in the rainforests of the Amazon basin, many animals have evolved to produce natural toxins, which they employ to deter predators or use to immobilize or even kill their prey. And as well as its many truly poisonous creatures, the Amazon is also home to animals that mimic the same characteristics, through colors and markings similar to those of venomous species, although they themselves are not poisonous.
More than one hundred poisonous dart frog species live in the Amazon basin. These frogs are mostly very small, no more than around 6 centimeters (2.5 inches) long, but a single frog can produce enough venom in its skin to be lethal to major predators, as well as humans. These frogs’ bright colors and dramatic markings are intended to warn potential predators. Traditionally, indigenous groups have used the venom from dart frogs to coat their projectiles with poison, which is how this group of amphibians got their name.
Also found in the Amazon basin are poisonous species of butterfly. One such species, Heliconius erato, better known as the “red postman”, possesses bright red wing markings intended to warn potential predators of its toxicity. By ingesting the leaf matter of poisonous flora while they are still caterpillars, these butterflies make themselves highly distasteful to predatory birds.
Of course, the Amazon’s most well-known venomous animals are its snakes. South America’s Amazon basin is home to at least seventeen species of highly venomous snakes, including seven species of pit viper and ten species of coral snake. The Amazon’s pit vipers include the notorious bushmaster (Lachesis muta), which at more than 2.5 meters (8 feet) in length is the biggest venomous snake in the Americas. However, while this snake has gained a fearsome reputation, very few of the snakebites inflicted on humans have ever been attributed to this species, which mostly limits its predatory activities to small rodents. Species of pit vipers are known to employ thermo-receptors located in the facial pits that give them their name, producing infrared thermal images with which they identify their prey. Some pit vipers’ thermal imaging system is so sensitive they can detect the temperature variation caused by a small rodent 15 centimeters (6 inches) away.
Some species of Amazon spiders also use venom to either kill or immobilize their prey. However, very few spiders actually constitute a threat to humans. Tarantulas inspire fear among humans because of their hairy bodies and large size. But, while their bite can be painful, the venom they produce is actually weaker than that which comes from a normal bee sting.
The Brazilian wandering spider is more of a threat than the tarantula. This commonly used generic term covers a family of eight different species, found in the rainforests of the Americas all the way from Costa Rica to Argentina, including Peru. Their venom certainly has the potential to harm or perhaps even kill a human, where no venom antiserum is available for treatment of the victim, but while Brazilian wandering spiders have been included in the Guinness Book of World Records as the “world’s most venomous spiders”, very few substantiated reports have been received of them biting humans.
At our own Tambopata Ecolodge, where we have worked for the past 30 years to protect the forests where we live and develop a conservation-based ecotourism model, we invite travelers to spend time with us and explore the Amazon basin safely, in the company of our experienced, expert naturalist guides.