A sensitive optically detected magnetic compass for animals

Proc Biol Sci. 1996 Mar 22;263(1368):295-8. doi: 10.1098/rspb.1996.0045.


Recent experiments have indicated that at least one important magnetic compass used by many animals for navigation may be located in the eye. Here it is shown that a very sensitive magnetic compass is formed by the incorporation of a small quantity of ferrimagnetic single-domain crystals in a droplet of nematic liquid crystal. Optical detection of the compass output is illustrated by experiment and the predicted properties of a biological compass, based upon these principles, are compared with the known properties of the natural compass. Some experiments that could test the model are described.

MeSH terms

  • Animals
  • Magnetics*
  • Models, Biological*
  • Optics and Photonics*
  • Retina / physiology