Electric Eels Sandwich Prey to Double Electric Shock

An electric eel can double the strength of its electric field by sandwiching prey between its head and tail. Kenneth Catania, Vanderbilt University

Electric eels can emit up to 600 volts of electricity to kill fish and crustaceans, or cause a nasty jolt to a bigger beast—a person, say. But if faced with a particularly large or recalcitrant fish, they have a special trick: They can bend their bodies and deliver a sort of electric sleeper hold on the unlucky prey.

Kenneth Catania, a neurobiologist who studies animal sensory systems at Vanderbilt University, noticed that when attacking certain larger prey, electric eels sandwiched the animal between their heads and tails. He decided to figure out what exactly was going on. As detailed in a study published today in the journal Current Biology, Catania discovered that this maneuver allows the predator to more than double the strength of the electric field applied to the prey.

The electric eel, which is actually a fish with the scientific name Electrophorus electricus, emits electricity via a positive pole in its head and a negative pole in its tail. Placing prey between them increases the intensity of the shock, according to Catania.

"Historically, electric eels have been viewed as unsophisticated, primitive creatures that have a single play in their playbook: shocking their prey to death," Catania said in a statement. "But it turns out that they can manipulate their electric fields in an intricate fashion that gives them a number of remarkable abilities."

Catania showed in a study last December in the journal Science that the fish can send out low-voltage shocks to cause their prey to twitch and reveal its location if it is, say, hiding in the mud. The eel then switches to "stun" mode, sending out as many as 400 pulses of electricity in a second that causes the prey's muscles to contract and become immobilized, before the eel strikes and eats it.