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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?"
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.
"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.
(Reporting by Ben Gruber; Editing by Bill Rigby)
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