Springhares Are The Latest Mammals To Have Their Glow-In-The-Dark Secret Powers Revealed

Springhares, large and unusual rodents, just got more unusual. Image courtesy of J. Martin and E. Olson, Northland College; from Olson et al. 2021, Scientific Reports

The ever-growing gang of glow-in-the-dark biofluorescent mammals has got a new member: the springhare, a large and unusual rodent that hops around parts of Africa in the dead of night.

As reported in the journal Scientific Reports this week, scientists have shown how springhares glow with “vivid biofluorescence” when hit with ultraviolet light. This ability is thanks to their fur, which can absorb ultraviolet light and re-emit it as a visible color, rich in hues of pink, red, and orange. 

The radiant fur was spotted in live specimens of two different Pedetes species: the springhare (Pedetes capensis) that lives in southern Africa; and the East African springhare (P. surdaster) that lives in parts of Kenya and Tanzania. Both species are small kangaroo-like creatures that typically lead a nocturnal lifestyle. Despite their name, they’re not closely related to hares, with their branch on the family tree being more closely linked to mice, rats, and other rodents. 

The study authors believe this is the first documented case of biofluorescence in an Old World placental mammal. Plenty of other mammals have recently been found to glow under ultraviolet light, from New World flying squirrels to monotremes. As if the platypus couldn’t get any stranger, a study released last year showed that these egg-laying mammals have biofluorescent fur, appearing green under UV. This trait has also been documented in flying squirrels (hot pink)bilbies’ ears (blue), possums (green), some Australian bats, wombats (blue), and America's only marsupial, opossums (hot pink)

Though the springhare was unexpected, “Our observations also suggest that biofluorescence may be more broadly distributed throughout Mammalia than previously thought,” the authors conclude.

Springhare
Image courtesy of J. Martin and E. Olson, Northland College; from Olson et al. 2021, Scientific Reports

The fact this trait is surprisingly common in mammals suggests it might hold some evolutionary advantage, although scientists are pretty stumped as to what this could be. Some researchers have noted that it could help some solitary animals recognize each other in mating season, while others speculate it might be used to avoid detection for UV-sighted predators by absorbing wavelengths that would otherwise be brightly reflected. 

Unlike other glowing mammals, the biofluorescence seen in springhares is surprisingly patchy, like they got into a paint fight at a rave. The researchers suspect that this patchiness may indicate that springhares are endowed with biofluorescence as a means of camouflage from predators. 

"We speculate that, if their predators are UV sensitive – the unique patterning we observed could function as a sort of camouflage from predators," Erik R Olson, lead study author and associate professor of Natural Resources at Northland College, told IFLScience in an email.

"However, there is a chance that this trait has no ecological significance what-so-ever," Olson added. "It is purely speculation, and until there are behavioral studies and studies assessing the spectral sensitivity of springhare and their predators it will be hard to confirm."

Alternatively, the study also subtly mentions that biofluorescence may be related to some diseases. For example, biofluorescence has been noticed in the development of porphyrias in squirrels, canefield rats, and humans. 

"We were able to determine that porphyrins were, at least partially, responsible for biofluorescence in springhare. The fact that this biofluorescence is porphyrin-based is an important clue. In humans, overproduction of porphyrins is characteristic of a disease called porphyria. Springhares could be depositing or storing excess porphyrins in their fur that might otherwise cause disease," explained Olson. " If that is true, then springhares could potentially help us better understand the disease porphyria."

Either way, you've been rumbled springhares. Right, who's next? 

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