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No. 91: Jan-Feb 1994

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Crayfish Communication

It always comes as a surprise when we find supposedly primitive organisms employing our highly technical concepts; for example, the jamming-avoidance techniques of electric fish (SF#89). Still another potential example has been advanced: The lowly crayfish is now thought to enlist some of our sophisticated information theory.

Crayfish often live in noisy environments, where one would expect acoustical information transmission would be degraded. This would be true enough if linear information theory applied, but some, perhaps all, real situations are nonlinear. In such instances, information flow can actually be enhanced by the presence of optimized random noise. Stochastic resonance (SR) is the term applied in such cases of nonlinear statistical dynamics. J.K. Douglass et al write:

"Although SR has recently been demonstrated in several artificial physical systems, it may also occur naturally, and an intriguing possibility is that biological systems have evolved the capability to exploit SR by optimizing endogenous sources of noise. Sensory systems are an obvious place to look for SR, as they excel at detecting weak signals in a noisy environment. Here we demonstrate SR using external noise applied to crayfish mechanoreceptor cells. Our results show that individual neurons can provide a physiological substrate for SR in sensory systems."

Put more simply, the crayfish nervous system has the potential for cashing in on SR in noisy environments. However, the authors also remark that humans, too, accordingly to psychological experiments, seem to harness SR in the perception of ambiguous figures in noisy situations.

(Douglass, John K., et al; "Noise Enhancement of Information Transfer in Crayfish Mechanoreceptors by Stochastic Resonance," Nature, 365:337, 1993.)

Comment. In humans, then, and probably crayfish and other life forms, evolution via random mutation has just happened to hit upon a very sophisticated technique for improving communication!

From Science Frontiers #91, JAN-FEB 1994. 1994-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

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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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  • "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