In the forest pools, as well as in the marshy ponds and slow-flowing
rivers of the Llanos, numbers of huge serpentlike heads may be seen
bobbing above the surface; or a huge, thick-bodied, yellow, snake-like
creature may be caught sight of gliding through the water. It is the
gymnotus electricus, or electric eel,--one of the many curious
inhabitants of this region,--from two to five, and even eight feet in
length. Though really a fish, it resembles the eel, but is stouter in
its proportions. It is nearly equal in thickness throughout. It has a
rude, depressed, and obtuse head, and a compressed tail. So great is
the electric power it possesses, that when in full vigour it is able to
kill the largest animal, when it can unload its electric organs in a
favourable direction. All other fish, knowing by instinct the deadly
effects of its stroke, fly from the formidable gymnotus. When fish are
struck, or any animals which enter the pools inhabited by gymnoti--to
drink, or cool their bodies, heated by the burning sun of the Llanos--
they become stupified, and thus easily fall a prey to the electrical
tyrant.
The natives of Venezuela employ a cruel mode of catching the creatures,
which, notwithstanding their nature, they use as food. Placing but
little value on mules and horses, they collect a number of these
animals, and, armed with harpoons and long slender rods, drive them with
shouts towards a pool inhabited by gymnoti. The noise of the horses'
hoofs and the men's shrieks make the fish issue from the mud, when the
huge, hideous creatures swim on the surface of the water, and crowd
under the bellies of the horses and mules. Some of the Indians climb
the trees; others stand round the margin, urging forward the unfortunate
animals, and preventing them from making their escape. The fish defend
themselves by frequent discharges of their electric batteries. At first
they seem likely to prove victorious. Some of the quadrupeds sink
beneath the violence of the invisible strokes which they receive from
all sides, and, stunned by the force and frequency of the shocks,
disappear under water; others, with their manes erect and eye-balls wild
with pain, strive to escape the electric storm which they have aroused,
but are driven back by the shouts and long whips of the excited Indians.
The livid, yellow eels, like great water-snakes, swim near the surface
and pursue their enemy. After the conflict has lasted a quarter of an
hour or so, the mules and horses appear less alarmed. They no longer
erect their manes, and their eyes express less pain and terror. The
eel-like creatures, instead of advancing as at first, swim to the shore,
when the Indians attack them with their harpoons, and by means of a long
cord attached to it, jerk the fish out of the water, without receiving
any shock, as long as the cord remains dry.
Such is the description given by Humboldt, a witness of the
extraordinary scene. The employment of their electric powers is
evidently spontaneous, and exhausts the nervous energy. Like voluntary
muscular effort, it needs repose, and the creatures require an abundance
of nourishment and rest before a fresh accumulation of electricity is
produced.
In the dry season they form deep circular holes for themselves in the
mud of water-courses, and marshes which remain filled with moisture, and
they are thus able to support existence in their usual localities, while
alligators and turtles have to retire to the larger pools or rivers. In
the shallow ponds of the forest they are easily driven out with long
poles.
Bates amused his native companions, who had thus caught some of the
creatures, by showing them how the electric shock could pass from one
person to another. They joined hands in a line, while he touched the
biggest and freshest of the animals on the head with the point of his
hunting-knife. He found, however, that the experiment did not succeed
more than three times with the same eel when out of the water, for the
fourth time the shock was scarcely perceptible.
The limbs even of the strongest man are benumbed, and he is struck down
helpless, by a discharge from the battery of the gymnotus. The organs
which produce this curious electrical effect are placed along the under
side of the tail. They may be compared to a series of columns inclosed
in a thin membrane packed closely together, which, consisting of a
series of fiat discs, may be imitated by placing a number of coins with
their discs parallel to each other, and with a bladder between each,
separated by a gelatinous substance. These columns are technically
called septa; and La Cepede calculates that two hundred and forty
transverse membranes are packed in each inch, thereby giving to an
electric eel eight feet in length an organ cavity of two hundred and
forty-six square feet--an enormous extent, as may be supposed, of
electricity producing surface. The whole apparatus is supplied with
nerves which run through the entire length of the body.