UC Irvine

Researchers have found a wide range of organisms to possess the ability to detect, align, and navigate using magnetic fields. While this biophysical mechanism is unknown in most species, there are two leading theories. The first is ferromagnetism which involves either giving animals a physical torque towards the magnetic field, or a cellular channel that is sensitive to magnetic fields. The second theory involves the use of the radical pair mechanism where a spin-correlated pair of radical electrons reacts to the magnetic field through a combination of the hyperfine and Zeeman interactions. The radical electrons are then able to proceed to a spin-selective reaction that may produce a nervous signal.

Under the premise that many photoreceptors on the retina of an eye contain a radical pair magnetic sensor, a procedure is formed to collect the magnetic signal and use it to align or orient oneself. The model must take into account the various angles associated with the magnetic field and surface of the retina, along with possible rotations that the eye can make. The process of orienting involves a simple control loop, and noise is introduced to test the overall robustness of the system to a wide variety of possible pitfalls. A virtual reality simulation using Google Cardboard was created to show what magnetic vision could look like to a human and to birds.

Many experiments were performed on Drosophila melanogaster under a series of different gradient and uniform magnetic fields in horizontal and vertical conditions in a Hirsh maze. The fruit flies exhibited a naive avoidance of magnetic fields at ten times Earth strength fields and were affected by very low intensity magnetic fields.