According to The Independent, a number of teeny, tiny toads discovered deep in the Brazilian rainforest are very unusual indeed… they actually have fluorescent skeletons, bones that glow in the dark, and the glow might help them communicate with each other.
The new kids on the block are called Pumpkin Toadlets. They use the natural glow of their bodies to signal to their fellow toadlets and also to let predators know they’re poisonous. It was an unexpected discovery, made while examining the way the toadlets interact in the mating season, at a time the team decided to shine a UV light on the animals’ backs to see better. The researchers were astonished to see the toads glowing in the dark.
These toads are not the planet’s only fluorescent creatures, though. As it turns out plenty more animals harness a natural fluorescent glow, and they do it for all sorts of reasons. Some spiders do it, some chameleons do it, even some birds glow in the dark, but humans can’t see the glow without a UV lamp.
These toadlets actually have 100% fluorescent skeletons. The light only shows through the skin where the flesh is thin, in places where there are fewer or no dark pigment cells, which lets the light travel easily through it. The result is a series of strange blue-white patches. Because these toads are active during the day, the theory is the UV in sunlight makes a glow that some animals can see.
In parrots and spiders, a similarly patchy glow seems to play a sexual communication role. And the puffin’s remarkably colourful beak has recently been found to glow under UV light, maybe also playing a role in reproduction. But the toads need to be researched carefully to reveal the actual purpose of their fluorescence.