By Leah Crane
Many amphibians glow under blue light
J Lamb, M Davis/St Cloud State University, Minnesota
Many species of salamander and frog are naturally fluorescent, glowing green under certain wavelengths of light, and we dont yet understand why.
Biofluorescence occurs when light hits a living organism and is absorbed and re-emitted at a different wavelength, like when your white teeth glow blue under UV light. We know that many sea creatures are fluorescent, but there has been relatively little study on amphibians.
Jennifer Lamb and Matthew Davis at St. Cloud State University in Minnesota examined individuals from 32 different species of amphibian, mostly frogs and salamanders, to figure out if they would fluoresce under blue light. Every single species did: most lit up green when exposed to bright blue lights, although a few were a bit more yellow.
Most of the fluorescence seemed to come from pigments in the animals skin, but some also came from mucus excretions or even bones. Its really cool to look at developing amphibians, like tadpoles and baby salamanders, and you can see it in the growing limbs, says Lamb.
It isn’t yet clear exactly what purpose the fluorescence serves, says Lamb. It could help warn off predators, similar to the brightly coloured markings on some animals, or maybe it could help individual amphibians identify one another.
In some species, we do see differences in colour patterns between males and females, so it could be related to reproduction, says Lamb. In the loudness of a frog chorus, with hundreds calling at once, perhaps females could use the light to find a specific male when the audio signals arent helpful. She and Davis are now working on figuring out the exact mechanism behind the fluorescence and its use to the amphibians.
This new-found fluorescence could also help scientists see amphibians in the wild. There are plenty of small frogs and things that can be really hard to spot, but we could use fluorescence to detect them and that could help us in conserving these hard-to-find species, says Lamb.
Journal reference: Scientific Reports, DOI: 10.1038/s41598-020-59528-9
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By Leah Crane