Electric eels probably wouldn't make most people's list of the world's most devious predators -- but they should. According to a new study, eels manipulate basic physics to double the charge exerted on their toughest prey. The remarkable science trick was described for the first time in a study published Wednesday in Current Biology.
Here's the deal: Electric eels (which are actually a type of fish) have long bodies full of special cells called electrocytes -- cells that store electricity that the animal can discharge when threatened. Electric eels can give off up to 600 volts, which is five times the voltage found in a standard wall socket in the United States.
But it turns out they can increase the charge the inflict on their prey without actually giving off more electricity -- simply by doubling up their bodies.
When faced with bigger prey, electric eels start with a bite, then curl their tail around so that it touched the prey opposite from the electric eel's mouth. This presses the prey's body directly between the positive and negative poles of the electric eel's body. By changing the configuration of the electrical field, the eel more than doubles the charge being inflicted.
Vanderbilt University biologist Kenneth Catania, who discovered the strange mechanism, has actually made several groundbreaking findings on electric eels in the past few years: He recently published a study showing that electric eels use their predatory electrical pulses as a sort of radar, and in a previous paper he showed that certain pulses attack neurons directly, forcing prey to twitch out of hiding and into the open.
But this latest finding is his favorite.
"It’s straight out of intro physics, it's as if the electric eels took a class in physics and said, 'hey, we've got a handle on this,'" Catania told The Post. "That’s what’s beautiful about it."
In studying this ingenious behavior -- which he did by wiggling dead fish full of electrodes in front of hungry electric eels -- Catania found that the curled position causes electrical pulses so strong and fast that they cause total muscle fatigue in the prey.
"The eel is running the prey’s muscles involuntarily at this high rate over and over again until they can’t contract anymore," Catania explained. "I think it's analogous to poisoning the neuromuscular systems."
In a way, he said, the electric eel is acting an awful lot like a venomous snake.
"Lots of snakes deal with prey by inactivating their muscles chemically," he said. "The electric eels are inactivating muscles with electricity, which is just so crazy."