Golden moles, mammals forming the family of Chrysochloridae, which taxonomically is distinct from true moles but to which they resemble due to species convergence, are a small, insectivorous family of burrowing mammals native to southern Africa. It was recently discovered that they have a blue green sheen to their coats, which is a rare example of iridescence in mammals.
The golden moles bear a resemblance to the marsupial moles of Australia, so much so that, if the marsupial/placenta divide is ignored, it’s possible that they were once related.
Matthew Shawkey, a biologist at the University of Akron, Ohio, and his colleagues conducted the first detailed study of the iridescent out hairs and non-iridescent downy hairs from four species of golden moles. The study was published recently in the journal Biology Letters.
The iridescent hairs were highly flattened with much smaller scales, which form multiple layers, alternating between light and dark colors, than their counterparts. These hairs produce iridescence by a phenomenon called thin-film interference. The four studied mole species are blind, so it’s very unlikely that this evolved as sexual ornamentation.
Iridescence is widespread among birds and arthropods, but only rarely seen in mammals. It was thought that like other metazoans, the mammalian integument is limited in color. The four examined golden mole species have sheens ranging from purple to green. The study also examined the color, morphology and optical mechanisms in these hairs.
The authors hypothesize that the iridescence of these animals is a by-product of adaptation for durable, low-friction pelts to make burrowing easier.
Reference: “Iridescent colour production in hairs of blind golden moles (Chrysochloridae)” by Holly K. Snyder, Rafael Maia, Liliana D’Alba, Allison J. Shultz, Karen M. C. Rowe, Kevin C. Rowe and Matthew D. Shawkey, 25 January 2012, Biology Letters.