Electric eels’ leaping behavior had been described by Alexander von Humboldt way back in the 1800s. Humboldt claimed to have witnessed a dramatic battle between electric eels and horses in the Amazon. But, Catania says, “No one really necessarily believed it, or if they did, they thought it was just kind of weird.” Whatever they thought, it was more or less forgotten.
To understand the dynamics of the electrical circuit created when an eel contacts another animal, Catania developed an apparatus to accurately measure the strength of the electric current through a human arm when the electric eels leapt in attack. Catania put that apparatus to use with his own arm and a relatively small, and therefore less powerful, eel.
As reported in the new study, the electrical current delivered by the eel peaked at 40-50 milliamps. That’s more than enough to cause a person or animal considerable pain, but not enough to actually hurt them. In a video, one can see Catania’s arm reflexively pull back, an involuntary reaction similar to what would happen if you touched a hot stove.
“It’s impressive that a little eel could deliver that much electricity,” Catania says. Of course, they have good reason as they may encounter crocodiles, predatory cats, and “who knows what else,” he adds. “We don’t know the main driver of the behavior, but they need to deter predators, and I can tell you it’s really good at that. I can’t imagine an animal that had received this [jolt] sticking around.”
The video is definitely squirm-inducing.