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No. 20: Mar-Apr 1982

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Puzzling Group Behavior Of Sharks

For some unknown reason, sharks often congregate in immense groups. Approximately 2,000 sharks took over 24 kilometers of the surf zone near Corpus Christi during June 1977. Some courageous divers decided to study large groups of the scalloped hammerhead that regularly gather in the Gulf of California. Happily, the hammerheads were not aggressive when so occupied and could be approached closely. They swam pointed in roughly the same direction, maintaining about the same spacing through the groups, which sometimes numbered 100 or more. They did not feed, mate, or do anything collectively; but once in a while an individual would suddenly engage briefly in acrobatic behavior -- one common type was dubbed the "shimmy dance." The researchers concluded that these shark groups had no obvious purpose and that, for reasons beyond the ken of man, this behavior somehow contributed to their evolutionary success.

(Klimley, A. Peter; "Grouping Behavior in the Scalloped Hammerhead," Oceanus, 24:65, Winter 1981/1982.)

Comment. The sharks might be much "farther along" without complex, time-wasting group behavior. What do sharks know about evolution anyway?

From Science Frontiers #20, MAR-APR 1982. 1982-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "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

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..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