ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. The electric fields of four species of wave type, gymnotid fishes were measured and mapped using a technique that allowed accurate assessment of small electric fields, free of unknown field compression and distortion artifacts. 2. Dipole moment values were calculated for each fish's electric field from measurements made at a sufficient distance (Table 1). A dipole moment is an absolute evaluation of the electric fish's field strength that can be used for quantitative, intraspecific and interspecific comparisons. 3. The electric fish, as a field source, represents a distributed rostral pole and a point-like caudal pole (Fig. 2). Deviations of a fish's electric field from that of a dipole field increase with fish size, decreasing water resistivity, and decreasing distance from the fish. 4. Apteronotid species maintain a constant current electric organ output (dropping less than 5%) in water of resistivity up to 15 kOhm · cm, whereas rhamphichthyid species maintain a constant current output only in water up to 10 kOhm · cm (Fig. 6). Within each family, the larger fish maintained their current output level in higher water resistivities than did smaller fish. 5. Electrocommunication distances for the individual fishes are predicted based upon their measured electric field magnitudes and the known electrosensitivities of these species (Table 2); consequences of the geometry of the fishes' electric fields on object detection and object resolution are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00618178
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