Electric eels are elongated, fresh water fish, native to the Amazon and Orinoco rivers in South America. They are not really eels, but a kind of knifefish (and related to catfish). They are among the deadliest denizens of the South American rivers. It has not one, but three specialized organs to produce electric currents strong enough (600 volts, sometimes more) to stun or kill an adult human. It is believed that many “unexplained” disappearances of people while swimming in the Amazon and Orinoco rivers, could be due to them being stunned by an electric eel and drowning, or even, dying because of the eel’s discharge itself. Many of these deaths are often blamed on attacks by predatory animals such as piranha or caiman.
The electric eel doesn’t eat human beings; it feeds on smaller fish, crabs and small mammals. It only attacks in self defense, and handling an electric eel or even entering the water wherever these fish are common should be avoided at all costs.
Pythons and boas (anacondas being a kind of boa) are not venomous. They have very sharp teeth to hold on to their prey, but they rely on constriction for the actual kill. This means, they coil around the victim (once they have secured it with their teeth) and squeeze so that the unfortunate animal doesn’t have any space to breathe. Every time the victim tries to inhale, the snake squeezes harder. This deadly “hug” is so powerful that even blood can’t flow. As a matter of fact, death comes usually because of cardiac arrest/stroke, and not asphyxia as was once believed.
Although some smaller snakes (such as king snakes and gopher snakes) use constriction to kill prey, pythons and anacondas are the best known constrictors, and the scariest, too, since these cold-blooded predators have been known to kill and eat humans once in a while.