Dangerous Animals You Wouldn't Want To See In The Amazon Rainforest

The largest rainforest in the world is a place that generates superlatives. It spreads millions of square miles across South America, bleeding into eight countries, and is more than half the size of the Lower 48 — yes, you read that right! Billions of climate-change-combatting trees and hundreds of indigenous tribes live in the rainforest, and in addition to the sizable population of humans that call it home, the Amazon is where you can encounter a treasure trove of plants and animals. 

Some estimates suggest that 10% of all species on the planet are found here, with new ones regularly discovered every year. Much of what visitors encounter is harmless — from tiny insects to the larger capybara, which looks like an oversized, sand-colored guinea pig. With its stocky torso and squat legs, it is undeniably cute. Yet, there are other creatures in the forest that travelers should make an effort to avoid, animals that may look sweet and innocuous but could leave visitors writhing in agony.

More than 100 species of the Scolopendra giant centipede exist around the globe, from the forests of Australia and Asia to spots in the Caribbean and South America. What they all share is that they are frightening to look at and are ruthless killing machines. The largest lives in the Amazon, the Scolopendra gigantea, often called the Amazonian giant centipede. With a seemingly impenetrable outer shell, length of up to a foot, and a wiggling method of movement that makes them hard to track — not to mention the huge number of little feet that shuffle it along — it just looks scary. 

It uses those feet to shoot toxic venom into the nerve centers of its prey, small animals that include bats, snakes, and even birds. The giant centipedes are just as comfortable in the water as they are hanging off the roof of a bat cave, and while they rarely kill people, their bites definitely will hurt, causing swelling and sharp pain. Look out for them in areas of damp undergrowth, among leaves on the ground, or in rotting wood. Better yet, don't look for them at all.

In the United States, crocodiles and alligators are to be dodged at all costs, and in the Amazon, the same is true for the black caiman. A huge animal with a buffet-ready appetite, these amphibious creatures can eat deer and cows with consummate ease. Much like their reptilian kin, caimans like to lounge in the sun to warm themselves and can stay motionless for what seems like an eternity. But when it comes time to feed, these creatures, which can weigh a tonne and grow to more than 15 feet, have no competitor. 

They are the top predator in the Amazon, and even jaguars are rarely a match for them. Caimans are extremely territorial, especially if there are eggs in their nest, and will take any advance toward them as a threat. They tend to be most active at night, when they hunt, and can quickly make a meal out of horses, otters, snakes, armadillos, and even humans if they so feel inclined.

The name of this ant doesn't refer to its compact, ruthless power but rather the sensation that a sting produces. Though the ant is only about an inch in length, its fierce bite feels like a shot to the skin, and a handful of these insects can easily overpower a human with that kind of pain. It's not the ferocity or size of the injection that is the most harmful aspect of a bullet ant attack, but the composition of the sting itself. 

The stinger, a tiny sliver that is around 2 millimeters in length, is filled with a neurotoxin that makes the prick intensely painful, really like a bullet, with that burning, searing torment lasting for many hours. It sounds like the worst possible torture, and it is, but for the indigenous Sateré-Mawé, it's part of growing up. For boys to graduate into full warriors, they must endure repeated stinging by these ants on their hands over a protracted period of time.

A viper found is many parts of Ecuador's Amazon, this reptile with a triangular head and brown skin is deadly. It lives in forests and fields, sometimes boldly venturing into homes, and prefers to be near water sources. They are idle by day, clumped under trees or shrubs, and start to move around sunset, picking their spots for ambushing prey. Sharp fangs are used to cut into their targets, injecting them with venom, and the snake will then wait for the prey to give up, or if they try to flee, follow their scent to the weakening prey. 

Rodents, lizards, and even fish are all part of the diet, but these snakes will also regularly down animals much larger than them. Humans won't automatically die from a bite but can expect to experience intense pain, lots of bleeding, swelling, infections, loss of consciousness, and tissue damage. Death is a slim possibility, but a possibility nonetheless.

The largest spider you are ever likely to see, the Goliath birdeater is a sly, shrewd hunter found in the forests of South America. They can live up to 20 years, with a leg span of a foot, and they have a diet that can be described as "eat anything." A type of tarantula, the Goliath birdeater's name is misleading since birds aren't its main dietary intake. They certainly are capable of eating one, but they are more known for their food sources of frogs and rodents. 

It uses fangs to inject venom into its prey, knocking them out before slowly killing them, pulling the animal back to its lair, and eating them from the inside out. The spider also has a crack defense system, with small, sharp hairs that can launch onto predators to deter them. Their bites aren't disastrous for humans, but they are definitely irritating, like the sting of a bee or wasp.

A type of pit viper, notable for its two tones — a leafy green top and sunny yellow bottom — this snake isn't large, but it sure packs a punch. The green jararaca is found at lower elevations and typically masses in forests near water, rarely staying more than a few feet above the ground. They grow to about 2 feet in length, sometimes a bit longer, and their relatively small size makes them nimble and efficient navigators around the Amazon. 

By day, they rest among the foliage, often in the shade around palm trees, their tales slung around branches or trunks. At night, when temperatures fall, they can use thermal sensors to detect the heat of prey. Food includes small birds, mice, frogs, and rabbits, while its toxic bite can lead to severe bleeding (the venom has anti-coagulating properties), headaches, irreversible tissue damage, loss of consciousness, and sometimes death in humans.

The biggest cat in the forest and the Americas, the jaguar is an intense hunter. One of the most powerful creatures in the Amazon, it's also one of the most elusive. Wary of strangers, jaguars are threatened by poaching and diminishing terrain caused by deforestation and agricultural development of the rainforest. The population of these speckled creatures has plummeted by 50% in the last century, and visitors will be extremely lucky to spot one on a trip to the rainforest. But, if you do see one, keep your distance. 

They hunt on the spur of the moment, eating what they find rather than planning and staking their prey — typical food includes deer, capybara, birds, monkeys, and fish (they are seasoned swimmers) — and are awake at night and by day. It's a jaguar's bite that is deadly, exerting enough pressure that it can puncture the tough skin of a caiman or a turtle's shell. For larger creatures, a bite at the back of the skull is the killer blow.

All piranhas are not the same, and of the 20 or so species that live in the Amazon, many pose no danger to humans. Visitors can happily swim in lakes where these fish roam without fear of a toenail being nibbled off. You might even have piranhas swim by and brush against you without noticing. But one piranha in particular isn't quite as pacifist-leaning, and that is the red-bellied piranha. Named for their fiery-hued undercoat, they can grow to more than a foot in length and weigh up to 7 pounds. 

They gnaw away at crabs, fish, and lizards, though not exclusively so, and can attack a young caiman, attacking in large groups to nip, bite, and chew an animal to death, literally. Their teeth are extremely sharp, and indigenous tribes have been known to use them as cutting tools and as weapons. if you dip your finger into the water at the wrong time, that digit can be gone in an instant.

A type of pit viper scattered across the continent that gives it its name, this rattlesnake can thrive in grasslands, dry habitats, and forests and often lives alone, not part of a larger gathering. Dusk and mornings are when these snakes tend to move around, and their bite can be extremely dangerous, though generally, they aren't bothered by humans, opting to usually ignore them or raise their heads in the face of an obvious or immediate threat. 

The South American rattlesnake eats mostly rodents, the easiest and most common food source in its environments. If it does bite a human, the victim can expect a host of symptoms, none of which sound like much fun. These include hearing issues, loss of muscle function (including the neck), partial loss of vision or even total blindness, failure of the kidneys, and breathing problems that can be fatal. Avoid the South American rattlesnake at all costs, although that should go without saying.