A gecko that glows in the dark? This is what a team of researchers from the University of Munich, the Bavarian State Collection of Zoology and the Hochschule München have discovered: a new fluorescence mechanism in a terrestrial vertebrate. The funny thing is that the “machinery” that produces its glow has never before been seen in land animals with backbones.
We know biofluorescence well thanks to many aquatic organisms. Yes indeed; So far, two mechanisms of reptile and amphibian fluorescence have been described: bone-based fluorescence (all bones are naturally fluorescent under ultraviolet light) and fluorescence from a secreted chemical that runs in the lymphatic fluid. Now, we have to add a new fluorescence mechanism in a terrestrial vertebrate.
The Namib cloth-legged gecko, or Namib sand gecko ( Pachydactylus rangei ) is an animal that lives in the dry river beds and dunes of the Namib desert. It is about 10-15 centimeters long and uses its large webbed feet to burrow into the fine sand of the desert. They are usually more nocturnal than diurnal animals. It has translucent skin with large yellowish markings on the sides and rings around the eyes. What we didn’t know until now is that all those marks light up incredibly when they absorb the bluest light from the Moon.
“As soon as we saw this fluorescence, we realized that the cloth-legged geckos must use a new mechanism: the bright neon green fluorescence patterns were clearly produced in the skin of the lizards,” explains David Prötzel, co-author of the work. published in the journal Nature .
Histological study
Histological study of the Namib sand gecko revealed, upon illumination with ultraviolet light, that the fluorescent areas of the skin were filled with special pigment cells, the iridophores, which are absent in the non-fluorescent areas of the skin, making them glow in color. neon green. The scientists tested 55 samples of P. rangei under ultraviolet light, finding evidence of fluorescence in adults of both sexes and also in young creatures.
Iridophores reflect light and play an important role in the coloration of geckos and other lizards. But, for the first time, this study revealed that some iridophores can also fluoresce.
“This effect is much stronger than the bone-based fluorescence we discovered in chameleons three years ago and one of the brightest known cases of fluorescence ever found in terrestrial vertebrates,” comments Frank Glaw, curator of Reptiles and Amphibians at the Collection. Bavarian State Zoology.
The Namib sand gecko is the first known gecko to possess two types of iridophores: one that fluoresces and one that does not.
While scientists do not know how most animals use their fluorescence, the location and brightness of these markings in geckos, as well as their visibility in the arid desert environment, suggests that this fluorescence plays a key role in la social interaction of geckos, according to the study. Seeing another partner from a long distance can be useful.
Referencia: Prötzel, D., Heß, M., Schwager, M. et al. Neon-green fluorescence in the desert gecko Pachydactylus rangei caused by iridophores. Sci Rep 11, 297 (2021). https://doi.org/10.1038/s41598-020-79706-z
