Torpedo, the generic and popular name of the electric rays or skates of the family torpe-dinidoe. They were called νάρκη by the Greeks and torpedo by the Latins; the Germans call them Krampffisch, the French torpille, and the English cramp fish and numb fish. The body is. smooth and rounded; the tail short and thick, cylindrical at the end and keeled on the sides; teeth conical, sharp, and crowded; ventral fins immediately behind the pectorals, dorsals generally two and on the tail, and the caudal subtriangular. The electrical apparatus, which has given the name to the family, is arranged in two masses, one on each side of the skull, between this and the base of the pectorals; it is composed of a multitude of perpendicular gelatinous columns or hexagonal prisms, separated by membranous partitions containing a fluid, freely supplied with blood, and receiving very numerous nervous filaments from the par vagum and trifacial nerves. There are about 20 species, arranged in seven genera, in the seas of all parts of the world; the best known are the species of the Mediterranean and the W. coast of Europe, and of the Atlantic coast of North America, all belonging to the genus torpedo (Dum.), in which the mouth is creseentic, the teeth not extending outward beyond the margin of the lips, and spiracles distant from the eyes, with a circular fringe around the opening.
The common torpedo of the Mediterranean (T. marmorata, Rud.; T. Galvanii, Bonap.) is sometimes of a uniform brown, but generally marbled or spotted with darker; it rarely attains greater dimensions than 4 by 2½ ft., or a weight of more than 50 lbs. The spotted torpedo of the same sea (T. ocellata, Rud.; T. narke, Risso) is yellowish red, with one to five large, rounded, grayish blue spots, surrounded by a brownish circle, with a few whitish dots, and grayish white below. One (or both) of these species occurs on the W. coast of Europe as far as Great Britain, and also, it is said, in the Persian gulf and Indian ocean; they feed on small fish, keeping on the mud or sand at the bottom; their flesh is eaten along the Mediterranean. Their electrical apparatus is analogous to the galvanic pile; John Hunter counted 1,200 columns in a very large fish, about 150 plates to the inch. - The American torpedo (T. occidentalis, Storer) attains a length of about 4½ ft. and a width of 3 ft.; it is dark brown above with a few black dots, and white beneath; eyes very small, and spiracles directed outward and a little forward.
In one specimen Prof. J. Wyman estimated the number of plates at between 250,000 and 300,000, about 1,200 prisms in each battery, each 1 to 2 in. in height, and containing about 100 plates to the inch; the interval between the plates was filled with an albuminous fluid, 90 per cent, water, containing common salt in solution; the ganglia from which the par vagum nerves arise are larger than the brain itself, indicating the great nervous power supplied to the battery. - See Electric Fishes, and Lecons sur les phenomenes physiques des corps vivants, by C. Matteucci (Paris, 1847).
American Torpedo (Torpedo occidentalis).