last updated June 1st,
and is permanently morphing...
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electric eel noun
A long, eellike freshwater
fish (Electrophorus electricus) of northern South America, having organs
capable of producing a powerful electric discharge.
Electric Fish, common name
for several unrelated fishes that emit electrical discharges. The organs
adapted for this purpose consist of groups of highly compact nerve endings
concentrated in the tail. Discharges are emitted by electric fish to stun
their prey while hunting; they are also emitted in self-defense, in the
detection of prey and obstacles, and in navigation. Electric fish must
rest after making numerous discharges in a short interval in order to replenish
The most important electric
fishes are the electric eels (Electrophorus electricus), the electric catfish
(Malapterus electricus), and the electric rays, of which there are several.
The most powerful discharge is emitted by the electric eel found in certain
South American rivers. This electric eel can stun large animals with its
Scientific classification: The electric eel makes
up the family Electrophoridae of the order Gymnotiformes. Electric catfishes
make up the family Malapteruridae of the order Siluriformes. Electric rays
make up the family Torpedinidae of the order Rajiformes.
The adult Electric Eel has enough electrical power
in them that could power a house of about twelve hundred square feet.
Adult electric eels 5ft to 7ft long produce enough
electricity -- 600 volts -- to stun a horse.
To understand the answer
to the electric fish puzzle,
we must restrict the discussion to those fish with active electric sensing
systems. This group includes electric eels, South American knife fish,
and African elephant snout fish. All of these have evolved, in a remarkable
instance of parallel evolution,
the capability of generating pulses
of electricity. These pulses (up to 1,000 per second) radiate through the
Prey and other nearby objects distort these oscillating
fields. Electroreceptors on the fish and a sophisticated data processing
system convert the field distortions into an "image" of the surroundings.
M. and S.J. Lannoo, of Ball State University, have watched the black ghost
knife fish, which plies murky Amazon waters, approach likely prey tail
first. Swimming backward using an elongated belly fin, the knife fish slowly
cruises past its potential victim. If the electrical image looks appetizing,
the knife fish grabs its dinner with a forward lunge as it appears in front
"The researchers suggest
that the fish swims past objects in order to scan them with its electroreceptors.
This is the only way the fish can identify prey because an electric sense
cannot be focussed like an eye. But if the fish carried out its scan by
swimming forwards, the prey would end up at its tail. The fish must swim
backwards to be in a posi- tion to eat the food."
(Day, Stephen; "Why Do Electric
Fish Swim Backwards?" New Scientist, p. 13, April 17, 1993.)