Note:  Do not rely on this information. It is very old.

Electric Fishes

Electric Fishes are those furnished with peculiar muscular organs, capable of accumulating electricity and communicating it in the form of shocks to other animals, for the purpose of killing or stunning their prey, or as a means of defence against the attacks of their enemies. Professor Huxley describes these organs as being always composed of nearly parallel partitions of connective tissue, enclosing small chambers containing cellular structures termed the electrical plates, in one face of which the final branches of the nerves that supply the organ are distributed. The face on which the nerves ramify, when the discharge takes place, is always negative to the other. This surface is inferior in the Electric Rays (Torpedo), and the shock passes from below upwards; it is anterior in the Electric Cat-Fish (Malapterurus), and posterior in the Electric Eel (Gymnotus), and in the former fish the shock passes from the head towards the tail, and in the latter in a contrary direction. These organs may be traced in an ascending series from those in the Common Rays and in the Nilotic genera Mormyrus and Gymnarchus (where they are without electrical functions, but evidently representing a transitional condition from muscular substance to electrical activity), through the Electric Cat-Fish and the Electric Rays to their highest development in the Electric Eel, a shock from which is said to stun a man. But in all cases the force of a shock depends upon the state of the organ, and if any electrical fish be stimulated to give a succession of shocks these will diminish in intensity till the organ becomes quite exhausted, and will not respond to the stimulus of the nerves. [Gymnotus, Malapterurus, Torpedo.]