Colour Change
How it works and why it's used
Chameleons really are super cool. Their unique ability to change their colour whenever they feel it's necessary, to most anything they feel is necessary is so amazing, it's easily one of the icons that would come to most people's minds when they think of the "Wonderful World".
Unfortunately, the stereotype is a little bit different than the actual facts. Some chameleons can change colour but only a portion of their species, and only a few of these use it for camouflage. Though there's no need to fret, the truth is not all crushed hopes and dreams, and I'm going to tell you why.
Usefulness
Chameleons have many more uses for their colour changing ability than just camouflage. Many more. In fact, camouflage is one of the most uncommon uses for it. Mostly, males use their many colours to show off to females. In fact, it's more impressive to have a wider variety of colours.
A couple other important uses for their colours is, like courtship, intimidation (dark colours) and establishing dominance (light colours). Also, they can show their condition (temperature, health, physical condition), and sometimes emotions (they use a variety of colours to show different emotions).
Not only are there interactive uses, but there are some physical uses as well. There is camouflage, but there is an even cooler usage of it, much more interesting than hiding. Chameleons can use their colours to manage their temperature. They use darker colours to absorb more heat when cold, and lighter colours to absorb less heat and cool down. It doesn't even have to be symmetrical so they can even out heat when the sun is shining directly on one side of them.
How it Works
Chameleons change the colour of their skin with cells called chromatophores. They work by dispersing the pigments carried inside of them becoming a solid colour when its pigment are spread throughout it, pigment of which there are a few variations which change the chromatophores names altogether. These variations are quite different from each other and come in layers below a layer transparent skin.
Firstly there are xanthophores and erythrophores, of which only vary by their colour. They are yellow and red in colour respectively and are named by high amounts of one in a cell, seeing as they can be mixed in together a little bit.
Second come iridophores, which contain a bright blue-green iridescent pigment. These are made of plates of crystalline guanine (a part of the make-up of DNA) that diffract light to produce the iridescence of their colours.
The third and final layer is made up of melanophores, which by the name have eumelanin, a type of melanin of which is a dark brown. As melanin controls the darkness of our skin it controls the darkness of chameleons colours.
Chameleons use all these layers to make their colours by dispersing these pigments throughout the cell they're in. When the pigments are centered inside the cell, the cell seems transparent. When it's dispersed it is, like you would think, coloured. By varying the intensity of the pigment dispersion, using their nerves to do so, they can mix all sorts of colours to any use they require.
TOR FAGERLUND