Scientists identify iridescence in golden moles

A golden mole specimen from the Museum Victoria collection. Source: Museum Victoria.

The bright hairs of these blind moles aren’t used to attract mates.

Golden moles are native to southern Africa and have been named for the iridescent sheen of their fur, which is a rarity among mammals. According to Kevin Rowe, Senior Curator of Mammals at Museum Victoria, their fur produces a rainbow of colours when viewed from different angles, like the surface of a compact disc.

However, they are blind subterranean animals and are believed to have been that way for millions of years. This gave rise to the question: why would a blind creature that lives in the dark need brightly coloured hair?

A team of scientists set out to discover more about the iridescent colours in mammals. Rowe said they became interested in the golden mole’s colouration while working in the mammal collection at the Museum of Vertebrate Zoology in Berkeley, US.

“Some of our colleagues were studying the structural basis of iridescence in bird feathers, he said. “We wanted to know whether the mechanisms generating the iridescence seen in mammal hairs were similar to other animals.”

The study, published in Biology Letters, suggested that the iridescence in golden mole hairs is produced through mechanisms similar to birds and other animals. But the scientists also found that it serves a very different purpose.

Iridescent colours in other animals are believed to have evolved through sexual selection and were involved in mate choice or camouflage. It has been show to play a key role in attracting mates in many species of birds, beetles, butterflies and reptiles.

In the golden mole, however, the colouration itself is not an evolutionary advantage, but a by-product of the smooth, flattened, and layered structure of the hairs. According to Rowe, this structure probably serves to reduce drag and damage when moving through sand and soil.

“The structural characters of golden mole hairs that produce the iridescent sheen are therefore more likely a result of structural adaptations to deal with the harsh conditions of fossorial living.”

The study also challenges the view that iridescent colouration evolved in various species to attract mates. “That iridescent colouration can evolve in golden mole hairs for structural reasons suggests that its origin in other animals may have served a structural function as well,” said Rowe.

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