Electric eels recorded for the first time hunting in packs

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Electrophorus voltai - Electric eel

For the first time electric eels have been recorded hunting in packs and scientists believe that it is an extraordinary discovery. Dr. David de Santana from the Smithsonian National Museum of Natural History said, “Nothing like this has ever been documented in electric eels. Hunting in groups is pretty common among mammals, but it’s actually quite rare in fishes.”

Electrophorus voltai - Electric eel

Electrophorus voltai – Electric eel. Photo: L. Sousa.

Dr. de Santana watched eels in a lake in the Amazon rainforest having got there after a five day boat ride. The eels were observed lying still for most of the day and as twilight arrived the eels, who they believed were solitary, massed together to herd fish into a tight ball until they zapped them with 860 volts of electricity. The study has been reported in the journal Ecology and Evolution. They describe the attack in detail.

They reported that they saw the eels driving tropical fish into a “prey ball” at which point they were attacked. When the prey fish were electrocuted they jumped out of the water. They hit the surface stunned and motionless and were quickly swallowed by the eels. Sometimes opportunistic predators joined in to eat the tropical fish called tetras.

The high voltage discharge of electricity lasts for two thousand’s of a second and it is strong enough to paralyse the prey’s muscles. As the electric eels joined in taking their turn to discharge electricity it spread the load. They say that the eels formed a different subset when they attacked each time.

Each hunting event took about two hours, “and involved 5 to 7 joint high-voltage predatory attacks”. The eels that they observed have the scientific name Electrophorus voltai and are a fairly recent discovery. They discharge 210 V more than any other animal observed so far. The only location where this behaviour has been observed is in the Iriri River in the Amazon rainforest.

It is thought that this rare event takes place because there’s lots of prey with plenty of shelter for such a large number of eels. None of the locals had seen the eels attack like this. This species of eel is up to 8 feet long. Because the locals have not seen it happen before they think it’s a rare event.


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