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Electric Fish Not Backward In Data Processing

The incredible sophistication of the brain and nervous system of fish using active electric sensing is evident in the South American fish Eigenmannia. This fish (different from the knife fish above) emits electric pulses at frequencies betwen 250 and 600 per second for electrolocation and communication. M. Kawasaki, at the University of Virginia, has investigated what happens when two of these fish operating on similar frequencies meet. Ordinarily, the fish would jam each other's sensory apparatus and "blind" each other. To circumvent this Eigenmannia has evolved a "jamming avoidance response," in which they both shift their pulse frequencies away from each other. To accomplish this, the fish must be able to detect time disparities between the two sets of signals less than 1 microsecond long. Their individual electroreceptors are not capable of handling such small time differences. Kawasaki has concluded that the jamming avoidance response can come only from highly sophisticated signal processing in the fish's central nervous system.

(Kawasaki, Masashi; "Temporal Hyperacuity in the Gymnotiform Electric Fish Eigenmannia," American Zoologist, 33:86, 1993.)

Comment. Echo-locating bats and dolphins also possess sophisticated data processing apparatus for analyzing the echos they receive back from their prey and surroundings. It will be interesting to discover if evolution has come up with similar organic "components" for handling acoustic and electric signals. Further, we know that some insects have developed ears and sound generators to detect and jam hunting bats. Have the prey of electric fish evolved corresponding countermeasures? If not, why not?

From Science Frontiers #89, SEP-OCT 1993. 1993-2000 William R. Corliss

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  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

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  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987