14 September 2017
Andrew Masterson
Andrew Masterson is a former editor of Cosmos.
Electric eels have evolved to deliver stronger and stronger shocks, as well as refining methods to increase their painful efficiency, research in the journal Current Biology shows.
A paper by Kenneth Catania of Vanderbilt University in Nashville, Tennessee, US, reveals that the eel (Electrophorus electricus) can rise out of the water and connect with an animal to deliver a high intensity shock. Catania, who has been on the receiving end of several such shocks, likened the experience to being stunned by a Taser.
Initiating the jolt while in the air increases its intensity because the electricity does not dissipate like it does when travelling through water. Catania measured the current at 40–50 milliamps – more than enough to cause severe pain and breathing difficulties in humans, although well beneath the likely fatal threshold of 100 milliamps.
The rearing behaviour indicates that the intent of the flying shock is defensive – repelling a potential attacker – rather than predatory.
In research published in 2015, however, Catania showed that even when hunting, electric eels do not just rely on brute shocks to capture their food. In a study, also published in Current Biology, he demonstrated that an eel will surround its prey, manipulating it until it makes simultaneous contact with the eel’s head and tail, then send a jolt right through it.
“We’ve known these animals give off a huge amount of electricity, and everybody thought that was really amazing,” he says. “But they aren’t just simple animals that go around shocking stuff.”