Nocturnal orientation and object recognition through active electrolocation in weakly electric fish
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Universität Bonn, Institut für Zoologie, Germany
Weakly electric fish orient at night by employing active electrolocation. The African mormyridae emit brief electric pulse-type signals and perceive the consequences of these emissions with more than 2500 epidermal electroreceptor organs, which are distributed over almost their entire skin surface. Electroreceptors project to three somatotopic maps in the lateral line lobe in the brainstem, where primary processing of electrosensory information takes place. Fish can detect and recognize nearby objects by analyzing the electric images, which objects project onto the animal's skin surface. Electric images depend on size, distance, shape, and material of objects and on the morphology of the electric organ and the fish’s body. Behavioural experiments have shown that the mormyrid Gnathonemus petersii can determine the resistive and capacitive components of an object's complex impedance in order to identify living prey items during foraging. In addition, fish can measure the distance and three-dimensional shape of objects. In order to perceive object properties during active electrolocation, the fish have to measure at least four parameters of the local signal within an object's electric image: peak amplitude, maximal slope, image width, and waveform distortions. Fish have certain behavioural strategies in order to optimize object recognition. It is proposed that G. petersii possesses two electroreceptive "foveae" at its elongated chin (Schnauzenorgan) and at its nasal region, both of which resemble the visual fovea in the retina of the eye in design, function and behavioural use.
Conference:
3rd Mediterranean Conference of Neuroscience , Alexandria, Egypt, 13 Dec - 16 Dec, 2009.
Presentation Type:
Oral Presentation
Topic:
Symposium 20 – Mormyrid fishes in myth, membranes and molecules
Citation:
Emde
GV
(2009). Nocturnal orientation and object recognition through active electrolocation in weakly electric fish.
Front. Neurosci.
Conference Abstract:
3rd Mediterranean Conference of Neuroscience .
doi: 10.3389/conf.neuro.01.2009.16.069
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Received:
20 Nov 2009;
Published Online:
20 Nov 2009.
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Correspondence:
Gerhard V Emde, Universität Bonn, Institut für Zoologie, Bonn, Germany, vonderemde@uni-bonn.de