Scientists have shown how birds might be able to see the Earth's magnetic field, helping them to navigate. A team from Oxford University and Arizona State University, writing in this week's Nature, have uncovered a chemical trick that could enable some animals to see magnetic fields.
(c) Alan D. Wilson, www.naturespicsonline.com" alt="Female Mallard in flight" />Peter Hore and his colleagues studied a molecule containing three key chemical groups, a carotenoid (C), a porphyrin ring (P) and a fullerene (F); this was chosen to mimic the behaviour of some of the light-sensitive pigments found in the retina. Using this molecule the team found that when they shone light of a certain wavelength at it, the CPF produced a pair of chemicals called free radicals, one at each end of the molecule.
Normally these free-radicals would quickly recombine and cancel each other out, but when the team applied a magnetic field similar in strength to the Earth's magnetic field, a quantum property of the radicals known as their electron "spin" was altered.
"This could trigger a chemical in the eye to change shape, which could in turn kick-start other biochemical processes to enable a bird to see the Earth's magnetic field," says Hore. Birds could use this information as a reference frame to aid their navigation when visual cues aren't available, such as at night, and during flights over the ocean.