A powerful creature

The electric eel can let loose electric jolts of up to 500 jolts - enough to cause serious harm to an adult human.

By STUART WINER
Electric Eel 311 (photo credit: Tamar Raviv)
Electric Eel 311
(photo credit: Tamar Raviv)
In a tank at the Wet Side Story exhibit at the Jerusalem zoo are three examples of an animal that never ceases to fascinate both young and old. Electric eels are the stuff of legend and often comedy, too, with their ability to produce a strong electric shock, the butt of many a cartoon joke. However, not only are electric eels not really eels, but they also breathe air.
Electric eels, Electrophorus electricus, belong to the group of electric fish that can either detect or produce the invisible electric fields that surround electrically charged objects. Fish such as sharks and catfish can detect electric fields as well, but what makes the Electrophorus unique is its ability to generate an electrical current from special muscles that make up two-thirds of its body length.
The eels live in the murky swamps of South America and are nearly blind. To compensate forthat, they produce small electrical pulses to navigate and detect prey. When the eel finds its target or if it is threatened by an attacker, it can let loose with a much larger electric jolt that either stuns or kills its prey. The charge can be as much as 500 volts and could easily cause serious harm to an adult human.
Zookeeper Natasha Weinstein knows first-hand just how quick the eels are to use their special powers. As she was cleaning out their tank one day, one of the eels slithered close to her bare hand. Whether threatened by the invading hand or perhaps looking for a quick meal, the fish surprised
Weinstein with a nasty jolt. The fact that she was standing on a wooden platform may have saved her from serious injury. Since then, when cleaning the eels’ tank, keepers at the zoo wear electrically insulated gloves rated up to 1100 volts.
Another curious aspect of the eels, which can grow to be up to two meters in length, is the way they breathe. Unlike most fish, they have no gills but rather a network of blood vessels around the face and inside the mouth that absorbs oxygen from the water. However, this alone is not enough, and the fish regularly swim to the surface to take a gulp of fresh air.
At the zoo, it is unclear what sex the three eels are, as it is difficult to find any clues on a fish that is long, smooth and mainly featureless. When breeding in the wild, the male eel builds a nest using his saliva, and the obliging female lays her eggs in it, up to 17,000 at a time. Should the zoo’s eels reproduce on that scale, they may yet have another shock in store for their keepers.