In an exciting discovery in Africa researchers have found that Namibia’s geckos can glow in the dark! Web-footed geckos are native to the deserts of Namibia and have a brilliant neon green glow under the moonlight.
These geckos have translucent skin with large yellowish stripe-like markings on their sides and rings around their eyes. And these strange spots light up brilliantly on absorbing the moon’s bluer light.
Biofluorescence has been observed in reptiles and amphibians prior as well but so far only 2 mechanisms have been described - one is bone-based fluorescence and the other is caused by a chemical that is secreted and circulated in the lymph fluid. However, light in web-footed geckos is produced by groups of granules present in the fluorescent areas of the skin.
These granules are guanine crystals which sit within pigment cells called iridophores. Iridophores are generally whitish or yellowish and are used by many animals for skin colouration. What’s astonishing is that there are 2 layers of iridophores in these geckos, unlike most reptiles which have only a single layer. But out of these 2 layers only the upper one fluoresces while the lower one doesn't. Why so? It’s still not clear.
The glow produced by these cells is brighter than the fluorescence emitted by the chameleon’s bones. Researchers say that the brightness would be visible to other geckos but would be hidden from their predators at higher vantage points. So the markings on their skins could play a vital role in their social interaction.