Underwater Killers (Full Episode) | World's Deadliest

Ah, nothing like a fun day of frolicking at the beach. But venture past the surf and things could get ugly. For this is where nightmares lurk. Armed with jaws, poison, and unimaginable powers. They say, enter at your own risk. But this time, it just happens to be true. A scuba diver. Dead in the water. There's no sign of trauma. No equipment failure. Something down here could have killed him without leaving a mark. He was probably checking out the bizarre life forms in the Pacific Ocean. But sometimes, the bizarre can be deadly. This is an electric ray. It's called the torpedo and it's massive, weighing up to 80 pounds. Unlike other rays that swim with fins, the torpedo propels itself like a stealth bomber with a shark-like tail. And it's armed with an explosive weapon. It stuns and kills with a powerful electric shock. Modified gill muscles contract in waves. Victims are trapped under a dome of terror. Then caught in the crossfire of an electrical current that racks them with repeated shocks. For the most part, the ray uses its weapon to shock fish for easier swallowing. But when startled by, say, a diver, the torpedo can unleash up to 50 volts. Enough to electrocute and ruin what was supposed to be a dream vacation. You don't have to be big or electrified to be a killer. Some come disguised in small, pretty packages. The blue-ringed octopus is barely bigger than a golf ball, scouring the tidal pools of the Indo-Pacific for treats. It's completely deaf, but makes up for it with keen eyes and a killer sense of smell. A crunchy little crab is clueless. A quick dash, a quick bite, and then a quick death. The poison paralyzes the hapless crustacean. After all, it's powerful enough to kill a human in just 90 minutes. It contains tetrodotoxin, and it's a trendy choice among poisonous animals. Pufferfish and cone snails use it too. The poison is made by bacteria living in their saliva glands, and it packs a powerful punch against prey and, when necessary, predator. Normally, this eight-legged slinky is a dull yellow with dark rings. But spook it, and tiny ink sacs under its skin rise to the surface and turn the rings a brilliant neon blue. A vibrant warning to play with this fella at your own risk. This horde of spiny lobsters is on a frantic hunt, not for prey, for protection. These horny-eyed, shy scavengers are normally found hiding in cracks and crevices. But fall storms force them out into the open, where they're vulnerable. The leader follows the current to deeper, safer waters. The others use their antenna to play the following game. Eventually, they reach the refuge of their new home, where they can once again be predators. Predators that capitalize on the dead. There's no fight or flee left in this guy, so all kinds of critters belly up to the dinner table. For once, lobsters are safe in a shark's presence. They make quick work of the carcass, leaving only bits of bone and teeth behind as evidence it ever existed in the first place. This little blue fish doesn't look very deadly. Guess we're not talking about the little blue fish. Stonefish hold their meals up just like a vacuum cleaner. In one massive gulp. Sure, it may look slow. An easy target for a predator. Think again. Thirteen poison-tipped spines adorn its dorsal fin. And each contains a mix of paralyzing neurotoxins and tissue-destroying myotoxins. No wonder the stonefish is considered the most venomous fish in the world. It's a lethal threat to humans, too. Especially since it looks like an ordinary rock in the ocean. The stonefish. An extraordinary killer. This guy's so ugly, he's cute. The striated frogfish, aka hairy frogfish. A good hair day, it isn't. But hunting's what's on this frogfish's mind. He settles down to the perfect camouflage. Then goes to town. Whipping a worm-like lure around on top of his head. The frogfish is fishing. Anything brave enough to investigate isn't long for this world. With skills like that, who cares about bad hair? Some have skills. Others have equipment. Moray eels hide in rocks and reefs until nighttime, when they slink out to hunt. Jaw-popping helps them breathe and makes them look ferocious. Two nostrils draw in water over a highly developed olfactory gland, which detects the scent of prey floating by. Here's where the equipment comes in. The outer jaws seize the fish. Then a set of inner jaws go to work. Yes, moray eels have not one, but two sets of jaws. The second set acts as a claw machine and pulls the food into the eel's stomach. The pufferfish puffs up to double its size. Masterful move. The eel's determined to get his dinner. But it's an exercise in futility. The only way to win this battle is with a third set of jaws. Maybe things will go a little easier for this peacock flounder, who's eyeballing a nearby female. He thrusts his pectoral fin high in the air to get her attention. But that can also get the attention of predators. The more he tries, the more she rejects him. Typical. It's a disastrous date and about to get worse. A huge snapper is sniffing around. Luckily, he's curious, not hungry. Nothing like a near-death experience to get you in the mood. The two flutter around, releasing fertilized eggs into the water. Then quickly go back to their separate corners on the seafloor. Legend has it that sea monsters live here in the cold, dark waters of the Pacific. And guess what? They do. This beast is a giant humbled squid. And if you think it's a candidate for calamari, check this out. They can grow as large as a man. Without warning, they rise from the darkness to feed on fish at the surface. Sometimes they look like ghostly spirits. They turn white by opening and closing sacks of pigment in their skin. When alarmed or aggressive, they turn red. As in, beware. Their nickname, red devils. Few willingly tangle with humbled squid. But this filmmaker descends into the darkness to capture one-of-a-kind footage. At first, they're curious. Then they turn aggressive. In the attack of the killer squid, tentacles grab his mask and regulator, threatening his air supply. Beating them back, he makes for the surface. It's not a dream or a legend. It's real. A real-life nightmare. Exotic, majestic, and completely toxic. The lionfish has long flowing fins to hide an arsenal of poisonous spines. And a flashy pattern to send a clear message to predators. Look, but don't touch. People tend to ignore the warning, which explains the 40,000 cases of lionfish poisonings every year. Symptoms range from severe pain to convulsions and even heart complications. Armed with a gaping mouth and voracious appetite, they cockily prowl the reefs for fish and invertebrates. The prey is herded into position. Again, a doomed little blue fish. Confused, cornered, and consumed. Then they saunter off to search for their next course. Without a lot of predators to worry about, life's pretty good for these spiky sea creatures. Tube feet wriggle. Red stalks bristle. Those who touch it instantly regret it. This is the fire urchin. Like all sea urchins, the fire urchin is an echinoderm, a family of slow and spiny invertebrates. Other members include sea cucumbers and starfish. In fact, a sea urchin's body design is a lot like a balled-up starfish. Its plate-covered top has hundreds of spines dotted with poison-filled sacs that burst on contact. If that's not enough, they have another defensive weapon hidden in their spines. Jaws. They aren't real mouths, but they look like it. These grasping appendages clean, collect food, and defend with even more poison. This guy's only about eight inches wide, but he packs a hefty punch. So stay clear of the fiery red ball, or you might get burned. Let's face it, this shark looks like a freak. What's with the huge flat head and bulging eyes? Hammerheads may be on the odd side of attractive, but they're mysterious, fascinating, and deadly. A huge olfactory cavity allows them to smell in 3D and snatch prey without even seeing it. So they're master hunters, even in the dark. Special pores called the ampullae of Lorenzini detect electromagnetic fields given off by other animals. And hammerheads have more than any other shark or ray in the world. They can pick up electrical currents down to a hundred millionth of a volt, like the beating heart of a fish or a stingray gliding over sand. For a slick move called the pin and pivot, enter the spotted eagle ray, one of the hammerhead's favorite snacks. In an instant, one entire wing is gone and it's left in a pool of blood. The shark actually uses its big flat noggin to pin its prey to the ocean floor. Then it rotates and pivots to pick it up and chomp it up. So it may look funny, but the hammerhead is an evolutionary wonder, an agile, crafty, intelligent killer. Reefs attract some of the most beautiful fish in the world. Then there's this guy, the great barracuda. And what it lacks in looks, it makes up for with speed and wildness. One of its best talents is ambushing prey. When the barracuda finds a target, it slices through the water, then slices through its prey. And not with one row of teeth. Try two. An inner row of large dagger-like teeth clamps down and holds it in place. Then an outer row of smaller teeth cuts it to pieces. It's an effective design that works well on fish or people. The great barracuda is responsible for two deaths and blamed for many more. So unless you want to end up on its dinner plate, stay out of the way. It might come as a surprise to see a seal in a nightmare show, but it's no mistake. Especially when it comes to the leopard seal. They out hunt every other seal out there and even like to feed on their own kind. Reaching 12 feet long and 1,000 pounds, they're one of the Antarctic's top predators. And they back up their reputation with huge teeth that they sink into krill, fish, and penguins. Especially penguins. Leopard seals top out at 25 miles per hour. But penguins are more maneuverable. So the leopard seal has no other choice but to change his game. He flops onto the ice for a land ambush. Finally, it looks like dinner's on the table. Unless you're smart enough to play dead until your killer looks the other way. In a genius escape, this penguin scoots himself free. This one doesn't. It's big, slow, and certainly not the scariest of predators. But give it some credit. Loggerhead turtles have massive heads. A powerful set of jaws. And only have to surface every 30 minutes or so to breathe. A sharp beak transforms it into a prehistoric monster for a slipper lobster. The outmatched crustacean is armed with little to defend itself. So all it can do is try to out swim the turtle. A battle of the slowest begins with a chase. And ends with a chop. It's a ray that looks like a shark. That looks like a tool. And it's performing an underwater version of Texas Chainsaw Massacre. With that huge saw on the end of its face. It's called a rostrum. And all sawfish have one. Some can be as long as a person. But no matter the size, they all pretty much do the same thing. Defend against predators like sharks. And detect prey with electromagnetic sensing pores. Which comes in handy in murky water. But what we all want to know is can the sawfish actually use its saw like a saw? Scientists say yes. Sawfish slash and stun prey with quick powerful swipes. Then pass over it and swallow it whole. A delicious end to a real life horror flick. Some nightmares aren't just scary, they're sick. Notice the pearlfish perfectly camouflaged in the seagrass. Spook it and it relies on an extreme and disgusting survival tactic. Enter the sea cucumber. A spiky crawling feeding tube that actually provides a safe haven for the pearlfish. When threatened, the fish locates the cucumber's rear exit. And then inserts itself, tail first, up into the intestines. The pearlfish is safe. The sea cucumber was too humiliated to comment. They come in all shapes and sizes. Colorful, blind, brainless blobs. Most are pretty harmless. Not this one. The box jellyfish is a highly evolved killer. Its venom ranks among the most deadly in the world. They don't just drift, they move. Six eyes sit clustered on all four corners of their bell. 24 in total. Up to 15 tentacles grow up to 10 feet long. And each has about 5,000 stinging cells. Which were triggered by this doomed fish. Toxins paralyze the victim to avoid a struggle that could damage the box's delicate tentacles. Then, dinner is served. A frozen treat locked in an agonizing screen. Poison is also lethal to humans. Heart, nervous system, and skin cells. Victims can drown from shock or die of heart failure. Beaches in Australia are sometimes forced to close for the summer months due to box jellyfish blooms. Because the worst danger is the one you don't see coming. Or it's the one you see clear as day. Powering through the water up to 30 miles an hour, killer whales are hard to miss. And they didn't get that nickname for nothing. Four inch long teeth rip through their favorite prey with ease. They average over 20 feet long and weigh as much as six tons. But killer whales rely on a lot more than size and speed to be killers. Try teamwork and tactics. Sometimes in groups of 40. This time, the target is a seal and he's used for target practice. A teaching lesson again and again. When practice is over, so is the seal and can't stop their voracious appetites. The hungry orcas propel themselves onto the beach to snatch up sea lions. Despite the risk of being stranded. But not all sea lions meet a quick end. One unfortunate pup is brought to the juvenile whales alive for them to once again practice their hunting skills. The killer whale, a top predator. And now a mantis shrimp interlude whose eyes are the most complex of the animal kingdom. They can see infrared, ultraviolet, polarized light and focus with trinocular vision for enhanced depth perception. All the better to smash, spear and eat you with. Like there isn't enough venom in the ocean already. The banded sea krait is more deadly than most cobras. They're descended from the same ancestor. But these guys are specially designed for life in the water. Its right lung runs nearly the entire length of its three foot long body. So it can hold its breath for about 30 minutes. A paddle shaped tail propels it to the seafloor where it can scope out its favorite prey. Eels. Yes, a snake acting like a fish hunts a fish then acts like a snake. And he's caught a whiff of something tasty. It latches on to the eel's face to keep it from squirming while the poison does its work. Neurotoxins paralyze the eel and myotoxins destroy muscle tissue. Eventually the eel loses the fight and suffocates. Which frees up the banded sea krait to slither off for another meal. At first glance it seems that we're moving on to a lighter note. Everyone loves cute clownfish, right? Right. But maybe not so much for their big creepy friend right behind them. A sea anemone. Clownfish are immune to the sea anemone's paralyzing stingers. Thanks to a thick coat of mucus. So they're protected from any predatory fish. In return clownfish keep the sea anemone free of parasites. Which makes them in a way friends with benefits. Still feeling the love? Not all predators are fast or agile or sneaky. You don't have to be if you're patient. Like the cone snail. Although it doesn't look like it has much choice. At least it's armed with a rock hard shell to protect it as it scours the seafloor. Between its eye stalks is a long siphon that sniffs out prey. Like this camouflaged blenny fish. A long tube called the proboscis edges toward the fish. Inside is the snail's secret weapon. A poison tipped tooth that acts like a harpoon. The blenny is completely oblivious. Then completely paralyzed the cone snail gulps it down whole. So patience can be a virtue. Patience and poison. Maybe heading to a river is safer. Normally catfish get served up on our tables. But it looks like those are turning. Meet the wells catfish. A monster that can reach nine feet long and weigh in at 200 pounds. A more fishing pole won't get the job done. Legends tell of humongous specimens dragging fishermen to their doom. Okay, so maybe you won't get eaten alive by what you made for dinner. But the fish are being imported to rivers like this one in Spain. And they grow like gangbusters. Long whiskers covered with chemical receptors feel and taste things on the riverbed. So they're expert hunters. They devour the living. And scavenge the dead. Bad for the local fish. Good for the wells catfish. Maybe the focus should shift back to the legends. They're masters of disguise. With eight arms. Hundreds of suckers. Three hearts. Wicked smart. And an ink sac. What more could a cephalopod want? Octopuses are boneless creatures. Soft and squishy. So they can stuff themselves into the smallest of cracks and holes. Then their hunting skills kick in. A crab doesn't stand a chance. To see how pliable they really are, we put an octopus to the test. It stretches and squeezes through tunnels as small as a quarter. In its natural habitat, this ability helps it ambush prey and hide from predators. It sniffs out hidden food in the tanks. And even figures out a way through the maze to find dinner. Forget about locks. This guy easily opens the tank's sealed covers. And escapes. Now that's what we call a double-O octopus. Ooh, a jawfish. Sounds spooky, right? Well, consider this. He's not tossing his cookies. He's tossing his family. This mouth-brooding expectant father is aerating the eggs to help them develop. He'll keep them in his mouth until they're big enough to swim on their own. But let's face it. One swallow and he's a mass murderer. Speaking of murderers. Piranhas have gotten a bad rap for decades. But they earned it. Really. Shark-like feeding frenzies. Teeth that puncture, shear, and strip victims down to nothing but bare bones. In gangs of up to a hundred, they search for easy pickings in the Amazon River. Like this unfortunate baby egret. Who rings the dinner bell the second he hits the water. Monster jaws come running. It's over in minutes. But piranhas are more than just frenzied predators. They scavenge carcasses and even eat plants. So they school in large numbers for hunting and protection. At least there aren't any records of a person being eaten alive by piranhas. Not yet anyway. Not all underwater critters live life at a frantic pace. Some like to lie around like slugs. Literally. Sea slugs or nudibranchs are tiny, slimy, and pretty. Pretty poisonous. Some produce poisons. Others absorb poisons from their prey. This sea swallow even chows down on the toxic stingers of the Portuguese Man of War. The nudibranch absorbs them into its body to use for its own defense. So don't be fooled by pretty. Sometimes it can be pretty deadly. They're gigantic with massive heads and teeth the size of a human hand. They have the biggest brain of any creature on earth. And even provided inspiration for Melville's classic novel, Moby Dick. Sperm whales spend the majority of their time looking for food. But considering they need more than a ton of it a day, it's no wonder. Fish and squid are their favorite snacks. So with a kick of their powerful fluke, they sink a mile below the surface where they'll hang out for up to 90 minutes. There's almost no light, so they send out powerful ultrasonic clicks. The returning echoes reveal both the size and location of prey. Like the giant squid. We've seen what they can do to a diver's face. But a real-life battle between a sperm whale and a giant squid has never been captured on film. Sucker marks on their skin and squid beaks in their stomachs are evidence that the war is being waged and probably being repeatedly lost by the squid. There's no way to know for sure, but our money's on the sperm whale. Black groupers have some game of their own. They pretty much suck down anything that gets too close. Except for these gobies who, luckily for them, provide a special service. This patch of coral is a full-service cleaner station. A tiger grouper pulls in and the gobies go to work, picking off parasites and dead skin. The fish is cleaned and buffed to a lethal shine. The goby spared from being gulped down by the grouper. At least for now. It's one of the deadliest predators in the water. Freshwater, that is. And it may look like the whale's catfish's cousin, but this guy's far more dangerous. The electric eel. It prowls the murky ponds and river basins of South America. And just one shock can knock a horse clear off its feet. Each eight-foot-long eel can generate six or seven hundred volts. That's more than five times a standard U.S. electrical outlet. If a human's on the receiving end, sharp, stabbing pain, uncontrollable muscle spasms, and even cardiac arrest can occur from just a few jolts. So what's the secret to producing this much electricity? The eel's organs are jammed into the top fifth of its body. The rest contains roughly 6,000 specialized cells called electrocytes. Charged ions flow into each of these cells and create a current that can kill prey without even touching it. The electric eel has no teeth. It's not particularly fast. Its gills can't extract enough oxygen from the water, so it has to surface every 10 minutes or so to gulp down air. And if that wasn't enough, it's pretty much blind. But the small electrical pulses it generates helps the eel navigate rivers, detect prey, and predators. This juvenile caiman thinks he's about to get an easy meal. All he gets is electrocuted. But that doesn't stop him. He goes for another, then makes a smart escape. The eel remains master of its domain. They're poisonous, double-jawed, clever, and downright deadly. All of the world's waters are filled with critters that can kill. So beware. The next time you go in the water, you may have an underwater nightmare of your own.