGHT-TIME REEF Squirrelfish sharks on the hunt Hidden during the day, squirrelfish come out These nocturnal at night to feed on predators hunt in crabs and shrimp. groups, seeking out fish hiding in coral crevices. Soldierfish Large eyes help these fish see in low light as they cruise above the reef to catch tiny crustaceans in the plankton floating by. Filter-feeding brain coral with open polyps Moray eel Sleeping parrotfish Coral feeding time Moray eels hunt The parrotfish Like most corals, the black sun coral at night, smelling covers itself in a feeds at night. Its polyps open to protective bubble extend their delicate stinging tentacles out their prey. of mucus that helps to capture plankton that floats by. mask its scent. Sea urchin With venomous spines as defence, sea urchins crawl out across the reef to graze on algae. Coral polyp Tentacle Mouth Coral bleaching Each polyp on a coral is Living tissue Microscopic algae called connecting to zooxanthellae live within an individual organism. other polyps the coral\u2019s tissues, helping to feed the coral by using Its tentacles, only visible Base sunlight\u2019s energy to make food. If water when the polyp is open, temperatures rise as little as 1\u00b0C (1.8\u00b0F) contain special stinging Stomach above average, the cells to immobilize its coral may expel the algae. This leads to bleaching. prey \u2013 plankton and small Unless more algae move in within a short period fish. The tentacles transfer Corallite of time, the coral may die, leaving only a pale skeleton. the food to the central mouth. Each soft polyp sits within its own casing, a tiny part of the skeleton called corallite. As polyps grow, they add more minerals to the coral\u2019s skeleton, making it grow thicker.","100 shallow seas CLEANER WRASSE 1,218 The recorded number of parasites a single cleaner wrasse can eat in a day. Cleaning stations Useful relationship Cleaning stations are areas, often on reefs, This tomato grouper benefits from having where aquatic animals know they can come to parasites and dead tissue picked from its body. get cleaned of parasites, algae, and dead tissue In return, the wrasse get a good meal. Once the by other animals. Animals that come to these grouper has gained the attention of this cleaning stations are known as \u201cclients\u201d. crew, it assumes a relaxed position that shows the cleaners that it is safe to start work. Each client species has its own relaxed pose. fish BLUESTREAK CLEANER WRASSE Labroides dimidiatus Location: Indian and Pacific oceans Length: Up to 14 cm (51\u20442 in) Diet: Crustacean parasites, dead skin, mucus Queuing up Cleaner wrasse Clients will queue at cleaning stations. While they do, they watch the cleaners at work. If the cleaner-fish Cleaner wrasse earn their name from their unusual feeding cheats and takes a nip of the client, those in the queue behaviour. Working together in groups called \u201cunits\u201d, these might decide to go elsewhere. Here a green sea turtle fish are specialists in picking off and eating parasites, waits for yellow tang to finish off the client in front. dead skin, and mucus from other fish. A unit can consist of one male accompanied by several females, of one male and one female, or of juveniles only. All cleaner wrasse are born female. When a male dies, the largest female will turn into a male and take his place. If a male loses all the females in his unit, he will pair with the first cleaner wrasse he finds, including another male. If this happens, the less dominant male of the pair will turn back into a female. Cleaner wrasse spend their whole life on coral reef cleaning stations in shallow tropical coastal waters. Cleaner shrimp Fish aren\u2019t the only group of cleaners in the ocean. There are also species of shrimp that specialize in removing parasites from clients such as this moray eel. Cleaner shrimp are often found at coral reef cleaner stations, sometimes even alongside cleaner wrasse. Greeting Protractile jaws Cleaner wrasse greet their The mouths of cleaner potential clients with dance-like wrasse extend out letting behaviour that involves bouncing them grab parasites, as if their tail up and down, especially with a pair of tweezers, when the client is new, or the then drawing them into cleaner wrasse is a juvenile and the mouth. so more likely to be eaten. Recognizable uniform At a distance, clients recognize adult cleaner wrasse by the prominent black stripe down each side."]