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The electric eel is famous for its ability to deliver a shocking jolt. Turns out these electric fish sometimes leap out of the water to do it. One scientist has been exploring why the eels jump up by letting an eel repeatedly shock his arm. NPR's Nell Greenfieldboyce reports.
NELL GREENFIELDBOYCE, BYLINE: Ken Catania is a neurobiologist at Vanderbilt University. He had some electric eels in his lab, and he noticed something strange. Whenever he tried to fish them out with a net, the eels would leap out of the water to attack it.
KEN CATANIA: Electric eels in my experience had never done something like that where they come out of the water. And they did it in a very directed way.
GREENFIELDBOYCE: What's more, he had electrodes in the water so he could listen to their electrical output through a speaker.
(SOUNDBITE OF SPEAKER BUZZING)
CATANIA: So I knew when they were attacking the net this way they were simultaneously giving off a high-voltage discharge. So that clue led me to think, well, maybe this is sort of a defensive behavior.
GREENFIELDBOYCE: He started to explore this using a metal plate rigged up to a device that could register the jolt delivered by an attacking eel.
CATANIA: As the eel came up out of the water, the voltage that I recorded increased in proportion to height. So the higher they got, the higher the voltage. And that suggested why they might be doing this.
GREENFIELDBOYCE: By leaping out of the water, the eels could send more of the shock directly into the target. Catania wanted to understand what this would do to a living target, so he let a small eel repeatedly zap his arm as he gripped a device that measured the strength of the electric current.
CATANIA: If you work around electric eels a lot, occasionally you're going to get shocked anyway. So I kind of knew what I was in for. Sort of like an electric fence sensation a few times.
GREENFIELDBOYCE: In the journal Current Biology, he says this small eel delivered around 50 milliamps. But from that he could estimate the power of, say, a leaping 5-foot-long eel, which would deliver a serious jolt.
CATANIA: Very much like a law enforcement Taser.
GREENFIELDBOYCE: Catania's research has electrified the electric fish community. Bruce Carlson is a biologist at Washington University in St. Louis. He says even though these eels have been a curiosity for centuries, no one realized their electrical behavior was so sophisticated.
BRUCE CARLSON: Really I think the community was kind of naive and just thought that, well, it's really simple. The eel generates up to six or 700 volts of electricity, so it just shocks whatever gets near it and it's as simple as that. And there's really nothing interesting to study here.
GREENFIELDBOYCE: There was one 19th century account of electric eels leaping up to attack horses. James Albert is a biologist at the University of Louisiana. He says no one knew what to make of that weird anecdote.
JAMES ALBERT: But now there's some evidence for it for the first time. This apparently is a natural behavior of the animal.
GREENFIELDBOYCE: He says eels can end up in shallow pools during the dry season, but it's hard to imagine what might try to eat them.
ALBERT: A large cat perhaps. I don't know. What would go after an electric eel?
GREENFIELDBOYCE: Because whatever it was would be in for a real shock. Nell Greenfieldboyce, NPR News.
(SOUNDBITE OF MGMT SONG, "ELECTRIC FEEL")
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