When animals have shiny feathers or fur, it's usually for some sort of visual display or communication. But what about fauna that lives underground?
Meet Chrysochloris asiatica, the adorable Cape golden mole of South Africa. This species and the other golden moles are named for the characteristic iridescence of their fur. But why do these blind and subterranean creatures need a feature that's almost always visual?
By analyzing the fur of a number of these species, the researchers found it to be incredibly fine, flat and smooth. With multiple layers of the hair packed densely, the iridescence is formed by thin-film interference, which is incredibly sensitive to changes in layer thickness. When the fur moves, tiny changes causes the reflective color to alter, creating multiple hues of reflection.
While undeniably interesting to look at, the shininess probably isn't of aesthetic use to the completely blind mole. More likely, this luster is the unintended result of a more useful adaptation. With their compact bodies, covered ears, and protected nostrils, the golden moles are hyper-adapted for burrowing. They're incredibly streamlined, and their eyes have been completely lost in favor of other sensory organs. Their dense, fine, reflective fur is most likely an adaptation that allows them to slide past soil faster and clean off dirt and sand easily.