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Electric Organ Discharge Displays during Social Encounter in the Weakly Electric Fish Brienomyrus niger L. (Mormyridae)
Author(s) -
Moller Peter,
Serrier Jacques,
Bowling Deborah
Publication year - 1989
Publication title -
ethology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.739
H-Index - 74
eISSN - 1439-0310
pISSN - 0179-1613
DOI - 10.1111/j.1439-0310.1989.tb00498.x
Subject(s) - electric fish , electroreception , electric organ , fish <actinopterygii> , biology , range (aeronautics) , zoology , ecology , fishery , materials science , biochemistry , torpedo , acetylcholine receptor , receptor , composite material
We investigated the electric organ discharge (EOD) activity of the mormyrid fish Brienomyrus niger during social encounters. The fish were contained in porous ceramic shelters and tested alone and in pairs in an experimental tank designed to restrict communication to the electrosensory modality. We moved one fish toward and away from a stationary conspecific, beginning at a distance known to be outside the range of communication (250 cm). Baseline EOD activity was recorded prior to interaction and categorized as ‘variable’, ‘regular’, and ‘scallop’. When moved closer together, the fish modulated this baseline activity in four ways: (1) At 100–130 cm apart, the stationary fish emitted a maximum of sudden EOD rate increases which defined the outer limit of its communication range. (The associated Electric Field Gradient was 1 μV/cm). (2) Long EOD cessations, which we called social silence, lasted from 5–130 s and occurred most frequently when the fish were 36 to 55 cm apart (EFG: 100 μV/cm). The duration of social silence was negatively correlated (r = − 0.862) with the responding fish's size, and was independent of the partner's sex and size. Fish whose EOD baseline pattern was ‘scallop’ were least likely to fall electrically silent, and those that were categorized as ‘regular’ or ‘variable’ were most likely to cease discharging. (3) Within electrolocation range, fish ‘regularized’ their EOD activity while the partner was ‘silent’ (EFG: 1 mV/cm). (4) Following long EOD cessations the fish resumed discharging with characteristic EOD rebound patterns. The possible ethological significance of these findings is discussed.