The glowing secret of mammals

This composite shows a platypus under visible light (left) and under ultraviolet light and yellow-filtered UV light. The discovery of the platypus’ day glow party trick helped inspire the search for more fluorescent mammals. — ©2023 The New York Times Company

AT first, it seemed to be another caprice of two already unusual animals: Flying squirrels and platypuses were found to be fluorescent, absorbing invisible ultraviolet light and re-emitting it in shocking pink or bright cyan.

But they are far from alone. According to a paper published in the journal Royal Society Open Science this month, lions, polar bears, scaly-tailed possums and American pikas also fluoresce. So does every mammal species a group of scientists could get their hands on.