Iridescent mammals are much more common than we thought

Studies reveal that over a dozen mammal species exhibit shimmering purple and green fur, reminiscent of precious gemstones. This phenomenon, known as iridescence, causes colors to shift based on the viewer’s angle, resembling the visual effect seen on surfaces like oil slicks or the bright plumage of hummingbirds. Surprisingly, this quality is more prevalent among mammals than previously appreciated.

Jessica Leigh Dobson from Ghent University, Belgium, stumbled upon this phenomenon while analyzing mammal specimens at the Royal Museum for Central Africa. Observing an unexpected blue sheen on the fur of the tropical vlei rat (Otomys tropicalis), she was inspired to investigate further.

“I quickly returned to my office to verify whether this had been documented, as all my readings indicated that mammalian iridescence was exclusive to golden moles,” remarked Dobson. The golden mole, a burrowing mammal, is unexpectedly more related to elephants than to true moles, garnering its name from its shiny hairs.

Upon delving into scientific literature, Dobson discovered sporadic references to glittering fur in other mammal species dating back over a century. Working with her team, she meticulously examined specimens associated with anecdotal accounts of iridescence or those related taxonomically. Utilizing light microscopy, they analyzed the reflected wavelengths of light from fur at various angles, identifying a vivid spectrum of color reflections.

The results were unexpected: golden moles are not singular in their shimmering appearance. An additional 14 mammal species exhibit similar iridescent qualities, including a diverse array of rodents and the giant otter shrew (Potamogale velox), a unique predator with aquatic habits. Notably, six of these species had never been scientifically recognized for their iridescence before this research.

“This comprehensive examination sheds light on a previously underexplored and often overlooked phenomenon,” commented Beth Reinke from Northeastern Illinois University, who was not part of the research.

Investigating the hair structure of these iridescent mammals revealed notable characteristics: each hair was remarkably smooth and consisted of a series of tightly compressed sub-parallel layers. These layers bend light differently, resulting in the shimmering colors, as noted by Dobson.

The research team hypothesizes that this sheen may be an evolutionary adaptation related to their living environments. Most of these mammals are either burrowing or aquatic, suggesting that the smoothness of their fur could assist in maintaining cleanliness in muddy or wet habitats.

Nevertheless, the iridescence could also serve a communicative purpose akin to many bird species, Dobson speculates, opening the door to new avenues of exploration in this area.

Looking ahead, there are numerous opportunities for discovery. A new species of shrew recently identified in Indonesia has shown signs of iridescent fur, suggesting that more species await recognition in this fascinating realm. Dobson is enthusiastic about the prospect of uncovering more about this captivating phenomenon, especially considering that there are about 2500 rodent species, and only a small fraction has been studied.

Topics: