Magnetism

Whales and Dolphins Trapped Magnetically
No. 38, March/April 1985

Joseph L. Kirschvink, of the California Institute of Technology, has plotted the hundreds of beachings of whales and dolphins along the U.S. east coast. He finds that these cetaceans tend to run aground at spots where the earth's magnetic field is diminished by the local magnetic fields of rocks. These coastal magnetic lows are at the ends of long, continuous channels of magnetic minima that run for great distances along the ocean floors. Kirschvink believes that the stranded whales and dolphins were using these magnetic troughs for navigation and failed to see the stop sign at the beaches and ran aground. The magnetic troughs in this view are superhighways for animals equipped with a magnetic sense.

If Kirschvink's theory is correct, the magnetic sensors of the whales and dolphins are extremely sensitive, because the deepest magnetic troughs are only about 4% weaker than the background magnetic field. Magnetite crystals have been found in birds, fish, and insects, where they are thought to contribute to a magnetic sense of some sort. So far, no magnetite has shown up in whales and dolphins.

(Weisburd, S.; Whales and Dolphins Use Magnetic 'Roads,' Science News, 126:389, 1984.)