ELECTRIC EEL (Electrophorus [Gymnotus] electricus), a South American fish which, in spite of its external similarity, has nothing to do with the eels (Anguilla), but belongs to the order Ostariophysi, which includes the carps or Cyprinidae and the cat fishes or Siluridae. The dorsal and caudal fins are rudimentary or absent, and the anal long, extending from the anus, which is under the throat, to the end of the body.
Electrophorus is the only genus of the family which possesses electric organs. These extend the whole length of the tail, which is four-fifths of the body. They are modifications of the lateral muscles and are supplied with numerous branches of the spinal nerves. They consist of longitudinal columns, each composed of an immense number of "electric plates." The posterior end of the organ is positive, the anterior negative, and the current passes from the tail to the head. The maximum shock is given when the head and tail are in contact with different points on the sur face of some other animal. E. electricus attains a length of aft. and the thickness of a man's thigh, and frequents the marshes of Brazil and the Guianas. When this natural battery is discharged in a favourable position, it is sufficiently powerful to stun the largest animal. These fish are eaten by the Indians, who are said by Humboldt first to exhaust their electrical power by driving horses into the ponds. The strength of the shock varies with the size and condition of the fish. Several other fish possess the power of discharging electricity but to a lesser degree. The Afri can genus Malapterurus of cat-fish of which the best known is the raash (M. electricus) of the Nile and other large tropical rivers ; in habit it is sluggish and the flesh is edible. The shock passes from head to tail.
Less developed than in either of the above, some i 5 species of electric rays or torpedoes also have the faculty of electrical dis charge ; the most famous of these is Torpedo marmoratus of southern Europe. The discharge passes from below upwards.
Electrical power has been independently acquired in each of these groups.