There are gods bats reflect ultraviolet (UV) lightcovering itself with a luminescent green glow. A new study conducted by the team at Warnell School of Forestry and Natural Resources from the University of Georgia (UGA) and published in the journal Ecology and Evolution verified whether, and to what extent, UV fluorescence was present in 6 species of American batsa phenomenon so far little explored in bats, but present in other mammals. From the results of research published in October 2025 and entitled “Glowing Green: A Quantitative Analysis of Photoluminescence in Six North American Bat Species”, it emerged that these mammals reflect UV light with shades that appear invisible to the human eye, but luminescent greens to imaging tools. This trait seems to be a lot ancient but its function is not yet known, thus opening new questions on the ecology and evolutionary history of these bats which, at the moment, remain unanswered.
What are luminescent bats and why do they glow green under UV: the study
A total of were examined 60 adult samples both males and females of different ages, preserved in the museum collections of the Georgia Museum of Natural History, recording and photographing the effect of each individual under UV lamps. By monitoring the light according to some standard conditions, the researchers were able to quantify the photoluminescence induced by it sensors. The results were then compared between individuals of both sexes and between different species. The six species of bats put under the spotlight (literally) are North American and belong to different genres:
- The brown evening (Eptesicus fuscus);
- The eastern red robe (Lasiurus borealis);
- The Seminole Vestry (Lasiurus seminolus);
- The southeastern bat (Myotis austroriparius);
- The gray bat (Myotis grisescens);
- The Mexican free-tailed bat (Tadarida brasiliensis).
Excluding any type of environmental contamination or related to the conservation of the samples, under ultraviolet light all bats showed a clear sign of photoluminescence in the area of wingsof the hind limbs and the area ofuropatagium (the membrane that extends between the tail and hind limbs). The spectral scans (the “images” produced) revealed a constant emission peak between 520 and 552 nm, corresponding to the color that we will call “greenThe following had to be taken into consideration different habitats origin of the species (preferred environment with more or less poor lighting, altitude, latitude, etc.) as well as the state of conservation of the sample.
The researchers hypothesized that the fluorescence may be connected with less lit environments – like caves – and that it can have a communicative role or that it was passed down from a common ancestor as an evolutionary advantage. The data lead to the hypothesis that there was a common ancestor who underwent aancient genetic mutationpassed down in the form of an evolutionary advantage to this day. What advantage this is, however, is yet to be discovered.
Why the study on luminescent bats is important
This study is relevant for several reasons. First of all it brings something new: it provides us new evolutionary data on bats, given that UV fluorescence is well documented in other groups (beetles, fungi, etc.), but it is little studied and known in flying mammals.
It also helps us understand gods potential ecological and behavioral mechanisms of these animals. If some bats are able to reflect UV light, this could affect, for example, intra-specific communication, predation, echolocation or conservation of these species. It also offers the idea of using fluorescence as a new biological indicator: If fluorescence varies between species or environments, it could be used as parameter non-invasive to study not only populations but also the habitats in which they live.
And last but not least, learning the presence of new characters favors conservation of species: knowledge of the micro-habitats and visual characteristics of individual groups helps us to better define conservation and monitoring priorities in the long term.
A nebulous case that needs new light
As in any self-respecting study, the results should not be seen as answers, but rather as new questions to be answered. Among the implications and future lines of research to focus on, the authors suggest verifying whether fluorescence really exists perceived by bats themselves or by their predators/prey and investigate whether this trait has a communicative, protective function (e.g. visual camouflage, keeping predators away) or seasonal and proceed with the analysis of live samples while avoiding or minimizing capture disturbance.
A new development could be expected extend the study to more bat species (beyond the six considered) to evaluate broader phylogenetic ranks, keeping in mind how today’s habitat modifications can affect the visibility of the fluorescence and therefore the ecological dynamics of the species under analysis.
This work opens a fascinating window on the “hidden light” in the world of bats, making us understand that even in bats there can be surprising visual phenomena. The results, the experts quote, “suggest the possibility that photoluminescence has ahomologous origin between species examined.” However, the impossibility (at least at the moment) of demonstrating an ecological function of fluorescence will require new specific analyseswhich will allow us to get closer to a better one comprehension as well as conservation of these animals.
