The Electric Eel—An Engineering Marvel
Horses that were being driven across a stream in South America wildly rose up on their hind legs and plunged into the water. Why?
They had been subjected to severe shocks from electric eels. One eel may measure as much as 8 feet (2.4 m) in length and nearly one and a half feet (0.5 m) around. Experiments have shown that the current generated by an electric eel is strong enough to make a number of 100-watt bulbs flash.
How does the electric eel produce such a strong current? There are three current-producing organs that occupy about 40 percent of its body. Each cell of the current-producing system is designed in such a way that there is a concentration of negatively charged ions inside and positively charged ions outside. The resulting electrical potential is quite small. However, since some 6,000 to 10,000 of these cells are linked together in one column, the combined voltage may be over 500. Additionally, there are about 70 columns, arranged in parallel on each side of the eel’s body with an output of approximately a one-ampere current.
Two features of design have been discovered that make a simultaneous electrical discharge possible. The nerve conductors of differing lengths also vary in thickness. The thinner the nerve conductors are, the slower the brain’s discharge signal will reach the cells. So the nerve conductors leading to the most distant parts are the thickest. Then, too, the shorter nerve conductors have a delaying mechanism that prevents a premature electrical discharge.
The electric eel cannot be harmed by its own current. With the exception of two membranes that make it possible for the electric current to be discharged into the water, the rest of the thick skin serves as an ideal insulator. The linkage of the electric cells is such that the current cannot flow to any other parts of the eel’s body.