Electric Eel

Named for the electrical charge it releases to stun its prey and enemies, the electric eel can generate up to 800 volts of electricity, enough to kill an adult human.

While all living cells generate electricity, the electric eel arranges about 6,000 of these specialised power cells (called electrocytes) in a series, allowing accumulation of voltage. The cells store power like tiny batteries. When the eel is threatened or attacking prey, these cells discharge simultaneously.

Why, then, does the eel itself not get shocked?

Eels live in water. A large part of the short-lived current (around 2 milliseconds) zips by the vital organs in the eel’s body and is conducted away into the water, electrocuting the eel’s prey in the process. A prey 10 times smaller in length than an eel is about 1,000 times smaller in volume. Though the current received by its prey is only a small portion of the total current generated, it is overwhelming in terms of proportion.

The electric eel is a knifefish and is more closely related to catfish and carp than to other eels. It cannot be kept with other fish as it will shock or eat them.

As it makes its home in the muddy bottoms of rivers, it electro-navigates its way around rather than depend on its bad eyesight. The water they live in often has a very low concentration of dissolved oxygen. Though they have gills to take in dissolved oxygen, they surface frequently for air — 80% of their oxygen intake is obtained this way. Their mouth is lined with folds, which are packed with blood vessels to breathe atmospheric air.

Electric eels reproduce during the dry season. The females lay between 1,200 and 1,700 eggs, which are deposited in a well-hidden nest made of saliva, built by the male. Males stay on guard, defending their nest and the fry vigorously until the rainy season begins.

This parental care may be due to increased food competition and potential for predation during the dry season. Juveniles feed on small invertebrates while newly-hatched fry will eat the unhatched eggs around them.