Published December 15, 2014 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2014 Susan Scott
Can an electric eel kill a horse? The question came to me last week after a Vanderbilt University researcher published details about how South American river eels catch fish. The nearly sightless eel sends out two electric pulses that cause a hiding, motionless fish to twitch, revealing its location. The eel then zaps the shuddering fish with 600 volts, killing it for an easy meal.
An excellent short video shows this hunting technique at bit.ly/1vFsrzd.
The report about this odd eel got me wondering how electric eels are related to ocean eels, and that investigation brought me to a website stating that an electric eel can kill a horse.
Really? Any science to that? My search just got longer.
In describing a typical eel, my favorite fish book lists five qualities, and follows it with a whole paragraph of exceptions. That, of course, is the beauty of biology. Species adapt in their own ways to their surroundings, and that often makes lists of characteristic useless.
This is especially true of eels, for which exceptions are the rule. The only thing all eels have in common is that they’re fish with long, snakelike bodies.
To give some order to the wide world of eels, researchers divide them into four families. Three of those — morays, congers and snake eels — are common saltwater species.
Members of the fourth family are called “true” eels. (This statement makes me smile because it sounds as if our eels are lying about their heritage.) These live in fresh water and spawn in the sea.
Depending on the species, lake and stream eels spend six to 12 years in their freshwater homes and then migrate to sea.
To reach their spawning grounds, true eels swim and ride ocean currents, some for more than 3,000 miles. After spawning, they die. Their tiny offspring drift for one to three years before finally reaching coastal waters.
Males prefer to live in estuaries and rivers; females like lakes.
The electric eel is a grand exception to all of the above. Not only is this freshwater fish wired, it breathes air, an adaptation to the muddy, oxygen-poor creeks and rivers the fish calls home.
An electric eel must break the surface every minute or so to take a breath or it drowns.
Only the front one-fifth of an electric eel contains vital organs. The rest of the 7 foot long body is a container for the fish’s battery bank, charged by about 6,000 special cells.
The eel uses low power, about 10 volts, like radar to move around its murky environments.
Electric eels have a category of their own shared with their cousins, South America’s knifefish, also snaky and electric, but much smaller and packing far less voltage.
As I looked for reliable confirmation that an electric eel can kill a horse, I found in another of my textbooks a detailed black-and-white drawing, source anonymous, of several wild-eyed horses flailing in a river loaded with electric eels.
The caption says, “An accurate rendering of electric eels, Electophorus electricus, in an otherwise dramatized setting.”
No mention of the horses.
Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com
©2014 Susan Scott