Video recordings of prey capture behaviour and associated electric organ discharge of Torpedo marmorata (Chondrichthyes)

The results of an analysis of 16 laboratory records of Torpedo marmorata Risso attacks are presented: when a fish swims near a T. marmorata at rest, the latter jumps and simultaneously immobilizes the prey by its electric organ discharge (EOD). A water stream is used to direct the paralysed prey beneath its disc before swallowing. The attack is made if the prey swims at short distance ( 4 cm); height and direction of the jump are related to the position of the prey. The EOD, interrupted during the jump, reappears when the prey moves under the disc of T. marmorata, and ceases before swallowing. The strength of the EOD is sufficient to break the vertebral column of the prey. The possible receptor organs involved in this behaviour are presumed to be lateral line organs and touch detectors: the former to localize the prey before the jump, the latter to detect it under the disc. Evolutionary convergence of the prey capture behaviour of Torpedo, Malapterurus, and Electrophorus is also discussed.Supported by Research Grant No. 659440 from the Direction de Recherches et Moyens d'Essais (D.R.M.E.) to Dr. T. Szabo.Dr. Bauer's stay in France was sponsored by a N.A.T.O. and a D.F.G. research fellowship.