Animal magnetism

Turtles may use Earth's magnetic field when migrating

source: New Scientist vol 211 no 2826, August 20 2011 starts p34, 2 pages long

Loggerhead turtles may use the Earth's geomagnetic field when they are migrating. Young loggerheads appear to hatch with directions that ensure their first migration is always in warm water. They gradually develop a recognition of magnetic field lines, but it is not yet understood how the turtles can sense magnetism. Magnetic receptors, using magnetite crystals, may exist in the turtles' heads. Rainbow trout and salmon also appear to use the earth's magnetic field for migration, and may have magnetite in their noses. They may also use chemical detection of the magnetic field, through eye photopigments.