These Bats Glow Green Under UV Light, But the Reason Is Still a Mystery
Squirrels, platypuses, and gophers are all furry mammals that are most active at dawn, dusk, or in the dark. A series of surprising studies have shown that these animals share another, less obvious trait: They all glow when exposed to ultraviolet (UV) light.
University of Georgia researchers added six species of North American bats to the list of strangely luminous mammals in a study published in Ecology and evolution.
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Understanding bat glow
The researchers, led by Steven Castleberry, an ecologist at the University of Georgia, studied the bats among the displays at the Georgia Museum of Natural History rather than in the dense thickets of the forest.
The 60 bat bodies in the museum archives included specimens of big brown bats, eastern red bats, seminole bats, southeastern bats, gray bats and Brazilian free-tailed bats.
All 60 specimens shared a distinctive green glow, which radiated from the specimens’ hind limbs, wings, and uropatagia (the membrane extending between the hind limbs and tail).
The glow was present on both male and female bats, regardless of how long the specimens had been in the museum. Now that this strong signal has been identified, the challenge for the team is to understand what it means.
“It’s cool, but we don’t know why it happens. What is the evolutionary or adaptive function? Does it actually serve a function for bats?” Castleberry said in a press release.
Previous analyzes of other bright mammals have reached only functional dead ends. A study that compared the response of rats (which are highly photoluminescent) to real fur models that included or were stripped of their natural shine. Essentially, the rats didn’t seem to notice or care.
Where does the light line come from?
Other bat species have previously been shown to glow under UV light, but the consistent pattern and wavelength emitted by these closely related bat species adds a new twist to the story.
“The data suggests that all of these bat species got it from a common ancestor. They didn’t arise independently,” Castleberry said.
The authors suggest that UV light may play a role in bat communication, but that additional behavioral research in bats will be needed to confirm whether photoluminescence is still important to bats today or whether it is simply a remnant of an ancient evolutionary adaptation.
As the same glow was shared between species and sexes, the authors say it is unlikely to be used for mating or species identification. The authors hope that identifying why bats glow could reveal insights about their behavior that have not been uncovered by previous studies.
“While it is not yet known whether photoluminescence can serve an explicit ecological purpose, additional information about the adaptive benefits it may provide could be useful in better understanding bat behavior and ecology,” Briana Roberson, the study’s lead author, said in a press release.
Learn more: Protecting North America’s Coolest Bat Species
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