Just take a glance at any photo of flying squirrels and you will inevitably think they are awesome creatures. But even beyond their cutesy first impressions, these gliding rodents hold an extremely cool trick up their furry little sleeve: hot pink ultraviolet fluorescence.
Researchers have discovered that flying squirrels glow a vibrant shade of bubblegum pink when placed under ultraviolet light – a trait that's almost unheard of among mammals (unless you count gene editing).
The discovery, like all good discoveries, came about by accident.
“My colleague, Jon Martin, a Forestry Professor at Northland College, had an interest in biofluorescence and started wandering around in the woods at night with a UV flashlight, looking for other things that might be worth documenting in the forest canopy: lichens, fungi, plants, and frogs,” Paula Spaeth Anich, study author and Associate Professor of Natural Resources at Northland College, told IFLScience.
“One evening, he heard the chirp of a flying squirrel at a bird feeder, pointed the flashlight at it, and was amazed to see pink fluorescence.”
Stunned by his discovery, Martin reached out to a few of his colleagues who knew about wildlife, but was met with heavy skepticism (and who could blame them?)
“He texted Professor Erik Olson, who was a little bit skeptical,” said Anich. “I have to admit that the discovery was a little confusing to me. I tried to put it into some context I could understand: Was this due to diet? Was this a local phenomenon?”
Reporting in the Journal of Mammalogy, the team found that all threes species of New World flying squirrels, both male and female, display some level of UV fluorescence, although to varying degrees. They applied UV light to over 100 flying squirrels from the Glaucomys genus: the southern flying squirrel, the northern flying squirrel, and Humboldt's flying squirrel. Their findings show that all but one of the Glaucomys individuals’ fur let off a dazzling pink UV fluorescent glow that was hidden to the naked human eye.
This begs the question, what business does the flying squirrel have with pink fluorescence? The researchers aren’t exactly sure, but they suspect its something to do with their nocturnal lifestyle. It’s possible that it is just used so squirrels can find their friends in the pitch black forests or, perhaps, it’s a matter of sexual selection used to impress members of the opposite sex, just like a peacock's plumage or an elk’s antlers.
Alternatively, it might be part of a super-smart anti-predator device used to dazzle and confuse any would-be attackers. The researchers argue that it could even be used as camouflage, strangely enough. Much like the way some tropical fish use fluorescence to camouflage themselves against fluorescent corals, flying squirrels may have adapted to the fluorescing lichen-covered forests of North America by fluorescing themselves.
These little pink parachutes aren't the only creatures that glow under UV light. It was discovered just last year that both puffins beaks and chameleon bones also glow, which was apparently only known to themselves until a scientific human stumbled upon them with a UV light.