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.
Klaus Schulten
Schulten also began to explore the possibility that fast triplets could explain compass sensors in biological species such as migrating birds. That the European robin used some form of magnetoreception was demonstrated by Wolfgang Wiltschko and Fritz Merkel in 1965, and further studied by Wolfgang and Roswitha Wiltschko. Schulten proposed that quantum entanglement of a radical-pair system could underlie a biochemical compass. Schulten and others have since extended this early work, developing a model of the possible excitation of cryptochrome proteins in photoreceptors within the retina of the eye.