Scientists have discovered a vivid porphyrin-based biofluorescence in two species of springhares, Pedetes capensis and Pedetes surdaster.
Captive Pedetes capensis photographed under visible light (three insets) and under 395 nm UV light with a 470 nm longpass filter to documenting the orange to red biofluorescence ( 650 nm) of springhare. Images contain two different captive-bred, captive individuals (female — bottom two larger images under ultraviolet light; male — all remaining images) from the Omaha’s Henry Doorly Zoo & Aquarium in Omaha, Nebraska, the United States. Image credit: Olson et al., doi: 10.1038/s41598-021-83588-0.
These creatures are nocturnal, fossorial grazers that inhabit semi-arid areas. They are mainly solitary, sheltering in their own burrows during the day and preferentially foraging individually in short-grass environments at night.
“Biofluorescence, the absorption of short wavelengths of light and re-emission of longer wavelengths of light, has been increasingly observed in a wide range of invertebrates, fishes, reptiles and amphibians, and birds,” said Dr. Erik Olson from the Departments of Environmental Sciences and Natural Resources at Northland College and colleagues.
“We’ve discovered a funky and vivid porphyrin-based biofluorescence in Pedetidate, representing the first well-documented biofluorescence of an Old World eutherian mammal.”
In the study, the researchers examined 14 museum specimens, including eight specimens of Pedetes capensis collected from Angola and Botswana, and six specimens of Pedetes surdaster collected from Kenya and Tanzania.
They also observed and photographed biofluorescence on five living captive-bred individuals of Pedetes capensis at Omaha’s Henry Doorly Zoo and Aquarium in Omaha, Nebraska and one individual at the Mesker Park Zoo & Botanic Garden in Evansville, Indiana, the United States.
All individuals exhibited orange to red biofluorescence, although the scientists did observe variation in the intensity of biofluorescence across individuals.
“We observed fluorescence of individual springhare hair fibers and variation in the presence of fluorescence within individual hair fibers, suggesting that the fluorescence is distributed through the thickness of the cuticle and absent from the core and tips of hair fibers,” they said.
“The fact that biofluorescence was not easily removed via washing and was present on museum specimens from 1905 suggests that the biofluorescence is a part of the physical anatomy of the hair fibers for Pedetidae.”
Biofluorescence appeared more vivid in living individuals of springhares than in museum specimens, potentially indicating some degradation over time.
“The ecological implications of biofluorescence in springhares remain unknown,” the authors said.
“However, like other biofluorescent animals, they are nocturnal.”
“Biofluorescence in mammals has been detected mainly in nocturnal-crepuscular and UV-sensitive species, and UV-color vision appears to be ecologically important to many nocturnal-crepuscular mammals.”
“While we cannot determine why Pedetidae exhibits biofluorescence, our observations add further support for the hypothesis that biofluorescence and UV wavelengths of light may be ecologically important for nocturnal-crepuscular mammals,” they said.
“Our observations also suggest that biofluorescence may be more broadly distributed throughout Mammalia than previously though.”
A paper describing the discovery was published February 18, 2021 in the journal Scientific Reports.
E.R. Olson et al. 2021. Vivid biofluorescence discovered in the nocturnal Springhare (Pedetidae). Sci Rep 11, 4125; doi: 10.1038/s41598-021-83588-0