In 1800, Prussian adventurer Baron Alexander von Humboldt explored the Amazon River and claimed he witnessed natives driving horses and mules into the water where they were attacked by leaping electric eels until some of the animals were dead and the eels were fully discharged, whereupon the natives dove in to collect the main ingredient for electric eel stew. Since no one has ever seen this again, von Humboldt’s shocking leaping eel story was considered to be all wet. Not anymore.
Vanderbilt University biologist Kenneth Catania has written his own harrowing account of leaping electric eels in the current edition of the Proceedings of the National Academy of Sciences. A professor of Biological Sciences, Catania studies eels which he keeps in large tanks in his lab. While moving specimens from one tank to another with a metal net (electric eels – metal net – does he have a death wish?), Catania saw what von Humboldt saw (minus the horses) … an eel leaped out of the water, pressed its chin to the net’s handle (eels have chins?) and blasted it with a series of high-voltage pulses. Catania was luckily wearing rubber gloves so he lived to run like hell and get out of the biological sciences business.
Just kidding. Catania did what any good scientist would do – he conducted experiments to recreate and record the behavior for skeptics (and von Humboldt’s poor descendants who have lived in shame ever since). He first found that the electric eels ignore objects that aren’t conductors – makes sense.
He then attached a voltmeter and an ammeter to an aluminum plate (budgets are low for eel experiments) and placed it near the eels, sometimes completely submerged and sometimes partially submerged. The electrical discharge was lower underwater because it was distributed through it – water is a conductor, but a poor one. However, when an eel leaped out of the water to attack the plate, the current traveled directly from chin to metal, then back through the water to the eel’s tail, completing the circuit. Even more interesting, Catania found that the eel’s voltage and amperage increased the higher it leaped from the water.
So von Humboldt’s story was factual. Catania believes the Baron witnessed the eels leaping to attack the horses during the dry season, when there wasn’t much water for the eels to hide in, making them feel cornered and turn aggressive, thus displaying their secret leaping ability.
Unfortunately, he wasn't able to fully recreate the Amazon scenario in the lab with miniature horses. Perhaps he should ask von Humboldt’s descendants for a research grant.