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. The study reveals precisely what an eel's zap does to its victim. In laboratory experiments, Catania showed how the electrical discharges remotely activate the prey's neurons, or nerve cells, that control the muscles. While hunting, the eels periodically give off two high-voltage pulses separated by a 2 millisecond pause, causing a massive involuntary twitch in nearby hidden prey, the study found. The eels, highly sensitive to water movements, can detect motion caused by the twitch, learning the other fish's location. The eel then delivers a full blast of a longer, high-voltage shock to immobilize the prey through involuntary muscle contraction -- much like a Taser -- enabling easy capture.
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