Magnetic-field perception

摘要

The ability to perceive Earth's magnetic field, which at one time was dismissed as a physical impossibility, is now known to exist in diverse animals. The receptors for the magnetic sense remain elusive. But it seems that at least two underlying mechanisms exist-sometimes in the same organism.rnThe evidence for magnetoreception is mainly behavioural. The most common approach has been to alter the magnetic field around animals and watch for corresponding changes in orientation or navigation behaviour. Usually this has been done in the lab, where carefully calibrated magnetic fields can be produced. But experiments have also been done in the field on unrestrained animals that are migrating or homing.