Golden moles have a blue-green sheen to their coats that is a rare example of iridescence in mammals, report Matthew Shawkey at the University of Akron in Ohio and his colleagues.

The group conducted the first detailed study of iridescent outer hairs and non-iridescent downy hairs from four species of golden mole. Iridescent hairs were highly flattened with much smaller scales than their less eye-catching counterparts. The scales form multiple layers, which alternate in colour between light and dark, and probably produce colour as light passes between layers in a phenomenon called thin-film interference.

All four mole species are blind, so it is unlikely that the hairs evolved as sexual ornamentation. The authors suggest that the iridescence of these burrowing animals is a by-product of adaptations for durable, low-friction pelts.

Credit: P. MORRIS/ARDEA.COM

Biol. Lett. http://dx.doi.org/10.1098/rsbl.2011.1168 (2012)