Continuing with the theme of gigantic reptiles, the largest snake in the world makes its home in the Amazon: the anaconda. While reticulated pythons are actually longer, green anaconda are far heavier; the females, generally larger than males, can reach 550 lbs, grow to over 29 feet long and reach 12 in in diameter. They are not venomous but instead use their immense muscular power to constrict and suffocate their prey, which includes capybara, deer, caiman, and even jaguars. Preferring shallower waters that allow them to stealthily sneak up on their prey, they tend to live in offshoots of the Amazon rather than the river itself.
Arapaima, also known as “pirarucu” or “paiche,” are gigantic carnivorous fish that live in the Amazon and surrounding lakes. Encased in armored scales, they think nothing of living in piranha-infested waters—and they are pretty effective predators themselves, feeding on fish and the occasional bird. Arapaima tend to stay close to the surface, because they need to breathe surface air in addition to taking in oxygen through their gills, and make a distinctive coughing sound when they emerge for air. They can reach 9 feet in length and weigh up to 200 lbs. These fish are so vicious that even their tongue has teeth.
While technically ocean-dwelling saltwater animals, bull sharks are quite at home in fresh water, too—they have been found as far down the Amazon as Iquitos in Peru, almost 2,500 miles from the sea. They have special kidneys that can sense the change in salinity of the surrounding water and adapt accordingly. And you do not want to meet one of these in the river; it is common for them to reach 11 ft in length and there have been reports of sharks weighing 690 lbs. Like many sharks, they have several rows of sharp, triangular teeth and immensely powerful jaws, with a bite force of 1,300 lbs. They’re also quite partial to a bit of human, being one of the most frequent attackers of people.
Electric eels are actually more closely related to catfish than eels, but you probably wouldn’t want to get close enough to one to find out. They can grow up to 8 feet long and can produce jolts of electricity from specialized cells called electrocytes arranged down their flanks. These charges can reach up to 600 volts , five times the charge of an average American plug socket, and enough to knock a horse off its feet. While one shock isn’t enough to kill a healthy adult human, multiple shocks can cause heart or respiratory failure, and it’s common for people to be stunned and drown after an eel attack. Many of the disappearances recorded in the region have been attributed to eels that have stunned their victims and left them to drown in the river.
The quintessential terror of the Amazon River, so widely feared that they have inspired a number of questionable Hollywood movies, red-bellied piranhas are actually primarily scavengers. That’s not to say they won’t attack healthy creatures; after all, given that they can grow to be over 12 in long and swim around in large groups, they tend to be more than a match for most animals. Like all piranhas, red-bellies have incredibly sharp teeth, one row on each of their powerful upper and lower jaws. These teeth are interlocking, which makes them perfect for tearing and rending the flesh of their prey. Their fearsome reputation mainly comes from sights of their “feeding frenzies,” where groups of piranhas will congregate on their unlucky prey and strip it to the bone within minutes.