Many have seen the brilliant shimmer of a hummingbird as it hovers in the sun, or observed the prismatic flash of scaly fish bodies darting through shallow streams. But biologists have never observed natural iridecense in mammals – until now.
Enter the golden mole, a subterranean critter whose dense pelt has “an almost metallic, shiny appearance with subtle hints of colors ranging between species from blue to green,” said Matthew Shawkey, speaking to Discovery News last week.
Shawkey is an associate professor in the Integrated Bioscience Program at the University of Akron, OH, where researchers analyzed the molecular structure of hair samples taken from four golden mole species.
They found that the moles’ hair seemed perfectly contoured to reflect light. Each strand has a “reduced cuticular scale” with a wide, smooth reflective surface. A layer of multiple light and dark scales, similar to the composition of certain iridescent beetles, creates the luminous effect. Shawkey’s team used optical modeling to determine that changes in layer thickness result in color variations in the moles.
As if iridescence alone wasn’t strange enough, there’s another twist to the moles’ unique characteristic. The species is completely blind.
Researchers aren’t sure how the shiny fur plays a functional role in their day-to-day survival. It doesn’t aid in communication and, unlike some species with eye-catching physical traits, the moles aren’t poisonous. If anything, their iridescence might make the moles more attractive to predators.
“Many of the nanostructures producing iridescent colors have non-optical properties like enhanced rigidity (think mother of pearl) or enhanced water repellency (such as seen in Morpho butterflies),” Shawkey explained to Discovery News. “In the former case, the color, like in the moles, clearly has no communication function and is a byproduct.”
The researchers’ findings noted that the moles’ hair structure streamlines the animal’s profile and creates less resistance when the moles burrow through dirt and sand. In other words, the vibrant fur may simply be one of nature’s amazing accidents.
Image Credit: David Reber (Creative Commons Share Alike/Attribution License)