As soon as Jamie Dunning flipped on the black light in his lab, the Atlantic puffin's beak lit up like a neon Christmas tree.

The University of Nottingham research student was studying the dead animal as part of his work on bird genetics when he remembered something a colleague had told him: Crested auklet feathers glow when viewed under a UV light.

Since puffins are closely related to auklets, Dunning's curiosity was piqued—and sure enough, his specimen's beak glowed orange.

“I was so excited," Dunning says. "It was completely undocumented." (See pictures of other animals that glow.)

Biofluorescent animals reflect the blue light hitting a surface and re-emit it as a different color—the most common being green, red, or orange.