The Drama of Ocean Predators and Prey

Two-thirds of the earth is covered by water, teeming with life in many different realms. From the depths of the open ocean to the coral reefs, predators and prey fight it out in the endless struggle to survive. In this world beneath the waves, each encounter could be their last. Coral reefs are home to a vast colorful variety of creatures, all busy searching for their next meal. This is one of the richest ecosystems on the planet, and nothing here goes to waste. Everything is recycled as food or shelter. For soft corals, life is easy. All they have to do is catch the microscopic morsels drifting down from the waters above. Butterfly fish graze on hard corals and find a home among the branches. The coral garden offers some protection from the eyes of predators. For the smaller reef fish, danger is never far away. Venturing into the open is a calculated risk. The blue-spotted jawfish is safe in its burrow on the sea bottom. Once out in the open, it's vulnerable. Nearby, a predator in camouflage, a scorpionfish. The jawfish sticks close to the floor. Amid the rubble, the killer lies in ambush. A narrow escape, and the jawfish is taking no more chances. It hastily digs a new burrow. Another master of disguise emerges to look for food. The reef octopus. The scorpionfish is back in ambush mode, and the octopus's camouflage isn't so effective on the move. It's not the scorpionfish's lucky day. Its second target is just too big to swallow. The octopus isn't out of danger yet. In its panic, it's released scents into the water, and another of the ocean's smartest predators can smell fear. White with alarm, the octopus comes face to face with a two-meter moray eel. Another brush with death, and this time the octopus leaves one of its eight tentacles behind. The missing limb will soon grow again. For now, its owner makes off on the remaining seven. Meanwhile, a ghost shrimp leaves its hole, aiming for the safety of the reef. But it's entering danger zone. The octopus has returned to its den and set a trap of its own. The shrimp's soft flesh is quickly consumed, and its empty shell discarded. Some shrimps are better prepared, however. The mantis shrimp is famous for its sharp eyesight, and that's not all. Its front claws pack quite a punch, and when they're not needed for combat, they can be used as cutlery. Mussels are one of the mantis shrimp's favorite foods. Back in the comfort of its den, it cracks open the shell and scrapes out the flesh. But its meal is about to be rudely interrupted. The octopus is returning. The mantis shrimp waves its mighty claws to try and scare the intruder away. When that doesn't work, it tries a more approach. It punches the octopus in the eye. It's the octopus's weak spot. After the third blow, the octopus gives up. And it's now safe to go home. Crustaceans, like shrimps and this cancer crab, have an armored shell as well as claws, so they can afford to take a chance in the open. A female cancer crab looking for a different kind of encounter. Here's a likely candidate, big and strong, and he's definitely interested. The male revolves his partner until she's facing him. That way, the pair have all-round protection while they concentrate on each other. They may hold this armored embrace for up to two weeks before they finally mate. Some creatures live their whole lives on one spot, barnacles. They stay firmly attached to the rocks or reef, while bits of food fall straight into their tiny arms. Barnacles have no problem collecting food, but being so immobile is a disadvantage when they come to reproduce. Like these corals, all they can do is cast their eggs and sperm into the current. Other youngsters have a much more secure start in life. A newborn horn shark was also left on the reef as an egg, but it developed undisturbed inside this sturdy capsule. Now it's almost ready for the outside world. The inexperienced are always vulnerable, and danger comes in many forms. An angel shark lurks beneath the sand. The hunter swallows its victim whole and spits it out again. Even at only a few hours old, the horn shark has a secret weapon. Its horn. This tiny dagger pierced the angel's mouth and saved its life. Its cover blown, the angel shark must find a new place to conceal itself. It shuffles into a good position, ready for another unwary passerby. This older horn shark has made it through the critical first few days, and leaves the reef to mingle with creatures of the open waters. Although all alone, its telltale shape and spine deter most predators, including curious sea lions. In deeper waters, ocean inhabitants grow much larger, but many, including reef sharks, still prey on the reef community. In this twilight zone, close to the sea bottom, sharks have been the top predators for millions of years. They too rely on an element of surprise, but they use stealth rather than speed. Their tactic is the open water version of ambush, to sneak up from behind. Reef sharks aren't the fastest fish in the sea, but neither are their targets. Smaller fish can always flee to the nooks and crannies of the reef. Away from the reef, there are few hiding places, and both hunters and the hunted are built for speed. Like other open ocean or pelagic fish, the blue shark has a slender streamlined body. Three meters long, it travels thousands of kilometers, further than any other shark. This is the ultimate predator. Tiny pits detect vibrations in the water, while other sensors track its prey's electrical field. It can smell the faintest hint of blood, and its superb eyesight is protected by a special lid. Once a mackerel has been separated from the school, there's nowhere to run. Perhaps the shark's most vital assets are its teeth, which are constantly replaced. Up to six sets grow at any one time, on a kind of conveyor belt. When a tooth is lost, another simply rolls into position. While sharks are solitary predators, their rivals often hunt in packs. Barracuda. These two meter long torpedoes are a match for anything, including man. When barracuda congregate, it's obvious where their fearsome reputation goes before them. Like sharks, they can pick up the smallest vibrations, and they share the shark's position at the top of the food chain. Even on its own, a barracuda is a fearsome sight, especially when it's looking for a meal. It has vice-like jaws, and teeth as sharp as needles. A lone fish is making vibrations. The barracuda's lightning strike in slow motion. Speed and aggression are not the only secrets of survival in the open ocean. This is the world's largest fish, but it moves slowly, and is completely harmless. Weighing up to 20 tons, it may grow even longer than the humpback whale, and fully deserves its name, the whale shark. Like most of the great whales, the whale shark feeds on some of the ocean's smallest creatures. It trawls the water for tiny fish and crustaceans, known as krill. It filters enormous volumes of water through the gills, trapping tiny prey inside the huge mouth. The seas are full of surprises, and appearances are often deceptive. Like the whale shark, the wolf eel is alarming face to face, but it's one of the least aggressive creatures in the ocean. It's actually a kind of blenny, but with a huge head and two meter tail, it looks more like an eel. It even lurks in a cave like an eel. When it emerges to hunt, it's not interested in other fish. Its favorite food is more of a sitting target, found among the rocks and corals of the reef. This bizarre monster with its massive jaws preys on sea urchins. Sea urchins have no eyes, so the wolf eel doesn't need camouflage. But other reef inhabitants depend on it. Even fish of the same species may have individual markings. No two red Irish lordfish look the same. Blending so well into the coral mosaic, perhaps it's no surprise they're ambush predators. And this is just what they're waiting for. The crab isn't beaten yet. It throws out its legs and claws to make itself as large and unmanageable as possible. But not quite large enough. It manages to hang on to the lord's lips, but there's no way out. On the reef, every living thing must be able to defend itself. Even those that can't move are armed with the tools they need to survive. Tube anemones wave their tentacles, catching food to drop into their funnel mouths. They may look helpless, but their bright colours warn predators that they sting. The problem is, there's always something that can get past the security system. This is the tube anemone's worst nightmare. The rainbow nudibranch. The nudibranch is a kind of sea slug. Almost blind, it hunts by smell alone, plopping into position next to its target. Then it launches a surprise attack. The anemone tries to retreat into its tube, but the nudibranch dives in face first, gorging itself. And the sea slug steals more than a meal. It also steals the anemone's defences. The stinging cells pass through the body undigested, ending up in its own skin tissues. The nudibranch's gaudy colours attract attention, but they also advertise the fact that they don't make a good meal. Sea lions get the message and leave well alone. Nudibranchs store their stolen venom in colourful gills attached outside the body. The colours deter most predators, but not other sea slugs. They're immune to the poison. This is a sea tiger, a sea slug with an unusual taste for other sea slugs, and a novel way of catching them. It isn't always quick enough, and this one just tastes bad. When two sea tigers meet, at least it's an equal match. But some things are more important than fighting. After a quick showdown, they immediately start to mate. Each animal has both male and female organs, and during this encounter, they exchange eggs as well as sperm. It's a good solution. Being both mother and father is often easier than tracking down the opposite sex on the vast expanses of the ocean floor. But some creatures just have to make that dangerous journey from time to time. The coral crab's shell offers some protection, but the flesh inside is tempting, especially to a triggerfish. Triggerfish have strong teeth, but only a small mouth. They attack by persistent nipping. The crab uses its flat shell as a shield, which can't get a grip. It manages to ward off the attack long enough to run for cover. Crabs have many enemies, and here's another. A visitor from the ocean surface, descending to look for food. The loggerhead turtle hunts on the reef and seabottom, where crabs live. Once spotted, the crab may be able to outrun its pursuer. But if those powerful jaws get a hold, it won't stand a chance. The crab seems to have run out of steam, and death is swift. But the loggerhead has experience on its side. It may have been hunting here for decades. At night, many members of the reef community are asleep, even if their eyes are open. The reef itself never sleeps. Corals continue feeding. And nocturnal predators are also wide awake. The lionfish is a close relative of the scorpionfish, with venomous spines. It spreads giant fins to make a kind of net, cornering sleepy prey. Then it sucks the food into its mouth with blinding speed. Slow motion shows the accuracy of the attack. Once in the hunter's sights, the victim doesn't know what's hit it. All night long, it picks off the sluggish reef fish. The fanfare of spines protects it from counterattack. Another night stalker is taking advantage of the sleeping fish. It's a common cuttlefish, with uncommon intelligence. A camouflage virtuoso, it changes colour at will, and has excellent eyesight, able to pick out prey in almost total darkness. Closing in, it flushes white as it goes for the kill. The target seems oblivious to approaching danger. It's all over in a split second. Here's the kill at a fraction of its actual speed. First, the cuttlefish creeps as close as possible, bracing itself against the floor. Its two longest tentacles reach out, but don't strike until they're almost touching the prey. The darkness hides much larger predators, including a distant cousin of the cuttlefish, the Humboldt squid. At three metres and 100 kilos, these ghostly apparitions leave the ocean depths at night to feed in lighter waters near the surface. Their shifting colours mesmerise prey. The Humboldt strikes like a rocket from below, enfolding its prey in ten deadly tentacles covered in powerful suckers. Each sucker disc is lined with razor-sharp hooks surrounding the enormous beak. Once attached, the hooks shred flesh and skin, and the beak bites deep. These eerie creatures inspire fear in those who encounter them, and with good reason. Aggressive by nature, they'll attack almost anything. Sharks, humans, even each other. In the darkness, danger is hard to see. This is a sea wasp, also known as a box jellyfish, notorious for its lethal sting. The slightest contact with its trailing lines can kill a human being in minutes, never mind a small fish. Once it makes a catch, the booty is hauled inside the body to be digested. Other jellyfish are active by day. With the first light of dawn, huge swarms of moon jellyfish drift towards the surface. Ocean currents may bring them together in their thousands. They trawl the water with their stinging tentacles, but they in turn are hunted by another, larger jellyfish, the stinging cauliflower. The cauliflower has hundreds rather than dozens of tentacles, and easily overwhelms smaller relatives. Daylight filters down to the reef, and a little goby fish starts the day. But it's not alone. This is the proboscis of a kind of underwater snail, the cone shell, loaded with a poisonous harpoon. One touch would mean instant death for the goby. The gobies stand their ground, but one of them gets too close. The goby is paralysed and consumed whole. The baler snail can't hunt by sight, its vision is too bad. But it makes up for its tiny eyes by having a really big nose. It sniffs out smaller relatives, like this tun snail. The tiny trunk acts like a siphon, testing the water to pick up the slime trails of others. The tun snail leaves a telltale scent. The chase is on. The baler finally catches up, and wraps the tun snail in its mantle. Once inside, the tun snail is slowly dissolved by digestive juices. Another underwater snail, the helmet conch, also follows its nose. It tracks the scent of sea urchins. The urchin doesn't know it's coming. Yet. If it did, it could easily outrun the conch on its thousands of tiny tube feet. The helmet conch glides into position, and the urchin gets no warning until it's too late. The helmet lifts its heavy shell, and pins the urchin against the rock. Undeterred by its victim's spines, it slowly sucks out the urchin's soft innards. Bat stars, both red and white varieties, are also slow motion hunters. Even slower than the snails. Right now they're on the attack, but you wouldn't know it. Not without speeding up the action. Once again, a black sea urchin is taken by surprise. The smaller white urchin is quite nimble in comparison. Swarms of these tiny predators overpower and eat their larger cousins. At 50 times the normal speed, the violence of these skirmishes is revealed. This starfish is much bigger than the bat star, with a much bigger appetite. It's a sun star, nearly a meter across, that will devour anything it can trap beneath its 20 legs. Waves of brittle stars flee from its path. This one is safe for the moment. It's hitching a ride on the predator's back. But the sun star is heading for larger prey, a succulent scallop. As the carpet of brittle stars clears, the scallop is left exposed to the sun star's probing arms. The scallop isn't helpless. At the last moment it snaps shut and jets out of harm's way. Starfish may be slow, but they're effective predators. The leather star hunts sea anemones. It seems a fair fight. Both contenders are blind and usually very slow movers. But once alerted to the danger, the anemone springs into action. Venom is the first line of defence. It swipes at the leather star with stinging tentacles. If poison fails, the anemone has another tactic. It simply releases its grip on the reef and swims off to find a new home. And there's nothing the leather star can do about it. Once safely out of range, the anemone chooses a suitable spot. This time with a bodyguard. Life and death struggles are constantly taking place beneath the waves. But some encounters are more dramatic than others. Twice a year at full moon, hundreds of thousands of opalescent squid come together. They gather for the final act of their lives, a mass mating ritual. Each male catches hold of a female, turning red to warn off other suitors. Then he deposits sperm under a fold in the female's body. The female produces a long egg case packed with 200 eggs. And while the male may leave to seek another mate, she finds a sandy spot to plant her precious cargo. Intent on their mission, the squid lose all fear of death. Stingrays and other predators move in for the kill. The squid's fate is sealed anyway. The ocean floor is carpeted with eggs, but the exhausted parents are now dead or dying. All their strength has gone to produce the next generation. Sand dabs squabble over the corpses and soon other predators gather for the morbid feast. A sea anemone gets a giant helping, and so does a decorator crab. Nothing goes to waste. This is one meal the scorpionfish doesn't need to ambush. Soon the feeding frenzy is over and life for predators and prey returns to normal. Around the coral reef and out across the open ocean, the battle goes on. Every creature must be ready for the next deep encounter. you