Electric eels are able to deliver shocks to prey in a manner similar to tasers, a new study reveals. Electric eels can deliver electric shocks up to 600 volts - powerful enough to cause a horse to drop to the ground in pain. These are the most powerful electrical shocks of any fish in the animal kingdom.
Like a remote control, these shocks can also be delivered from several yards away, new research from Vanderbilt University has discovered.
Electrical shocks can not only kill or stun prey, but can also cause prey animals to twitch, revealing their hiding spots to hungry eels.
Electrophorus electricus was observed in a large tank, using a high-speed camera, as the creatures hunted prey such as koi. The cameras, recording action at 1,000 frames per second, took high-quality video of the attacks. Researchers also carefully noted electrical discharges from the eels, and noted associated muscle spasms from the shocks.
As fish swim past the eels, the predators can release a high-voltage shock, that travels through the water to the prey animal. This causes muscles in the animals to contract, freezing the prey, preventing the animal from swimming to safety, similar to the action of a taser. When koi and other target fish were injected with a drug preventing communication between muscles and nerves, contraction was prevented in the event of attacks, researchers discovered. This shows electricity acts on motor neurons in the fish, the first time such a specific effect has been observed.
When electric eels observe a prey animal suddenly cease movement, the eels release two or three high-voltage blasts, which cause target fish to twitch. This effect was measured by studying movements of paralyzed fish placed at the bottom of the tank, as electric eels carried out attacks on the prey. Once the eels detect movement from the target fish, the predator can begin its strike within one-fiftieth of a second.
"It's a fascinating example of evolution in action. The eel isn't just applying a voltage to the water and hoping everything dies. It's a very specific behavior that's obviously been acted on by selection to be refined," Jason Gallant of Michigan State University said.
Eels in the study were only about six inches away from their prey in the tank where the study was conducted.
Kenneth Catania, a biologist at Vanderbilt University recorded the attacks and investigated the effects of blocking nerve signals. He believes the ability to deliver shocks may have initially developed as a means of locating prey.
"Now that we know what the mechanism of the eel's attack is, it's definitely easier to ponder how it evolved," Catania suggested in a press release.
Study of targeting abilities by eels using electrical shocks was detailed in the journal Science.
