Electric eels can kill horses, new research confirms

Experiments at Vanderbilt University have proven a 200-year-old observation that electric eels can leap out of water and shock animals to death, a claim originally made by 19th century biologist and explorer Alexander von Humboldt.

Out of water, the high voltage electrical salvo zaps a target directly, intensifying the effect

Historic illustration of electric eels attacking horses, as observed by explorer Alexander von Humboldt. (Vanderbilt University)
Experiments at Vanderbilt University have proven a 200-year-old observation that electric eels can leap out of water and shock animals to death, a claim originally made by 19th century biologist and explorer Alexander von Humboldt.

During a field trip to the Amazon basin in 1800, Humboldt said he saw electric eels leaping out of the water and 
delivering enough voltage to kill a horse. But with no scientific studies on the matter, and no similar observations 
since, many had come to believe that the famous naturalist was exaggerating.

"The first time I read von Humboldt's tale, I thought it was completely bizarre," said Ken Catania, the Stevenson Professor of Biological Sciences at Vanderbilt University, in Nashville, Tennessee, where the recent experiments were conducted. "Why would the eels attack the horses instead of swimming away?"

Validation of story

The answer, according to Catania, is that the eels felt cornered and threatened. A biologist who has been studying eels 
for several years, Catania said he not only validated the original account but found evidence that leaping eels were far 
more terrifying than even von Humboldt realized.

When an eel is submerged, the power of its electrical pulses is distributed throughout the water, freezing its target into 
state of shock, he said. Out of water, the high voltage electrical salvo zaps a target directly through the skin near 
the eel's chin, intensifying the effect.

To visualize it, Catania covered a plastic arm and crocodile head with a conductive metal strip and a network of 
light-emitting diodes (LEDs), which used the voltage supplied by the eels and lit up brightly when attacked.

Illustration of how the electrical circuit formed between an electric eel and its target change during a leaping attack. (Kenneth Catania / Vanderbilt University)

"When you see the LEDs light up, think of them as the endings of pain nerves being stimulated. That will give you an 
idea of how effective these attacks can be," Catania said.

The research was funded by the National Science Foundation and the findings were published in the Proceedings of the National Academy of Sciences this week.