A chameleon changes its color to adjust its body temperature to the outside temperature. They change color by changing the arrangement of certain skin cells called iridophores. These cells have nanocrystals that reflect light of different wavelengths, depending on their physical orientation.
The color-changing ability of chameleons has always intrigued human beings. We often think about how cool and easy life would be if we could change our colors, blend in with our surroundings, and camouflage ourselves just like a chameleon can. It would definitely help us escape from awkward situations more easily!
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How Does a Chameleon Change its Color?
Unlike octopuses and cuttlefish, who change color by moving around the pigment in their cells, chameleons have specialized cells called iridophores that do the job for them. A 2015 study published in Nature Communications looked at how five adult male, four adult female, and four juvenile panther chameleons changed their colors. They found that chameleons have two layers of these iridescent cells—iridophores. These iridophores have pigments and nanocrystals within them that reflect light of different wavelengths. The chameleon changes its color by exciting or relaxing its skin, changing the density of the upper layer of iridophores.

The red color is caused by a red pigment (erythrophore) and the green is the result of a yellow pigment (xanthophores), with the blue wavelength being reflected from the iridophores. (Credits: Fedor Selivanov/Shutterstock)
Why Does a Chameleon Change its Color?
Chameleons don’t change their color for camouflage, as most people think. They can’t perfectly match your crazy pink curtains or blend into your blue couch. As much as Pascal from Disney’s Tangled might change his colors on whim, alas, that is fiction for real chameleons, although their skin color does serve some camouflaging purposes. Chameleons spend most of their time in trees, high up amidst the brown branches and green leaves. Their own green and brown hues do allow them to blend into the leafy background, but their ability to change color isn’t intended for that. Chameleons, as recent research has found, change color for two main reasons—to communicate and to control their temperature. Animals have evolved different ways to communicate with one another. Humans primarily use language, fireflies use light, and chameleons use color. The chameleon’s color change can indicate its mood. An angry chameleon will have a darker color, whereas a chameleon in a relaxed mood will have a lighter color. A 2013 study looked at the coloration in male chameleons during competition with other males. The researchers reported that different coloration patterns in different body regions sent different signals to their competitors. Males with a darker head were more likely to win fights, while those with brighter stripes were more likely to approach their opponent first during the competition.

It is usually the male chameleons that perform color change, either to win a mate or warn predators. (Credits: reptiles4all/Shutterstock)

The iridophores in these chameleons help decrease the absorption of sunlight, which is crucial for survival. (Credits: Andrey Lavrov/Shutterstock)
Color change in chameleons and other animals still isn’t fully understood. The range of occasions for which chameleons adapt their colors is still being outlined. The more exciting question seems to be how such color-changing evolved in the first place. From complex nanocrystal lattices to pigment dispersal in the blink of an eye, the intricate ways that animals change color is stunning, fascinating and downright magical!