A paper in the May 13 issue of Nature, "Resonance effects indicate a radical-pair mechanism for avian magnetic compass," reports evidence that the earth's magnetic field is sensed by light-absorbing molecules in the retina of a bird's' eye.
Thorsten Ritz, a postdoctoral associate in the Phillips' lab at Virginia Tech who is now a faculty member in the Department of Physics and Astronomy at the University of California, Irvine, co-authored the paper with Peter Thalau of the Zoologisches Institut, Fachbereich Biologie und Informatik, at J.W. Goethe University, Siesmayerstrasse, John Phillips of Virginia Tech, and Roswitha Wiltschko and Wolfgang Wiltschko, also of J.W. Goethe University.
Any effect of the earth's magnetic field on a photoreceptor's response to light is expected to be extraordinarily weak -- so weak in fact that the possibility of such effects have been largely ignored. But animals have developed specialized visual systems. "Some animals can see ultraviolet light. Some animals can see polarized light," Phillips said.
How animals' nervous systems become adapted to detect different things is the subject of Phillips' research. "As a biologist interested in specialized sensory systems, the question of whether photoreceptors have become specialized for detection of the earths' magnetic field is a fascinating topic," he said.
Asking the question: "Are magnetic sensing and light sensing related?" Phillip's lab has conducted research that has demon
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