ELECTROLOCATION OF CAPACITIVE OBJECTS IN 4 SPECIES OF PULSE-TYPE WEAKLY ELECTRIC FISH .1. DISCRIMINATION PERFORMANCE

VONDEREMDE, G and RINGER, T (1992) ELECTROLOCATION OF CAPACITIVE OBJECTS IN 4 SPECIES OF PULSE-TYPE WEAKLY ELECTRIC FISH .1. DISCRIMINATION PERFORMANCE. ETHOLOGY, 91 (4). pp. 326-338. ISSN 0179-1613,

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Abstract

The great variety of species-typical electric signals (electric organ discharges, EOD) emitted by weakly electric mormyrid fish might be the result of evolutionary pressures stemming from the two main functions of the electro-sensory-motor system: electrocommunication and electrolocation. Employing a conditioned discrimination task we tested four species of mormyrids, emitting EODs differing in waveform, for their ability to detect capacitive properties of objects during electrolocation. Each fish could discriminate capacitive objects within a certain range of capacitive values, which was species specific. The upper and lower limits (upper and lower thresholds) of this detectable range were determined for each fish. In fish species emitting long duration EODs composed of mainly low spectral frequencies both the lower and the upper thresholds were shifted to larger capacitive values compared to fish species emitting shorter EODs. The upper limit of the detectable range was much more variable between species than the lower limit, which was relatively low in all fish. We interpret this as an adaptation of mormyrids to detect small capacitive objects, for example food items. All mormyrids could discriminate between a resistive object and a capacitive object even if the complex impedances of the two objects were identical. This implies that the fish are highly sensitive to small waveform distortions of their self produced EODs.

Item Type: Article
Uncontrolled Keywords: ORGAN DISCHARGE EOD; GNATHONEMUS-PETERSII; MORMYRID FISH; COMMUNICATION;
Depositing User: Dr. Gernot Deinzer
Last Modified: 19 Oct 2022 08:44
URI: https://pred.uni-regensburg.de/id/eprint/54439

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