Earth's magnetic field gets more intense toward the poles, which can help animals orient themselves. Figuring out where the magnetic receptor is, and how it works, still eludes researchers. Iron-based receptors allow animals to figure out how far north or south they are from a location, essentially giving them the latitude. This directional sense probably comes from tiny iron particles called magnetite that float in receptor cells and bump against the sides. By detecting the magnetite particle's movement, the receptor detects the magnetic field's strength, which grows stronger toward the poles.
Receptors activated by light provide different information about the magnetic field.
They act more like a simple compass, indicating which way is north. Having both systems, one for direction and one for position, increases the navigational skills of the animal. You would know where you were. Some animals such as newts and bobolinks probably have both types of receptors. Newts escape predators using the light-activated system that directs them to the beach but use both receptors to find their home ponds.