You might think Halloween decorations when you hear about glowing bats, yet scientists have recently discovered something truly remarkable. When placed ing, six species of the critters were found to emit a green luminescence, marking a groundbreaking discovery in North American wildlife research. It is the first record of the phenomenon in bats native to that part of the world.
This fascinating revelation joins an increasingly crowded list of fluorescent mammals, from the pink-glowing flying squirrels first discovered in 2017 to platypuses and opossums. But scientists still don’t know why some furry animals glow while others do not. The mystery deepens when you consider that these glowing creatures all share one crucial trait: they’re mostly active when the sun goes down.
The Accidental Discovery That Changed Everything
One of the first reports of glowing mammals came in 2019 and inspired Roberson, referring to the groundbreaking flying squirrel discovery that would spark a scientific revolution. In May 2017, a surprising discovery was made in the woods of Bayfield County, Wisconsin, just about a 5-hour drive north of Promega headquarters. Jonathan Martin, Associate Professor of Forestry at Northland College, was exploring the forest with an ultraviolet (UV) light in search of fluorescent lichen or plant life. What he found instead was a bright pink glow coming from a most unexpected source – a flying squirrel.
That (discovery) sort of set the world on fire, as wildlife biologist Steven Castleberry later recalled. Everybody then was walking around with the UV light, seeing what glowed the next time they shone light on it. This single moment of serendipity would inspire researchers worldwide to grab their UV flashlights and start examining museum specimens with fresh eyes, leading directly to the recent bat discoveries.
Six North American Species That Light Up the Night
Six species of North American bats – big brown bats (pictured), eastern red bats, Seminole bats, southeastern myotis, gray bats and Brazilian free-tailed bats – glow green , new research shows. Researchers from the University of Georgia made this discovery by examining museum specimens in a methodical way.
The researchers examined 60 specimens from the Georgia Museum of Natural History under UV lighting and found that their wings and hind limbs give off photoluminescence. With a light measurement tool, the researchers determined the glow was a shade of green. Unlike the pink fluorescence seen in flying squirrels, these bats emit a consistent emerald-like hue that scientists found both surprising and mysterious.
The Science Behind the Glow
Animal tissues in general, including keratin proteins, exhibit a low-level photoluminescence, but some chemical compounds present in fur generate an additional bright photoluminescence. Two classes of luminophore are currently known to cause photoluminescence in mammal fur–tryptophan metabolites, and porphyrin and its derivatives.
Photoluminescence, including phosphorescence and fluorescence, is the reemission of light from matter after excitation by absorption of an external light source. Think of it like a biological light show where molecules absorb invisible UV rays and transform them into visible colors. The green glow in these bat species differs from both patterns typically seen in other mammals, making their fluorescence uniquely puzzling.
Museum Specimens Hold Century-Old Secrets
A bat collected in 1922 and one caught last decade have something unexpected in common: both glow green when exposed to ultraviolet light, producing the same range of wavelengths. This remarkable consistency across time periods suggests that fluorescence isn’t some modern environmental anomaly but rather an intrinsic biological trait.
Using preserved specimens offered advantages beyond their longevity. Researchers could eliminate potential confounding factors like bacteria or fungi that might naturally fluoresce on live animals. The durability of this glowing property in century-old specimens opens fascinating possibilities for historical research into mammalian fluorescence patterns.
Not for Romance or Recognition
The bats all glow at virtually the same hue, with no differences by sex or species. The consistency of color indicates to researchers that this glowing may be an inherited trait used for communication, as opposed to a feature used to camouflage or attract mates.
But when the researchers compared the wavelength of the bat’s glow with the wavelength of chlorophyll, the green pigment involved in photosynthesis, they found that the colors did not match. They then tested whether the bats use the glow to identify differences in fellow bats, such as determining their sex. However, every specimen ended up having the same wavelength. This uniformity rules out typical explanations like mate selection or species recognition.
The Growing List of Glowing Mammals
A 2023 study found that fluorescence isn’t a quirk reserved for just a lucky few mammal families – in that study, it was found in 125 species. So far, the glowing feature has been reported in around 200 species of mammals. With over 6,000 species of mammals on the planet, there are likely many more to identify with this trait.
The first detailed accounts of mammals with glowing fur date to 1911, when researchers described the phenomenon in rabbits and humans. It has previously been shown in a variety of mammals, including flying squirrels and platypuses, suggesting this trait may be far more widespread than anyone previously imagined.
Ancient Inheritance or Modern Mystery
Both the consistency of color and bats’ ability to see in that nanometer range indicated the photoluminescence is an inherited trait for the bats. The data suggests that all these species of bats got it from a common ancestor. They didn’t come about this independently.
Since fluorescence is found widely in mammals, it is most likely that this feature was inherited a long time ago by the ancestors to all modern mammals. It may be an artifact now, since maybe glowing served a function somewhere in the evolutionary past, and it doesn’t anymore. This evolutionary perspective suggests that fluorescence might be an ancient mammalian trait that has persisted across millions of years.
The Function Remains a Puzzle
For nocturnal animals, fluorescence might offer an invisible channel of communication. It would be visible to their UV-sensitive eyes but hidden from most predators. Whether bats use it this way remains to be seen, but as Roberson noted: It’s possible that glowing functions are more diverse than we’ve realized.
While it’s still unknown whether photoluminescence may serve an explicit ecological purpose, additional information on adaptive advantages it may provide could be valuable for further understanding bat behavior and ecology. The function of the glow remains a mystery, but the study authors said they hope the answer is revealed one day, helping them understand how the animals respond and adapt to environmental changes.
Conservation Implications and Future Research
We’re trying to learn more about bats and how they function in their environments and how they contribute to the ecosystem. If we can figure out the function, if there is a function, it can help us to better conserve and manage these species. Understanding fluorescence could provide crucial insights into bat behavior, habitat needs, and ecological roles.
As researchers continue to investigate, one thing is certain: this discovery opens an entirely new window into bat biology. What started as an unexpected flash of light in a laboratory could illuminate unseen aspects of how these animals interact, evolve and perceive their world. Why do they glow? We don’t know. So continuing to do research on this topic is important, as we may eventually be able to know the answer, and this may lead to more questions.
The discovery of fluorescent bats adds another layer to nature’s hidden light show, reminding us how much we still don’t understand about the creatures sharing our world. The underlying mystery, however, remains: Why do these diverse mammals all show some photoluminescence? As scientists continue peering through UV flashlights at museum specimens and wild animals alike, who knows what other glowing secrets might emerge from the darkness?
What do you think could be the evolutionary purpose behind these glowing mammals? Share your thoughts in the comments below.
Hi, I’m Andrew, and I come from India. Experienced content specialist with a passion for writing. My forte includes health and wellness, Travel, Animals, and Nature. A nature nomad, I am obsessed with mountains and love high-altitude trekking. I have been on several Himalayan treks in India including the Everest Base Camp in Nepal, a profound experience.
