20 Nightmarish Animals That Lurk In The Amazon River

A trip up the 4,000 miles and more of the Amazon River may be the stuff of dreams for any would-be explorer. But those dreams could quickly turn to nightmares thanks to the terrifying characteristics and behaviors of some of the native animals. Leeches with sharp teeth, sharks 2,500 miles upriver and fish that will invade your most private parts are just a few of the horrors that await you.

1. Tyrant king leech

Scientists only described this fearsome member of the leech family in 2010, naming it Tyrannobdella rex or the tyrant king leech. The animal can grow to a length of three inches and it has large sharp, teeth. It’s what it does with its teeth that is horrifying. This leech can use its teeth to hack away at the mouth of any mammal it catches on to. And it’s not just the mouth – it will chew into any orifice it finds, including the most intimate ones.

2. Amazonian giant centipede

This multi-legged beast can grow to a length of 12 inches. The Amazonian giant centipede is a feisty creature capable of taking on, killing and eating tarantulas, lizards, bats and birds. The centipede does have a poisonous bite, but this is not fatal to a healthy adult human. However, if you are up the Amazon with a small child, beware. A tragic case was documented in Venezuela when a centipede bite resulted in the death of a four-year-old child.

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3. Black caiman

Go for a swim in one of the slower-flowing sections of the Amazon, and you might come across one of these. Or, more likely, it will come across you. The black caiman is the Amazon’s biggest predator, and it will eat pretty much anything it can catch. It’s said that a mature adult specimen can grow to a length of 20 feet with a weight of 2,400 pounds. On a cheering note, if a black caiman takes you, it will drown you before snacking on you.

4. Bull shark

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Usually, a shark is not what you expect to encounter on a river. But the bull shark has been recorded as far as 2,500 miles upriver on the Amazon, penetrating as far inland as northern Bolivia and Peru. At mealtimes, the bull shark enjoys, among other things, birds, dolphins, turtles and other bull sharks. But the bull shark doesn’t turn up its nose at human prey. Some 69 unprovoked attacks by bull sharks on people have been recorded. Yikes!

5. Candiru

The candiru, also known as the vampire fish, is living proof that you don’t need to be huge to scare the living daylights out of people. Most species of candiru grow no more than seven inches in length. It’s hard to untangle fact from fiction here, but natives of the Amazonian basin are said to believe that the fish can swim up a man’s penis. If true, this is made doubly horrifying by the fact that the little fish has spikes on its gills with the points facing rearwards.

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6. Green anaconda

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The green anaconda is enormous, capable of growing to a length of more than 17 feet and weighing in at a far from petite 215 pounds. The green anaconda, which lives mainly in water, dines on anything from caimans to tapirs and jaguars. It kills its prey by wrapping itself around it and crushing the unfortunate victim to death. Female anacondas are said to quite enjoy eating the occasional male anaconda, but only smaller ones.

7. Goliath birdeater

Arachnophobes, look away now. This massive spider, a member of the tarantula family, is the world’s biggest in terms of body size, although one other, the giant huntsman, boasts a greater leg-span. The Goliath birdeater weighs in at not much less than half-a-pound and measures up to 11 inches across. But what are truly scary are its fangs – they can be a terrifying 1½ inches long. Despite its name, the spider’s diet is not restricted to birds. It will also happily chow down on snakes, frogs and rodents.

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8. Red-bellied piranha

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The red-bellied piranha is perhaps the most famous of the many perils faced by intrepid Amazonian explorers. After all what could be more frightening than to be eaten alive by a shoal of small fish? In fact, the fish can reach a length of up to 14 inches and fully grown specimens can weigh in excess of eight pounds, so they’re not tiny. The other secret about the piranha is that although it does display predatory behavior, it prefers to feed as a scavenger.

9. Poison dart frog

There are actually a variety of poison dart frog species in the Amazon, with each one apparently competing to see which is the most luridly colorful. In fact, as a rule of thumb, the more colorful the frog, the more venomous it is. The poison dart frog is generally small, less than an inch long, but some species can attain a length of 2½ inches. The frog excretes poison through its skin, so it will only kill you if you eat it.

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10. Payara

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If you come across one of these fish while you’re up the Amazon what you’ll immediately notice, and what will likely strike fear into your heart, is the two long fangs that the payara sports. Its alternate name, the vampire fish, is well-chosen. It uses these elongated, razor sharp teeth to stab and hold tight its prey. The payara is usually about a foot long, although unconfirmed reports have claimed a length of more than 3½ feet.

11. Electric eel

Being electrocuted by an eel is nobody’s idea of fun. But in fact the electric eel, although undoubtedly electric, is not an eel. Growing to a length of more than six feet, it’s actually a species of knifefish. Unfortunately, that insider knowledge will be of little comfort while the beast is electrocuting you. An electric eel’s complex physiology gives it the ability to administer high-voltage shocks. The electric current generated is not powerful enough to kill a human, but it is strong enough to give a distinctly uncomfortable shock.

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12. Arapaima gigas

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The Arapaima gigas is a massive Amazonian fish also known as a pirarucu, and this monster can grow to a length of more than 10 feet. The largest specimens can weigh as much as a hefty 400 pounds. In fact, this fish is not going to attack you. But bumping into one while you’re swimming in the Amazon is sure to give you a fearful shock. Sadly, this fish actually has more to fear from us due to overfishing.

13. Pacu

Now here is a fish that could give you serious nightmares. Not because it will try to eat you, poison you or electrocute you, but purely because of a remarkably strange facet of its appearance. Open its mouth and take a look inside. The pacu appears to have somehow got hold of a set of unmistakably human teeth. Although actually related to the piranha, the pacu, which can weigh well over 80 pounds, sticks mostly to a vegetarian diet.

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14. Giant otter

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We mostly think of otters as quite cute creatures. But the giant otter is a different kettle of fish and it can attain a length of up to six feet in adulthood. This otter is a formidable predator, capable of overpowering some surprising prey. Hunting in a pack, the giant otter is perfectly capable of overpowering and killing black caimans and anacondas although its favorite food is fish.

15. Mata mata turtle

This extraordinary-looking animal is found only in the basins of the Orinoco and the Amazon. The mata mata’s elongated snout looks almost like a miniaturized elephant’s trunk and the head is covered in weird protrusions. Growing to a length of up to 18 inches, this turtle eats only fish and invertebrates, so it’s no physical threat to humans. But its bizarre, otherworldly look might well cause nightmares if you stumble across one.

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16. Bullet ant

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Small compared to most of the animals we’ve described here, at just over one inch long, it’s nevertheless a fair size for an ant. But it’s not the size of the bullet ant that you need fear, it’s the sting. The bullet ant’s sting is reputed to be the worst of any of the bees, wasps or ants. Some of those who have experienced it compare the pain to that of being shot, hence the name. The ant has an alternate name, the 24-hour ant, since that is said to be the time that elapses before the intense pain of the sting subsides.

17. Brazilian wandering spider

Compared to a tarantula, the Brazilian wandering spider is fairly diminutive. But its nearly six-inch breadth is still easily big enough to scare even mild arachnophobes. Though truth be told, it’s not the spider’s size you need to be wary of. It’s the arachnid’s potently venomous bite, and the fact that it wanders about after dark. Strangely, one of the side effects of the bite in male humans can be priapism, unfortunately followed by impotence.

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18. Jaguar

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This is one apex predator that you’d prefer not to meet while hiking along the Amazon. In terms of size, it ranks at number three among the big cats, after lions and tigers. It’s also distinguished from many other cat species by the fact that it’s seemingly happy to take to the water. The jaguar is of course a carnivore, and not an especially fussy one at that, as it has no fewer than 87 prey species that it hunts and eats. It’s said the jaguar rarely attacks people. But rarely does not mean never.

19. South American bushmaster

With a length of up to 13 feet, the South American bushmaster holds the distinction of being the western hemisphere’s longest poisonous snake. And this member of the pit viper family is armed with a venom that is potentially deadly. This snake can bite repeatedly and is capable of injecting prodigious quantities of venom. Fortunately for us humans, the South American bushmaster tends to stay away from us. But if you see one, run.

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20. Amazon tree boa

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This snake can grow to as long as six feet and more, and what is important to know about it is that it has a reputation for being particularly belligerent and for attacking without prior warning. Thanks to its very sharp teeth, the Amazon tree boa can inflict a painful bite, although thankfully this serpent is not venomous. Frogs, birds, bats and lizards are all regarded by this snake as acceptable snacks.

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