Ranking America's Deadliest Snakes (Full Episode) | World's Deadliest Snakes | Nat Geo Animals

NARRATOR: To most of us, snakes shout danger. And that's a valuable instinct. Every year, they bite over 5 million people. ♪ ♪ Many have lethal venom; others, primal aggression. A handful have both. Which snake is the most dangerous? It's the one right in front of you. What are your chances? We'll tally them up and tell you. North, Central, and South America. Home to over a billion people and millions of snakes. From venomous vipers to bone-crushing constrictors, which one should you worry about most? The Amazon. Synonymous with a snake so powerful, it doesn't even need venom to be deadly. The green anaconda holds the title; largest and heaviest snake on Earth. Nearly 30 feet in length, it's as long as a 10-wheeler truck. At a hefty 1,000 pounds, as heavy as a bison. Immortalized by film and labeled a vicious man-eater. It's a B-grade horror staple-- multiple rows of 100 backward-curving teeth. But what can it do to you? And just how deadly is it? On land, most snakes are quick and agile, but not this one. Anacondas thrive in a different domain. Water. It floats their bulk. In the water, heavy muscle transforms into supple, athletic movement. She can sneak up on you along jungle streams. She blends into the mottled riverbed. A small nostril and high-set eye is all you'll see of her. She can stay under for up to ten minutes at a time. You won't see her coming. A 1,000-pound snake, right at your feet. Her best tactic is the element of surprise, and this is what makes her dangerous to humans. Around 30 million people share territory with anacondas along the Amazon's rivers. Ample opportunity for unsuspecting humans to stumble on her. But although we may be easy prey, she sticks to a more predictable snake diet. Rodents. In the supersized Amazon, the world's largest snake hunts the world's largest rodent. Capybaras hang out in large family groups; safety in numbers. (squeaking) With webbed feet and a five-minute breath hold, they're also well-adapted to swamp life. The anaconda needs stealth and speed to take one down. (squealing) 100-plus teeth lock on like grappling hooks. 15,000 muscles crush with the strength of 18 men. Tighter and tighter, the extreme pressure overwhelms the capybara's circulatory system and stops its heart. Then, she pivots her jaw and stretches it. Super-elastic ligaments allow her to swallow massive prey. This capybara is the weight of a full-grown man. It's not surprising the green anaconda is the most feared snake in the Amazon. So, how does she score? Aggression in truckloads. No venom, but a vicious bite and deadly muscle power. Your chances of walking away are high, but still, a handful of people fall prey to the mighty anaconda each year. She takes her place at the top out of the gate. The anaconda lurks beneath, but the red-tailed boa watches from above you. She's a twentieth of the weight of her Amazonian cousin, but that's still a 50-pound snake. These bruisers can't bend and slither. Instead, they use their flexible belly skin to scoot forward without bending their spine, like giant caterpillars. She's as thick as your thigh, and she's getting too big for her skin. (birds squawking) During a growth spurt, snakes secrete a lubricant between their top layer of scales and the layer beneath. Which allows them to slip off their old skin and emerge shiny, supple and bigger. When they're young and small, many boas are sold as pets. But the snakeling will grow at least 10 times in size by the time it reaches adulthood. A 10-foot predator in your child's bedroom is definitely not a good fit. More than 20 cases of children being strangled or killed by their pet boas are on record in the USA alone. It's innocent, remains one of the world's deadliest snakes. Considering this childhood pet can live as long as 40 years in captivity, boas are best left in the wild, hunting for their own natural prey. NARRATOR: In the deeper shadows of the Amazon Basin, danger awaits. (howling) This big hitter brings venom to the table. The South American bushmaster. He's the longest venomous snake in the entire Amazon. Averaging over 6 feet in length and sometimes reaching nearly double that. He's also a top contender for the longest fangs of any snake. Add potent venom, and he's up there with the deadliest snakes on the continent. But what are your chances if you're faced with one? Unlike the constrictors, he uses venom to immobilize his prey, backed by a highly sensory strategy to track down his dinner. He uses his tongue to follow scent trails. A snake's tongue is 10,000 times more sensitive than the human nose. He's collecting scent particles from the air. Then he "tastes." A special organ on the roof of his mouth processes the scents into information. He can even taste in 3D; picking up different scents from left and right, on each fork of his tongue. Rodents reuse paths fairly regularly, so the resourceful bushmaster just needs to follow the "rodent runway." If he waits long enough, his dinner may come to him. (birds chirping) If you tread on him now, you're in trouble. They're called pit vipers because of those holes below the eyes. Each contains heat-sensitive organs that detect minute temperature changes. The rat approaches. The bushmaster's already mapping its body heat. (hiss) 1 1/2-inch fangs, like hypodermic needles, deliver a massive dose of venom, which destroys tissue and causes internal bleeding. Fangs so long, venom goes deep into muscle. You'd stand a 20% chance of surviving this bite. The rat? Zero. Using only the fangs, he guides his meal down his gullet. Despite his size, the bushmaster gets by on 10 large meals a year. This rat could last him a month. The bushmaster brings venom and supersized weaponry right to our feet, but his habitat is remote, dense forest. So, he doesn't come into contact with people often. When he does, he tries to warn you. He shakes his tail in defense, But there's no tell-tale rattle. (slapping) It's earned him his Latin name: "silent fate." Bushmaster venom is unforgiving, and the antidote is unreliable. He keeps his aggression in check by steering clear of humans. But when he does bite, people lose limbs and lives. The bushmaster's venom puts him in pole position. In the open undergrowth of Costa Rica, a killer with manners. NARRATOR: Rattlesnakes are more upfront than bushmasters. They use their noisy tails to warn, "Back off. I can kill you." (rattling) Locals call this one cascabel, after a dried chili pepper with rattling seeds and a searing burn. When rattlers shed their skin, a small section stays behind on the base of their tail and hardens into a new segment of the rattle. One segment knocks against another, and that's what you hear when you walk too close. Rattlers have a habit of sitting tight, not fleeing. And when they strike, they're lightning fast. From 0 to 100 miles an hour in just a tenth of a second. That's 50 times faster than a Formula 1 car out of the starting blocks. (man groans) Their venom is monstrously toxic. It attacks both the circulatory and the nervous systems. A two-pronged approach. First, searing pain as hemotoxins swell, bruise and blister the bite site. Then, wrenching muscle spasms and respiratory distress as neurotoxins damage and paralyze nerves. Finally, a strong chance of death from respiratory failure. Cascabel venom can rupture your organs and stop your heart. They're aggressive and quick to strike. Responsible for thousands of human snakebites per year and a high fatality rate. It's more than enough to outgun the non-venomous constrictors and bump the bushmaster into second place. Central America-- a diverse snake habitat, also highly populated by humans. A recipe for disaster? Most definitely. There's a niche for each of the hundreds of snake species; every one of them specialized killers. Central America is an evolutionary snake pit. Snakes across the globe live right under our noses. And many are much closer than you think. (vendor shouting) Some take camo to new heights, making them almost invisible to the human eye. The eyelash viper is so cryptic that she often winds up in our midst, right across Central America. Ending up at this busy market wasn't the plan, but she's trying her best to blend in. Because of her weaponry, she's a deadly neighbor. A bite from this beauty is serious. It's not her fault, but her venom is potent and sometimes fatal. Why so dangerous? It's a side-effect of being a perfectly evolved forest hunter. Lash-like modified scales protect her eyes from prickles and thorns in dense rainforest. A neat accessory when you don't have eyelids. A further attribute is her incredible prehensile tail, which holds her just at face height. Like a deadly bungee cord. Waiting, not for you, but her prey. NARRATOR: Inside her mouth, a specialized tube allows the eyelash viper to breathe if her throat is crammed with large prey, and an impressive set of fangs fold back parallel to her jaw, ready to be unleashed. (frogs chirping) All this deployed at human head height. Like the cascabel, the eyelash viper has both hemotoxic and neurotoxic venom, inflicting massive hemorrhaging and a swift death on her victims. She's not aggressive but comes into contact with people often, pushing her defensive bites into the double figures. At worst, causing one fatality per year. Still good enough for a worthy third place on the leaderboard. Over 300 million people. Over 20 species of venomous snakes. North America is snakebite central. Between 7,000 and 8,000 people are bitten every year. You're in big trouble if that bite is from one of these two. Hugely different in looks and M.O., but both armed with deadly venom. The coral snake has the opposite of camouflage. It uses color as a siren. "Stay away. Don't touch." Most snakes sit tight or flee, but corals are movers and shakers. Their tiny fangs leave a mere pinprick and only deliver 1/1000th of a teaspoon of powerful, neurotoxic venom, but that's all that's required to kill us and their prey-- other snakes. Their bright, shiny scales just beg to be touched, but that's not their game. (children talking) They're shy and often use deception as defense. Being conspicuous, they resort to hiding their bodies. Leaving a loop of tail aboveground as a decoy to draw attention away from their heads. (children laughing) If a predator reaches for the bright loop, the coral strikes. GIRL: Ow! BOY: Maggie! NARRATOR: It's no more than a pinprick, and symptoms can take a whole day to appear. By then, it's too late. Neurotoxins disable the nervous system, disrupting the connections between the brain and muscles... (crash) (siren) ...leading to respiratory or cardiac arrest. In North America, this toy-like snake is responsible for up to two dozen bites per year, most of which are extremely serious. They are so feared that some snakes take advantage of their reputation. Mimicking his stripes, the harmless false coral snake fools predators into thinking he's his highly dangerous cousin. True coral snakes are the tricksters in the pack. They're small but potent. Deadly but shy. Which keeps them in line behind the vicious vipers and the colossal constrictors. America's cliché-- cowboy country. (horse neighs) (bird shrieks) And home to the most notorious vipers on Earth: rattlesnakes. The western diamondback. Icon of the Wild West. His signature rattle strikes fear into both man and beast. Ironically, he can't hear it himself. Snakes have no eardrums. Instead, his bulky bottom jaw acts as an antenna, tuning in to the smallest vibrations in and on the ground. (cattle lowing) He feels the cowboys passing. (hoofbeats) His instinct is to stand his ground. He'd rather avoid confrontation than strike unnecessarily. (moo) He's known to kill livestock, but that's not his intention. Ranches are ideal breeding grounds for his favorite prey: rodents. NARRATOR: Is the western diamondback a pest or pest controller? (wings flapping) Opinions may differ, but like all snakes, the rattler needs to kill to survive, and there's a juicy meal in this barn. His tongue is his GPS, tracking scent cues in his surroundings. Like the bushmaster, he's not actively stalking but smelling his way to the best ambush site. In the gloom, his thermal pits paint a picture in body heat. So, he can "see" the rat, even in pitch darkness. Now, he just needs patience. (squeak) Tag and release. One strike is all he needs. The rattler's huge venom glands hold enough hemotoxins to kill 300 mice. But he controls how much he delivers. It's not long before his prey succumbs to the potent, fast-acting venom. Without limbs or teeth to tear food into bite-size chunks, snakes swallow their prey whole. Venom is incredibly helpful. It starts to digest the meal, even before the snake has swallowed it. Their toxic drool has become their finest defense. So effective, that both man and beast yield to snakes. In cowboy country, that's important. Where western diamondbacks and human territories overlap, thousands of people are bitten each year. So, how do they tally up against their rivals? Huge venom yield. Defensive attitude. Frequent bites, with a high mortality rate. They outgun the previous contenders on every count. It's a sharp shoot to the top of the leaderboard. When judging a snake's deadliness, size, fangs and venom are big factors. The eastern diamondback rattlesnake has all three. He's the largest and heaviest rattler, armed with the longest fangs and deadly venom. When a fang starts to wear out, another replaces it. Long fangs deliver venom deep into the internal organs, quickly destroying tissue and rupturing blood vessels. If this snake bites you, you'll be lucky just to lose a limb. It's good news that the eastern diamondback sticks to dense, remote habitat, well away from humans. He's master of the undergrowth. Instead of us, he shares habitat with another deadly snake: the cottonmouth, or water moccasin, the only semi-aquatic pit viper in the world. He makes his living on a diet of fish, frogs and other amphibians, but he's also an opportunist. And this is a snake-eat-snake jungle. Cottonmouths are cannibals. Head-to-head, the snake that strikes first, lives. This cottonmouth is much bigger. He has the eastern diamondback for breakfast. The rattler's immune to the venom of his own species, but not to others. Antibodies in the cottonmouth's blood protect him from his toxic prey, breaking down the deadly diamondback venom as he ingests it. To fellow snakes, the cottonmouth is a deadly rival, but he lacks the potency and aggression of the rattlers. He bites a few hundred people per year, but with the right antivenom, survival rates are good. has more potent venom, which translates to a 30% mortality rate if you're bitten. He ups the stakes to top his competitor and become the deadliest snake on the chart...for now. We've seen snakes that rattle and snakes that roll, some that deceive and others that cannibalize. But who's the deadliest of them all? NARRATOR: Like humans, snakes have colonized most of the habitable parts of our planet, but where our lives intersect, it often ends badly. Put a venomous, stealthy, defensive super predator amidst humanity... the stakes don't get higher. In the Americas, one snake comes into contact with humans more than any other. The fer de lance. (chirping) He's got the full package: camouflage, massive fangs, lethal venom, thermal pits and a notoriously vicious disposition. Strike first, ask questions later. (hissing) He's not afraid of anyone. In Central and South America, this feisty little snake bites tens of thousands of people every year, and hundreds of those strikes are fatal. Why? His lance-shaped head is a dead giveaway, but he's fast and hard to see. His camouflage is so effective that you don't see him before it's too late. He's not an intentional villain; the fer de lance is also drawn to settlements where rodents are rife. Both hemo- and cytotoxic venom kills quickly and destroys blood cells and tissue, ravaging internal organs and causing the victim to hemorrhage fast. With people at large and sunny porches to bask on, that's a disaster waiting to happen. (macaw squawking) This young lancehead has enough venom to kill four men. (squawking) Far from medical facilities and antivenom, an amigo caught napping could be dead in a matter of hours. Wrong place, wrong time. The fer de lance is not the biggest or the strongest or even the most venomous, but tally up its notoriously aggressive attitude, its proximity to humans, and its high strike rate, the results are clear. The fer de lance kills more people in South America than any other snake. It's enough to pip the rattlers to the post and top the chart as the Deadliest Snake of the Americas. Ever since Eve took the apple, snakes have had a bad rap... ...but in reality, they don't actively set out to harm humans. A life without limbs has armed them with an arsenal of skills to master their environments: chemical weaponry, highly evolved senses and incredible muscle power. Without snakes, rodents would run riot, agriculture would be plagued, homes would be infested. We may fear them, but give them space. Snakes make the world a far less dangerous place.