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.

Coral reef fish start their lives as small, transparent larvae. After they hatch, they join a swirling sea of plankton and frequently get dispersed to different reefs due to ocean currents, waves and the wind.

In this study, the scientists did seven years of surveys focussing on the Clark’s anemonefish, measuring how the dispersal of larvae varied over the years and seasonally. They discovered that the larvae dispersal varied immensely on both these timescales.