Shocking!In the annals of 19th century naturalist Alexander von Humboldt are observed an unusual fis

Shocking!In the annals of 19th century naturalist Alexander von Humboldt are observed an unusual fishing method, employed by the native tribes of Calabozo in South America. In slimy waters rimmed with odorous plants dwell the notoriously elusive and agile electric eels. To entice and capture their quarry, the tribes used an unconventionally large bait - horses. The tribes would herd some wild-caught horses into the ditch. The noise and motion would drive the eels out of the slime, where they then - as von Humboldt observed - launched themselves out of the water, pressed their chins against the bellies of the horses, and administered their shocks. The horses would scream and kick, as the native people - using long canes - both captured the eels and prevented the horses from escaping. The raucous and commotion would terrify the eels, which only intensified their charges. Repeated shocks and flailing meant that both horse and eel died from sheer exhaustion. The tribe would then scoop the eels up, the danger eliminated.To modern-day scientists, the whole account seemed ridiculous. No electric eels had been observed ‘leaping out of the water’ to attack. That is, until this year. Biologist Kenneth Catania found that approaching an aquarium housing the eels with a net caused them to pounce. Catania observed that they would “explode out of the water upwards,” and press their chins against the metal handles of the net. Sound familiar? His gloves prevented him from getting shocked, but Catania was pretty shocked anyway, at the idea that a 19th century tale set deep in the South American jungle, viewed with skepticism by most of the scientific community, could indeed be based on truth. You can see the behaviour in action here: https://www.youtube.com/watch?v=7UWgtrCzLw0Furthermore, Catania noticed that the leaps were coordinated with high-voltage pulses, suggesting that the behaviour was defensive as well as offensive. In this way, the eels are able to deliver their electric power directly to the threat, rather than distributing it through the surrounding water as they do normally.Though further research is needed to determine how this behaviour works in a wild context (as well as how predators respond to such attacks), the discovery represents an amazing example of how a relatively simple defensive behaviour is amplified by exploiting the very physics of electricity.VPReferences: http://bit.ly/1UOznK1, http://bit.ly/1WCH49OImage credit: Harum Koh (https://flic.kr/p/pL5LG9) -- source link

More pics about