Moonlight makes desert geckos glow neon green

A desert gecko from Namibia has shiny markings that glow in the dark that glow neon green in the light of the moon. The mechanism that produces its glow has never been seen before in land animals with a backbone.

Palm Geckos (Pachydactylus rangei) have translucent skin with large yellowish markings: stripes on the sides and dark circles surrounding the eyes. But these marks light up brilliantly when they absorb the bluer light of the moon.

Fluorescence – when light is absorbed and then emitted at a longer wavelength – has been found in other reptiles and amphibians, produced by their bones or by chemical secretions in their skin. However, web-legged geckos generate their light using skin pigment cells filled with guanine crystals. These cells, called iridophores, have previously been linked to the display of colors in geckos and lizards, but this is the first evidence that they also allow geckos to glow in the dark.

Related: The 7 strangest glow-in-the-dark creatures

Palm geckos, which live in the dry riverbeds and dunes of the Namib Desert, are around 10 to 15 centimeters long, according to Animal diversity web (ADW), a wildlife database maintained by the University of Michigan Museum of Zoology. Geckos use their large webbed feet to dig in fine sand, and they’re mostly active at night, according to ADW.

In 2018, the study authors found that chameleons have shiny bones through their skin. The discovery prompted scientists to look for hidden lights in other reptiles and amphibians, said study co-author Mark Scherz, a postdoctoral researcher in the Adaptive Genomics Group at Universität Potsdam in Germany.

David Prötzel, lead author of this study and a doctoral student at the Bavarian State Zoological Collection (ZSM) in Munich, kept the P. rangei geckos at home and had “an incredible surprise” when he screened UV light on his canvas. legged geckos and discovered they glowed neon green, Scherz told Live Science in an email. The researchers then tested 55 specimens of P. rangei from ZSM under UV light, finding evidence of fluorescence in adults of both sexes and in juveniles.

The yellowish stripes on the gecko’s flanks are visible to other geckos, but hidden from predators attacking from above. (Image credit: David Prötzel (ZSM / LMU))

In other fluorescent amphibians, such as the polka dot tree frog (Boana punctuated), the glow comes from a chemical that circulates in his lymphatic system. And reptiles such as chameleons and saddle toads in the Brachycephalic The genus exhibits fluorescent bones throughout areas of the body where their skin is very thin.

“In fact, it turns out that many other species, including geckos, have skin that is transparent enough that the fluorescence of their bones can be seen through it under strong enough UV light,” Scherz said.

But in web-legged geckos, the brilliant neon green glow came from the iridophores. Although iridophores were not previously associated with fluorescence in geckos, they are known to fluoresce in some species of reef fish, according to the study. The palmist gecko is the first known gecko to have two types of iridophores: one that is fluorescent and one that is not.

When viewed from below in UV light, the characteristic paws of the webbed-legged gecko, along with the distinctly distributed fluorescent areas, become visible. (Image credit: David Prötzel (ZSM / LMU))

The glow produced by these cells is brighter than the glow emanating from the bones of chameleons and is among the brightest examples of fluorescence in land animals, the study authors reported. Such bright markings along the lower body and around the eye would be very visible to other geckos, “but would be hidden from predators with higher vantage points, such as owls or jackals,” Scherz said. .

Although scientists are not sure how most animals use their fluorescence, the location and brightness of these markings, as well as their visibility in the arid desert environment of geckos, where there is not much vegetation, suggest that fluorescence plays a role in the social interaction of geckos, according to the study.

“We have observed in captivity that although these animals are largely solitary, they rush towards each other to greet each other after a short period of separation,” Scherz said. “They also lick condensation off each other’s bodies. So there are many reasons that being able to see each other over long distances would be useful for these geckos,” he said.

The results were published online Jan. 11 in the journal Scientific reports.

Originally posted on Live Science.

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