“Fluorescence was most common and most intense among nocturnal species and those with terrestrial, arboreal and fossorial habits, with more of their body being more fluorescent,” the study authors said.
“It remains unclear if fluorescence has any specific biological role for mammals. It appears to be a ubiquitous property of unpigmented fur and skin, but may function to make these areas appear brighter, therefore enhance visual signalling, especially for nocturnal species.”
There are various forms of fluorescence, but all involve the absorption of light and a low-level emission, which often resembles a glow.
Role in nature ‘unknown’
The role of this phenomenon in nature remains unknown, but is likely to help animals of the same species communicate.
People and rabbits were the first mammals shown to have fluorescent properties when an academic paper in 1911 found human hair could emit light in the UV range.
Over the years, a smattering of studies have identified specific individual species with fluorescent capabilities and provided unproven anecdotal evidence.
Kenny Travouillon, the acting curator of ornithology at Western Australian Museum, decided to test frozen and preserved mammal specimens from the collection to see how common the trait was.
Frozen and preserved mammal specimens were taken to Curtin University in Perth for analysis under a range of lights at different wavelengths.
Photographs and analysis revealed 125 species, 54 nocturnal and 71 diurnal, glowed under some form of UV light.
Yellow, white and light brown fur was commonly fluorescent, and accounted for 107 species; 47 species had fluorescent bare skin, especially around the mouth and feet; and 68 had glowing claws.
The most fluorescent mammals were typically white or pale yellow, such as the polar bear, southern marsupial mole and an albino wallaby.
One dolphin, the dwarf spinner, was fluorescent, but only its teeth were seen to glow.
White fur, unsurprisingly, was the most common source of mammalian fluorescence, while blue, pink and orange was seen less commonly than expected.
“We report fluorescence for 125 mammal species, from half of all mammalian families and representing almost all clades in the mammalian phylogeny,” the scientists wrote.
“The only major mammalian clade missing from our dataset is the lemurs… [and] we predict this clade will also contain fluorescent species.
“While the amount and location of fluorescence varied between species, all exhibited some form of apparent fluorescence. Areas of fluorescence included white and light fur, quills, whiskers, claws, teeth and some naked skin.”
The research was published in the journal Royal Society Open Science.