A recent email inquiring if an electric eel can kill a person jolted my memory and I recalled an encounter I wrote about several years ago.
I was 11 years old, behind the scenes at the Fort Worth Zoo with a friend and the zoo’s director. “Go ahead,” said the director, “see if you can pick it up. It’s pretty slippery.” I eyed the 12-inch eel and decided to accept the challenge.
Reaching into the small aquarium, I put one hand in front of the snout of the dark gray animal with the yellow belly as it swam away and then lifted it up from below. That’s when I got the shock of my young life. Literally. I had just grabbed an electric eel, to the amusement of my audience of two. A little zoo and aquarium humor at play.
Electric eels belong to the family of knifefishes that inhabit the American tropics. Knifefishes have special organs that build up electrical potential and produce currents that they use to communicate, much the way birds use sound. In essence they talk to each other.
A knifefish can distinguish between its own species and others; it can even determine the sex of another individual of its own kind by the electric waveform generated.
Some species are capable of using their electric receptors to discriminate between individuals of their own species by the fine details of the electrical signature, which varies subtly from one individual to another in a manner perceptible only to another knifefish.
Among the knifefishes, the electric eel, with its impressive super-powers, is unquestionably the top gun. Most knifefishes generate no more than a few millivolts of electricity. The electric eel, with its thoroughly appropriate scientific name, Electrophorus electricus, can knock your socks off by delivering more than 600 volts.
When one of these large eels sends out an electric waveform, everybody listens.
An electric eel can deliver a discharge merely by touching a victim, whether it be a prey animal being subdued, a would-be predator or some other threat being dispatched. Although powerful, the shock would not likely be lethal to a healthy adult human. But the bigger the eel the stronger the potential impact.
The one I grabbed as a kid was small and delivered a shock well below that of standard 120-volt house current. But electric eels can reach more than 8 feet in length, and when large ones attack, they can stun a full-grown horse.
In fact, an encounter between horses and electric eels was addressed by Kenneth C. Catania of Vanderbilt University in a well-designed research study published in the Proceedings of the National Academy of Sciences.
Although his research was focused on electric eel “predatory behavior and sensory abilities,” he resolved a 200-year-old conundrum about whether a story told by Alexander von Humboldt, an early naturalist, was true. The explorer had related a story of horses being used in 1800 in an unusual fashion to capture large electric eels in the floodplain of the Orinoco River.
As Catania explained it, horses were herded “into a pool containing electric eels, provoking the eels to attack by pressing themselves against the horses while discharging.” When the eels had exhausted their electrical charges, they “could be safely collected.”
Understandably, many scientists have considered von Humboldt’s story to be an exaggerated account about eels having the capability to jump up out of the water and shock a perceived threat. Catania offers convincing evidence that the story has credence.
He found that when threatened by a much larger animal, an electric eel will attack, launching itself from the water and using its chin to discharge “high-voltage volleys.” The effort leaves them temporarily unable to deliver another charge.
Considering von Humboldt’s account of how horses fell down after being stunned by the electric charges delivered by the big eels, I’m glad the one I grabbed was a little tyke.
Whit Gibbons is professor of zoology and senior biologist at the University of Georgia’s Savannah River Ecology Laboratory. If you have an environmental question or comment, email ecoviews@gmail.com.
