In the scientific world right now, it's mammals' time to shine — literally.
Researchers are building a growing (and glowing) list of fluorescent mammals, and a new addition, an endearing jumping rodent called the springhare, just leaped into the spotlight, its brown fur lighting up in swirling disco patterns of pink and orange under ultraviolet (UV) rays.
Scientists recently detected springhares' rosy glow in museum specimens and in live animals in captivity. They found springhares' striking fluorescent colors to be "funky and vivid," forming patterns that were highly diverse "relative to biofluorescence found in other mammals," they wrote in a new study.
Biofluorescent animals have fur or skin that absorbs and reemits short-wavelength light as a longer wavelength, changing its color. Many types of invertebrates, reptiles, amphibians, fish and birds are fluorescent, but in recent years, scientists have also discovered fluorescence in mammals that are active at dusk or nighttime, such as flying squirrels, opossums and platypuses.
Springhares, the sole members of the rodent genus Pedetidae, are also nocturnal. There are two species — P. capensis and P. surdaster — found respectively in southern Africa, and in parts of Kenya and Tanzania. They have short forelimbs and powerful, kangaroolike hind limbs for hopping. And both species glow, according to the study.
Researchers exposed springhares' hidden shine while searching for signs of biofluorescence in flying squirrels and other gliding mammals in the collection of the Field Museum in Chicago, said lead study author Erik R. Olson, an associate professor of natural resources at Northland College in Ashland, Wisconsin. Their quest led them to scaly-tailed squirrels, which didn't glow, and then to a nearby drawer holding the squirrels' closest living relatives: springhares.
"We saw this pinkish-orange biofluorescence in the drawers, and that was an exciting moment," Olson told Live Science in an email. "Seeing something like this, probably for the first time — it really stoked the fires of curiosity."
In all, they examined 14 museum specimens and six captive-bred springhares — five living and one deceased. Under UV light, dark brown fur on the springhares' backs lit up in streaks, spots and patches of vivid pink.
"Both male and female specimens fluoresced in the same regions and with the same intensity," the study authors reported.
Springhares' glowing colors are produced by organic compounds called porphyrins, according to the study. Springhares likely get their pink glow from coproporphyrin and uroporphyrin, which the scientists isolated from the animals' fur, said study co-author Michaela Carlson, an assistant professor of chemistry at Northland College. These two compounds fluoresce in the yellow, orange or red regions of the visible spectrum "depending on the conditions," Carlson told Live Science in an email.
And unlike other glowing mammals, the springhares' bright patterns were highly variable between individuals, and even downright patchy in some.
"The most intensely fluorescent regions were generally around the hindquarters," Carlson said. At first, the scientists wondered if the springhares applied color-changing porphyrins to their fur through grooming, "since porphyrins can be excreted via urine and feces," Carlson said in the email. The researchers ultimately ruled out that hypothesis, since they couldn't wash porphyrins off the springhares' fur. Visible light degrades these chemicals, "so potentially some of the patterning is due to this exposure," Carlson explained.
Another possibility is that the patterning may serve as a type of camouflage, creating visual "noise" that could protect springhares from predators that are UV-sensitive, Olson said.
"However, there is also a good chance this trait doesn't play any role in intra- or inter- species interactions," he added. "Further research is required."
Most — but not all — of the known mammals that demonstrate biofluorescence are most active in low-light environments, which suggests that biofluorescence could be a more widespread feature among species that are out and about during dusk or at night. "But a thorough evaluation of a wider suite of species is still required to determine whether it is in fact more common in this group or not," Olson said.
The findings were published online Feb. 18 in the journal Scientific Reports.
Originally published on Live Science.