A team of scientists from the Faculty of Sciences of the University of Geneva (Switzerland), has discovered one of the most colorful mysteries of nature : the mechanism that regulates the ability of many chameleons to change color in such a complex way. so flashy and so fast. The study has been published in the journal Nature Communications.
These repeats are famous for their ability to change color depending on the circumstances, for their long and fast tongue, and for their surprising and independent eyes, but, until now, it was unknown how they performed this complicated color change. Researchers have found that these color changes occur through the activation of a network of nanocrystals present in a surface layer of dermal cells of these reptiles called iridophores.
There is also another population of iridophores with larger, less ordered crystals that reflect infrared light. The superposition of these two layers and the way they are organized is a first in the evolutionary scientific world, and it is precisely what allows you to quickly change from a perfect camouflage to a wonderful display of colors. The finding was made thanks to microscopy, photometric videography and computer simulation using photonic crystals.
“ We discovered that the animal changes its colors through the active tuning of a network of nanocrystals . When the chameleon is calm, it organizes itself into a dense network and reflects blue wavelengths. On the contrary, when it is excited, its lattice of nanocrystals is loosened, allowing the reflection of other colors, such as yellows or reds ”, clarify Jérémie Teyssier and Suzanne Saenko, co-authors of the study.
And it is that some male chameleons are capable of modifying their colors in just one or two minutes, in striking pigments, to woo a female to face a male in the fight for a female. “ These colors are generated without pigments, through a physical phenomenon of optical interference . They are the result of interactions between certain wavelengths and nanoscopic structures, like small crystals present in the skin of reptiles ”, explains Michel Milinkovitch, leader of the study.
