Electric eels, those perilous predators of South America, can unleash a potent electrical jolt to wallop their hapless prey. But this zap is not used merely to stun other fish.

A new study shows that the eels use it to exert a form of remote control over their victims, causing fish that may be hiding to twitch, thus exposing their location, or inducing involuntary muscle contraction to incapacitate their prey.

"Apparently, eels invented the Taser long before humans," said biologist Kenneth Catania of Vanderbilt University in Nashville, Tennessee, who conducted the research published on Thursday in the journal Science.