Electric Eels Use Their High-Voltage Shocks to Locate Prey

Electric eels use special electricity-emitting organs to stun their prey, and a scientist recently discovered they use these same mechanisms to locate their food in the dark. A study published this week in Nature Communications [PDF] illustrates how these nocturnal creatures use energy fields to “electrolocate” their prey as well as paralyze them with a charge of up to 600 volts.

Ken Catania, a neurobiologist at Vanderbilt University, conducted a series of laboratory experiments in which he observed this shocking behavior in action. He presented the eels with anesthetized fish, blocked from the predators' electroreceptors with plastic bags. When Catania forced the fish to twitch with an electrode, the eel emitted its electrical attack. But after that, it was stumped. The eel lunged towards the movement in the water but made no attempt to devour the fish.

Things got even more interesting once Catania introduced an electrically conductive carbon rod to the tank. After releasing its charge, the eel initially moved towards the direction of the fish only to change its mind and dart towards the rod instead, wherever it had been placed. When Catania moved the rod onto a rotating wheel and removed the fish from the tank entirely, the eel was further confused, writhing to suck up the rod that it perceived to be its prey.

This behavior suggests that electric eels are able to simultaneously use their electric charge as a predatory attack and a tracking system. Catania published a separate study in Science last year that showed how an electric eel’s shock can stimulate its prey’s motor neurons and cause involuntary muscle spasms. After a couple of electric volleys, the helpless fish will have revealed its location before the eel goes in for the kill. The eel sucks up the prey within milliseconds of the attack, which we now know it does by using its high-voltage charge to pinpoint its exact location.

These recent findings place electric eels in the same league as bats, sharks, and other creatures who use a type of “sixth sense” to locate their prey. Sharks and rays can sense the electric fields emitted by other creatures, while bats and some whales use sonar to detect reflected sound. But eels are the only creatures whose locating sense doubles as a weapon, making them even more awesome (or terrifying) than we previously realized.