SENSORY SYSTEMS, PERCEPTION, AND LEARNING | Magnetic Sense in Fishes

Abstract

Behavioral experiments have shown that fish can detect both the direction and the intensity of the Earth’s magnetic field, but how they detect the field is still unresolved. Teleost fishes may detect magnetic fields using magnetite, a magnetic mineral that acts like a miniature compass needle, found inside cells within the nose. In contrast, elasmobranch fishes may use either magnetite or the electroreceptor cells in the ampullae of Lorenzini that detect the electric fields induced as the fish, the seawater medium, or both the fish and the medium move through the Earth’s magnetic field. The trigeminal nerve carries magnetic field information to the brain in teleost fishes, whereas the octavolateralis nerve in elasmobranch fishes responds to electric fields induced by either movement through or variations in the external magnetic field. The magnetic sense potentially permits fish to navigate accurately during homing and migration, but whether fish actually navigate using the magnetic sense is still unknown.