They say there’s no place like home for the holidays… but how do you get there? If you’re a bird, turtle, lobster, or even a bacteria, chances are you’ll be relying on the earth’s magnetic field.

Image credit: Marilyn M. via Flickr (CC BY-NC-ND 2.0)

Magnetoreception, the ability to detect magnetic fields, is one of the most mysterious biological superpowers. It’s often described as a kind of built-in compass, but many animals show such delicate sensitivity to fluctuations in Earth’s magnetic field that they’re able to treat it more like a map, directing them to a specific mountain or island year after year.

Scientists aren’t sure exactly where sensory organs associated with magnetoreception might be located, making it difficult to study. So far, there are two proposed theories for how it works: the first relies on tiny magnetite particles in specialized cells (first discovered in bacteria and trout) that align themselves with an applied magnetic field; the other involves cryptochrome, a molecule found in the eyes of many birds that could allow them to “see” magnetic fields.