Electric eels are generally thought to be solitary hunters, but this may no longer be accurate.
Zoologist Douglas Bastos from the National Institute of Amazonian Research in Manaus, Brazil, and his team have captured video footage of Volta’s electric eels hunting in groups of more than 100.
In the footage, the eels encircled shoals of tetra fish to form a “prey ball”, which they herded toward shallower waters. Then, two to ten of the eels swam closer to the ball to deliver jolts of electricity. The synchronised charge is so powerful that some of the fish are blasted out of the water. Stunned, they fall back into the water, and are consumed by the eels.
This behaviour, filmed at a small lake on the banks of the Iriri River in Brazil, forms the basis of a paper that is recently published in the journal Ecology and Evolution. Bastos is the lead author of the paper.
In a Live Science article, zoologist David de Santana, from the Smithsonian National Museum of Natural History in Washington, D.C., said, “It's really amazing to find a behaviour like that with eels that are 2.4, 2.5 metres long."
Although hunting on its own is less “productive”, the team believes that such group hunting behaviour as seen in the footage is uncommon, and likely occurs only under certain circumstances, like in locations with lots of prey and where there is long-term shelter for multiple eels.