USA Today -- Electric eels can jump out of the water to attack ..................................
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Electric eels can jump out of the water to attack
By Mary Bowerman,
USA TODAY Network
8:21 a.m. EDT
June 7, 2016
(Photo: Courtesy of Kenneth Catania / Vanderbilt)
New research reveals that electric eels can spring out of the water and administer powerful electric shocks to would-be predators.
Electric eels will attack large, partially submerged objects by raising up out of the water and zapping perceived threats, according to a study published this week in the journal Proceedings of the National Academy of Sciences.
The research lends credibility to a legendary account by 19th-century explorer Alexander von Humboldt, who said he witnessed electric eels leaping from the waters of the Amazon and shocking horses.
Vanderbilt University biologist Kenneth Catania, who lead the study, said in a statement that many were skeptical of von Humboldt’s account. In part, because in the 200-some years since von Humboldt shared his experience, there have been no similar scientific reports of eels acting similarly.
“The first time I read von Humboldt’s tale, I thought it was completely bizarre,” said Catania. “Why would the eels attack the horses instead of swimming away?”
Catania said he discovered that eels act “even more dramatically than von Humboldt described,” by accident, while transferring eels he was studying from one tank to another.
While using a net with a metal rim handle to transfer the eels, he noticed that many of the eels stopped trying to dodge the net and instead went into attack mode, rising out of the water, and plastering their chins to the handle, “all while generating a series of high-voltage pulses.”
Catania notes that luckily he was wearing rubber gloves, so he didn’t get shocked by the eels.
To test what was happening, Catania placed a conductive rod attached to an aluminum plate partially into the aquarium water, and measured the strength of the electric pulses the eels produced as they jolted the object.
Catania found that when an eel was submerged in the water, the power of its electrical impulse traveled though the water and was much weaker, but when the eel extended out of the water, the jolt of electricity was distributed from its chin directly to the believed threat.
“This allows the eels to deliver shocks with a maximum amount of power to partially submerged land animals that invade their territory,” Catania said. “It also allows them to electrify a much larger portion of the invader’s body.”
To illustrate just what this tactic can do to a perceived threat, Catania covered a plastic alligator head with a conductive metal strip and LED lights.
“When you see the LEDs light up, think of them as the endings of pain nerves being stimulated," Catania said. "That will give you an idea of how effective these attacks can be."
Catania notes that in the experiment, the eels tended to attack more often when the water in the tank was low, suggesting that the "shocking leap" behavior is used to protect themselves during the dry season in the Amazon, when they are vulnerable.
Follow @MaryBowerman on Twitter.
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