Electrical attack and defense - Fishes

Electrical attack and defense

Although most electric fishes generate only mild electric fields for communication and sensory purposes, others can generate currents strong enough to stun prey or ward off predators. The electric organs of an electric ray Torpedo(Torpedinidae) have about 45 columns of electrocytes (700 per column). The columns are oriented dorsoventrally and the current is released dorsally because the dorsal surface of the organ and the overlying skin have lower resistance than the surrounding tissues. Torpedo can generate a discharge of 20–50 volts and several amps in sea water (Feng 1991),and stun prey 15 cm away (see  Subclass Elasmobranchii).The Electric Eel Electrophorus (Electrophoridae),not a true eel but a close relative of the South American knife fishes, can generate pulses of 400 volts, or 1 amp (see Feng 1991) with its several electric organs, the largest of which consists of about 1000 electrocytes. These organs are embedded in the fish’s lateral musculature. The two electric organs of the electric catfishes (Malapteruridae) are located on either side of the body and each contains several millionelectrocytes. These organs generate a current of about 300 volts. Other fishes that emit strong electric currents includethe stargazers (Astroscopus, Uranoscopidae), in which electroplaquesare derived from ocular muscles.