Social predation is well known in mammals. This coordination is however rarer in fish. Discover that the fearsome electric eels of Volta (Electrophorus voltai) are capable of launching grouped and devastating attacks, therefore greatly surprised a team of American and Brazilian researchers.
An electric shock of 860 V
“Social predation occurs when groups of individuals work together to find, target and kill larger or more prey“, explain the researchers in a study published on January 14, 2021 in the journal Ecology and Evolution. This tactic saves time and conserves energy: two precious elements in nature. Yet Volta’s electric eels, formidable predators capable of generating up to 860 V during an attack (the natural world record), until now did not seem to be among the followers of social predation. Scientists had previously observed them hunting alone at night, when their prey, diurnal fish, are resting. But in a small lake, fed by the Iriri River in Brazil, the authors of this new study discovered a hundred adult eels. This gathering in itself was confusing.
Several attacks in an hour
The team was not at the end of its surprises: in 2012, it observed for the first time a coordinated hunt of electric eels from Volta. Another expedition in 2014 confirmed that this behavior was not ad hoc. These predators always follow the same pattern: they rest in fairly deep water and then they interact. They then migrate to an area where there are prey, a school of fish for example, then they group them together and throw electric shocks in groups of two to ten. “Preys hit by the electric shocks were seen jumping out of the water and returning to the water surface stunned and motionless, being quickly swallowed by the eelsThe study reports. These electric eels can carry out between five and seven attacks in an hour.
“If you think about it, an individual of this species can produce a discharge of up to 860 volts – so in theory, if 10 of them were to discharge at the same time, they could produce up to 8,600 volts of electricity, remark in a press release Carlos David de Santana, co-author of the study. That’s roughly the same voltage needed to power 100 bulbs.“The coordinated attack is formidable and leaves little chance for the prey.”Nothing like this has ever been documented in electric eels“, welcomes the researcher.