EELS CAN DELIVER A POWERFUL PUNCH
24 , 2016
recently read a scientific paper by Kenneth C. Catania (Vanderbilt University)
that jolted my memory back to a 2-second time period I had not thought
of in decades. I was behind the scenes in the Fort Worth Zoo with a
friend and the zoo's director, who said, "Go ahead and see if you
can pick it up, but it's pretty slippery."
the challenge, because I was young and was pretty sure a foot-long eel
couldn't be that hard to hold on to. I reached into the small aquarium,
putting one hand in front of the snout of the dark gray animal with
the yellow belly as it swam away and then lifting it up from below.
when I got the shock of my life. I had just grabbed an electric eel
to the amusement of my audience of two. A little zoo and aquarium humor
eels may sound like a comic book fantasy but they belong to the knifefishes
that inhabit the American tropics. Knifefishes have special organs that
build up electrical potential and produce currents used as a means of
communication the way birds use sound. In essence they talk to each
can distinguish between its own species and others and can even determine
the sex of another individual of its own kind by the electric waveform
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 to another knifefish.
eel is the superhero among the knifefishes with their already impressive
super powers. Most knifefishes can generate no more than a few millivolts
of electricity. But the electric eel, with its thoroughly appropriate
scientific name, Electrophorus electricus, can knock your socks
off by delivering more than 600 volts! When an electric eel talks, everybody
eel can deliver a discharge directly by touching a victim, whether it
be a prey animal being subdued, a would-be predator or some other threat.
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 6 feet in length, and when large ones attack, they can stun
a full-grown horse.
an encounter between horses and electric eels was addressed by Catania
in his well-designed research study published in the Proceedings of
the National Academy of Sciences.
his research was focused on electric eel "predatory behavior and
sensory abilities," he resolved a two-centuries-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.
explained it, horses were herded "into a pool containing electric
eels, provoking the eels to attack by pressing themselves against the
horses while discharging."
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.
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
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.
you have an environmental question or comment, email