Interactions of light and gravity reception with magnetic fields in Xenopus laevis.

Tadpoles of Xenopus laevis are shown to respond to magnetic fields using a gravity-related test paradigm. They exhibit a directional selectivity with respect to angular variations of the inclination of low-intensity magnetic fields. This response is abolished when the optic nerves of the tadpole are transected, indicating that the peripheral optical system is involved in the detection of magnetic fields.