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A new study has found, for the first time ever, that there are some bats in the United States that glow in the dark when exposed to ultraviolet light. Now, the researchers are trying to figure out why.
“It may not seem like this has a whole lot of consequence, but we’re trying to understand why these animals glow,” said Steven Castleberry, co-author of the study and a professor in wildlife ecology and management at the University of Georgia Warnell School of Forestry and Natural Resources. “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 the bats?”
The six species of bats – big brown bats (Eptesicus fuscus), southeastern myotis (Myotis austroriparius), gray bats (Myotis grisescens), eastern red bats (Lasiurus borealis), Seminole bats (Lasiurus seminolus), and Brazilian free-tailed bats (Tadarida brasiliensis) – are the first-known bat species in the U.S. to possess this trait.
“Bats have very unique social ecology and sensory systems, and the characteristics we found in these species differs from many other observations in nocturnal mammals,” said Briana Roberson, lead author of the study. “It’s possible for glowing functions to be more diverse than we previously thought.”
Using a light measurement tool, the researchers determined the glow that these creatures emit is a shade of green. The scientists also learned that the glow color was the same regardless of sex or species. They believe it is a genetic characteristic, perhaps an inherited trait used for communication, not something related to the environment in which the animals live.
“It’s ultimately some sort of mutation, and then that mutation somehow gets perpetuated usually because it’s beneficial. Individuals that have that trait tend to survive and reproduce better, so it gets more common in the population. There is evidence that glowing is a common trait,” Castleberry said.
“The data suggests that all these species of bats got it from a common ancestor. They didn’t come about this independently. It may be an artifact now, since maybe glowing served a function somewhere in the evolutionary past, and it doesn’t anymore.”