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No. 112: Jul-Aug 1997

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Sea turtles: from one end to the other

Leatherback turtles are mysterious in several ways: flexible shell, warmbloodedness, etc. (See SF#76 for more.) Now, we add two more remarkable capabilities to their dossier.

Precision navigation. The oily, flexible shells of leatherbacks have made it difficult for researchers to attach radio transmitters to the animals. Their very deep dives (over 1,000 meters) are also inimical to human instrumentation. But S.J. Morreale's group at Cornell have succeeded in attaching pressure-resistant transmitters to the shells on short tethers. This team was able to track female leatherbacks as they left their nesting beach in Costa Rica and headed southward, past the Galapagos, out into the open South Pacific. Surprisingly, all the leatherbacks plied a very narrow corridor each year of the experiment (1992-1995). In fact, the paths were almost for at least 2,700 kilometers southwest of the Galapagos. Highprecision navigation equipment is required here. Among the leatherbacks' "instruments" are probably sensors that detect the angle of the geomagnetic field, the length of daylight, and the identities of the oceanic currents encountered. There are probably other sensors and, of course, a brain to process all the signals; but virtually nothing is known about them.

(Morreale, Stephen J., et al; "Migration Corridor for Sea Turtles," Nature, 384: 320, 1996. Also: Monastersky, R.; "Do Sea Turtles Stop and Ask for Directions?" Science News, 150:342, 1996.)

Rectal gills. Sea turtles are airbreathers that make long, deep dives. To descend deep for long periods, they have evolved a diving adaptation radically different from that employed by the dolphins, whales, and seals; namely, rectal gills. They breathe air at the front end and water at the rear. Water is pulled in through the rectum and directed to sacs lined with blood vessels. These function like fish gills by extracting oxygen from the seawater. The oxygen-depleted water is them expelled and another "breath" is taken.

(Green, John; ISC Newsletter, 11:10, no. 3, 1991. Actual publication date: 1997. ISC = International Society of Cryptozoology.)

Routes taken by migrating leatherback turtles Routes taken by migrating leatherback turtles in 1992.

From Science Frontiers #112, JUL-AUG 1997. 1997-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

Quotes

  • "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