Electric eels use their ability to shock for more than just stunning an intended prey victim, a study has found; they can also utilize their electric organ to remotely "control" that prey.
With an electrical discharge that can reach 600 volts, electric eels can make the muscles in their chosen prey twitch, either immobilizing it or causing it to reveal where it's hiding by the sudden movement, researchers say.
"Apparently, eels invented the Taser long before humans," says biologist Kenneth Catania of Vanderbilt University, leader of a study published in the journal Science.
In a series of experiments, Catania put eels and fish into tanks to observe the eel's high-voltage hunting technique.
When the eels caught sight of their prey they would release pulses of electricity that capable of immobilizing the fish, pulses that further study proved were directly activating nerves in the fish controlling their muscles.
It is this pulsing action that makes researchers draw a parallel with a Taser, which works by overloading the nerves controlling muscles in the body of the Taser's target.
"I have some friends in law enforcement, so I was familiar with how a Taser works," says Catania. "And I was struck by the similarity between the eel's volley and a Taser discharge. A Taser delivers 19 high-voltage pulses per second while the electric eel produces 400 pulses per second."
Previous research has shown eels emit double pulses, known as doublets, when searching for prey that's out of sight, "usually when they're excited and they know that food is around but can't find it," Catania says.
"It actually turns out that this [doublet] generates very rapid and strong [muscle] contraction" in their prey, causing the fish to "jump" and reveal their whereabouts, he explains.
The eels, very sensitive to the movement of water, can detect the motion that's caused by the "jump."
Electric eels, found throughout the basins of the Amazon and Orinoco river in South America, can reach 6 feet in length.
The ability to deliver an electric shock, with a voltage five times that of an electrical outlet in the U.S. -- is contained within organs made up of specialized cells known as electrocytes that turn those organs into biological batteries.
Those batteries make the electric eel one of he most amazing creatures he ever observed, says Catania, who has spent much of his career studying animals with extreme abilities and adaptations.
"After all, they can generate hundreds of volts -- that by itself is incredible," he says. "But to use that ability to essentially reach into another animal's nervous system and activate their muscles is a pretty good trick."