The mystery of magnetoreception
Have you ever wondered how certain animals, such as migratory birds and butterflies, are able to sense direction?
Well it turns out that such animals have the ability to navigate using the Earth's magnetic field. Magnetism-sensing animals are able to perceive the change in the inclination of magnetic field lines as they're flying, allowing them to not only orient themselves with regard to north or south, but to gauge their approximate distance between the magnetic equator and the nearest magnetic pole.
Exactly how these animals employ magnetoreception is still a mystery. In 2012, two neuroscientists from Baylor College successfully identified magnetically sensitive neurons in the brains of homing pigeons. Another group of scientists from the University of Illinois at Urbana-Champaign focused on radical pairs (molecules with unpaired electrons that form when electrons start jumping between neighboring molecules ... it's all very much over my head) because the amount of time the unpaired electrons spend in either a parallel or antiparallel spin state is influenced by magnetic fields. The two electron spin states enable different chemical reactions to occur, and scientists hypothesize that fluctuations in the reactions could be detected by sensory neurons.
More recently, scientists have discovered a photoreceptor protein in the retinal tissues of several migratory birds that produces free radicals when exposed to light. Since the discovery, researches have produced enough experimental evidence to suggest that the cyptochrome in question is indeed involved in magnetoreception. But many questions still remain; such as how cyptochrome, radical-pair reactions, retinal neurons, and the animals' behavior is all connected.
For me, this is the most exciting kind of research; puzzles that combine pretty much every scientific field. Neuroscience, physics, chemistry, animal behavior ... no wonder this mystery has proved so difficult to uncover. The secret of magnetoreception may be a discovery destined for the distant future, but scientists continue to make (extremely exciting) progress.
Beth Rogers '16
Read more here: http://www.the-scientist.com/?articles.view/articleNo/36722/title/A-Sense-of-Mystery/
(image sources: theguardian.com, the-scientist.com)