An electric eel (Electrophorus electricus). Credit: Doug Letterman (flickr). Image may have been cropped.

Researchers have discovered that electric eels use electricity as a sort of remote control on the fishes’ muscles.

Kenneth Catania of Vanderbilt University in the USA watched some hungry eels and fish in fish tanks. When the eels saw the fish, they released pulses of electricity – up to 600 volts – and the fish froze in position, unable to escape. Professor Catania wondered how the eels `froze’ the fish.  He discovered that the eel’s electric pulses send a `keep still’ message to the fishes’ nerves that control their muscles. They seem to copy the normal electrical pulses the fish nerves use to tell muscles what to do.

The eels have two other types of pulses.  A separate zap makes nearby fish have twitchy muscles, which might help reveal hiding fish. The eels also use low-voltage pulses as a kind of sonar to sense what else might be around them in the water.