Duck-billed, egg-laying platypuses just got a little weirder: It turns out their fur glows green and blue under ultraviolet (UV) light.
Under visible light a platypus’s extremely dense fur — which insulates and protects them in cold water — is a drab brown, so the trippy glow revealed under UV light on a stuffed museum specimen was a big surprise.
Biofluorescence — absorbing and re-emitting light as a different color — is widespread in fish, amphibians, birds and reptiles. But the trait is much rarer in mammals, and this is the first evidence of biofluorescence in egg-laying mammals, also known as monotremes, scientists reported in a new study.