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A behavioral perspective on the biophysics of the light-dependent magnetic compass: a link between directional and spatial perception?

  • John B. Phillips
  • Rachel Muheim
  • Paulo E. Jorge
Publishing year: 2010
Language: English
Pages: 3247-3255
Publication/Series: Journal of Experimental Biology
Volume: 213
Issue: 19
Document type: Journal article (letter)
Publisher: The Company of Biologists Ltd

Abstract english

In terrestrial organisms, sensitivity to the Earth's magnetic field is mediated by at least two different magnetoreception mechanisms, one involving biogenic ferromagnetic crystals (magnetite/maghemite) and the second involving a photo-induced biochemical reaction that forms long-lasting, spin-coordinated, radical pair intermediates. In some vertebrate groups (amphibians and birds), both mechanisms are present; a light-dependent mechanism provides a directional sense or 'compass', and a non-light-dependent mechanism underlies a geographical-position sense or 'map'. Evidence that both magnetite-and radical pair-based mechanisms are present in the same organisms raises a number of interesting questions. Why has natural selection produced magnetic sensors utilizing two distinct biophysical mechanisms? And, in particular, why has natural selection produced a compass mechanism based on a light-dependent radical pair mechanism (RPM) when a magnetite-based receptor is well suited to perform this function? Answers to these questions depend, to a large degree, on how the properties of the RPM, viewed from a neuroethological rather than a biophysical perspective, differ from those of a magnetite-based magnetic compass. The RPM is expected to produce a light-dependent, 3-D pattern of response that is axially symmetrical and, in some groups of animals, may be perceived as a pattern of light intensity and/or color superimposed on the visual surroundings. We suggest that the light-dependent magnetic compass may serve not only as a source of directional information but also provide a spherical coordinate system that helps to interface metrics of distance, direction and spatial position.


  • Zoology
  • place cells
  • subicular
  • spatial cognition
  • magnetic compass
  • radical pair mechanism


  • ISSN: 1477-9145
Rachel Muheim
E-mail: rachel [dot] muheim [at] biol [dot] lu [dot] se


Functional zoology

+46 46 222 31 93



Centre for Animal Movement Research
Evolutionary Ecology, Department of Biology
Ecology building S-223 62 Lund Sweden