Abstract

MACADAR, Omar  and  SILVA, Ana. Electric communication in South American gymnotiform fishes. Rev. Latinoam. Psicol. [online]. 2007, vol.39, n.1, pp. 31-45. ISSN 0120-0534.

We present a description of the electrogenic system and the reproductive behavior of Gymnotiform electrical fishes focusing on sexual and seasonal variations of their electric displays, and the communicative value of their social electric signals produced during courtship, using histological techniques and electrophysiological recordings. The pacemaker nucleus organizes the discharge sequence whereas the rest of the system determines the electric organ discharge waveform, which is species specific. During mating, Gymnotiform fishes show electric discharge sexual dimorphism, and generate transient social signals during courtship and gametoposition. Males of Brachyhypopomus pinnicaudatus prolong duration of the late phase of the discharge and generate brief signals characterized by rate increase and amplitude decrease called "Chirps". Females transiently stop their discharge. These courtship transient signals are always produced over a specially large nocturnal rate increase. Chirps and interruptions are repeated in bursts with a temporal association that suggests communication.

Keywords : Electric organ; Gymnotiformes; Brachyhypopomus pinnicaudatus; Courship; Sexual dimorphism.

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