People have been curious for a long time now about how chameleons change colors and finally the word is out! A recent study shows that by making adjustments in the layer of unique cells that is exists within their skin, they change their colors.
Researchers have found that chameleons do not make modifications in their color tones by procuring or diffusing pigments within their skin cells like squids and octopus do. They actually are reliant on structural alterations which has an effect on how light reflects of off their skin.
The study was conducted by observing 5 adult males, 4 adult female and 4 juvenile panther chameleons (Furcifer pardalis); a type of lizard inhabiting in Madagascar. Chameleons have two masked layers of iridophore cells – iridescent cells which consists pigment and reflect light.
The irodophore cells include nanocrystals of various sizes, shapes and organizations which is the most integral part of chameleons remarkable color shifts. It was found that by either relaxing or exciting their skins chameleons can alter the structural arrangement of their upper cell layer leading to a change in color.
The lead author of the study Michel Milinkovitch, a professor of genetics and evolution at the University of Geneva in Switzerland said “When the skin is in the relaxed state, the nanocrystals in the iridophore cells are very close to each other — hence, the cells specifically reflect short wavelengths, such as blue.”
On the contrary, when the skin is at an exciting state, the distance between adjacent nanocrystals elevates and each iridophore cell which contains these nanocrystals selectively mirrors longer wavelengths like yellow, orange or red. Chameleons are not always blue; their skin also has yellow pigments. When blue incorporates with yellow it makes green, a cryptic color which helps them be camouflaged amongst trees and plants, according to Milinkovitch.
Researchers wrote in the paper that the “red skin hue does not change dramatically during excitation, but its brightness increases.”
In addition to all that, a deeper and thicker layer of skin cells which reflects a great amount of near-infrared sunlight has been discovered by researchers. Even though these cells do not assist in changing colors, but it is likely that they reflect heat off the lizards and helps them to stay cool.
A handful of methods were used to study the iridophore cells, such as filming them with the help of high resolution camera and numerical models for predicting the way nanocrystals ought to reflect their light, to name a few.
“The results are a perfect match with what we observe [in real life],” Milinkovitch said.
Milinkovitch also said that the cells were influenced by subjecting to solutions of varied concentration that made the cells either shrink or swell. These alterations changed the distances between nanocrystals and distorted their visible colors as predicted by researchers.
Nonetheless, only adult male chameleons change colors especially when they are faced with a rival male they want to bully away or to attract a female. Female and young chameleons have a dull complexion and has a much scaled down upper layer of iridophore cells according to Milinkovitch.
This research findings could help engineers and physicists to imitate the color changing abilities of chameleons and apply in to new technology such as appliances that eliminate reflections.
