WASHINGTON - The electric eel, the scaleless Amazonian fish capable of producing 600 volts of electricity which can knock over a horse, uses a electroshock mechanism similar to a Taser, scientists said Thursday.
The eel's electrical impulses briefly paralyse prey by causing muscle contractions, not unlike the electric stun guns used by police.
"I was struck by the similarity between the eel's volley and a Taser discharge," said Kenneth Catania, biology professor at Vanderbilt University and lead author of the study which appeared in the journal Science.
"A Taser delivers 19 high-voltage pulses per second while the electric eel produces 400 pulses per second," he said.
To film the fish's rapid action - the electric eel can strike and swallow small prey in approximately a tenth of a second - Catania set up a high-speed video system running at 1,000 frames per second.
He also carried out a series of experiments to study the fish's mechanism in action.
The eel's electric discharges act on motor neurons and cause strong muscle contractions that allow the eel to control its target prey from a distance.
"It's amazing. The eel can totally inactivate its prey in just three milliseconds. The fish are completely paralysed," Catania said.
However the contractions are brief and the eel must quickly swallow its prey - usually a fish - before it can escape.
The researchers also found that the eels, which see poorly and hunt in muddy waters but are highly sensitive to water movement, sense the location of their prey from the twitching induced by muscle contractions.
Electric eels, which are more closely related to catfish than true eels, have electrocytes inside their bodies - which are electric cells derived from muscle tissue. These biological batteries are found only in few animal species.
Eels and other electric fish have intrigued humans for centuries. Ancient Egyptians used electric marine rays to treat epilepsy, and English scientist Michael Faraday studied eels to understand the nature of electricity.
The eel's anatomy was also a source of inspiration for Alessandro Volta's invention of the battery.
Researchers at the University of Wisconsin-Madison announced several months prior that they had sequenced the electric eel's genome.
Electric eels measure up to eight feet long (2.5 meters) and weigh up to 4.5 pounds (two kilograms).