Animals as diverse as migrating geese, sea turtles and wolves are known to navigate using the Earth’s magnetic field. But until now, no one has pinpointed quite how they do it. The sensor, found in worms called C. elegans, is a microscopic structure at the end of a neuron that other animals probably share, given similarities in brain structure across species.
The researchers discovered that hungry worms in gelatin-filled tubes tend to move down, a strategy they might use when searching for food. When the researchers brought worms into the lab from other parts of the world, the worms didn’t all move down but rather they moved at a precise angle to the magnetic field that would have corresponded to down if they had been back home.
The researchers discovered the worms’ magnetosensory abilities by altering the magnetic field around them with a special magnetic coil system and then observing changes in behavior. They also showed that worms which were genetically engineered to have a broken AFD neuron did not orient themselves up and down as do normal worms.