How does a Chameleons colour change work and how does it activate it? Also, is there any colours it struggles with and can it change into colours beyond our visible spectrum?
In: Biology
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Chameleons aren’t the masters of color and camouflage – for that you need to go to the octopus, the cuttlefish and the squid.
Chameleon are mostly greens or browns and shift to lighter and darker colors. Some do have red or yellow markings as well and they have UV markings as well. When they get angry or threatened then their color changing goes into overdrive and they go very dark.
But Chameleons are born with particular markings / pattern and they can’t change those – their color changing is restricted to lightening or darkening their existing pattern.
Chameleons use two systems for color change. To explain this first you need to know the way color works in chameleon skin (and really the skin of many animals). There are three kinds of pigment cells. Melanophores basically control how dark or black an animal looks. Iridophores are tiny crystals that scatter light, and based on the arrangement of the crystals, the light scattered can show an array of colors from blue to red. Finally, there are xanthophores which contain yellow and red pigments.
Chameleons can expand or contract the melanophores, which causes them to become lighter or darker (basically they either spread out the black pigment into a blotch or concentrate it into a little dot). Lots of other animals can do this too (most fish, for example). But chameleons can _also_ control the crystals in their skin and change what hue they reflect. By controlling both these things they can change or alter their color.
Contrary to what you often see on TV, they aren’t able to just arbitrarily mimic any color, although they are usually pretty well camoflaged in their resting color. They can change color to absorb more heat from sunlight and especially to make displays at each other. Different species and individuals have different color patterns they display. Think of it less like a camoflage suit and more like one of those billboards which shows a series of ads.
Some chameleons have UV markings but I’m not sure if they can change them or not.
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