Sense
Magnetoception (or magnetoreception) is the ability to detect the direction one is facing based on the Earth's magnetic field. Directional awareness is most commonly observed in birds, which rely on their magnetic sense to navigate during migration. It has also been observed in insects such as bees. Cattle make use of magnetoception to align themselves in a north-south direction. Magnetotactic bacteria build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field.
Magnetoreception
Furthermore, orientation toward the sea, a behaviour commonly seen in hatchlings of a number of turtle species, may rely, in part, on magnetoreception.  In Loggerhead and Leatherback turtles, breeding takes place on beaches, and, after hatching, offspring crawl rapidly to the sea. Although differences in light density seem to drive this behaviour, magnetic alignment may also play a part. For instance, the natural directional preferences held by these hatchlings (which lead them from beaches to the sea) reverse upon experimental inversion of the magnetic poles, suggesting the Earth’s magnetic field serves as a reference for proper orientation.