How do Chameleons change colour ?

Parsons Chameleon

 Although many people have a misconception that the Chameleons change of skin colour is targeted toward blending with the surroundings, that is not strictly true.  The main reasons for skin colour change include mating behaviour, emotion exhibition and temperature adjustment.  For instance, if a male Chameleon tries to attract females, it may exhibit lighter and brighter skin colours.  On the other hand, since Chameleons do not possess the ability to maintain body heat, the lizard can achieve optimal temperature with the help of darker shades to absorb heat, and lighter shades to release heat (Bates, 2014).  The range of colours is enormous, including blues, reds, greys, pinks, yellows, purples and more.  However most species of Chameleons can only change between a limited numbers of colours (Raxworthy, 2014).

For example most Veiled Chameleons will change colours mainly using greens, yellows and dark greys or black. Going back to the point about whether or not Chameleons can change colour to match their surroundings, we did find a study from the New Scientist that shows some species of chameleons like the Smith’s Dwarf Chameleon can actually change their colours to almost match their surroundings when under threat from different species. In particular birds and snakes.
www.newscientist.com/article/dn13944-chameleons-finetune-camouflage-to-predators-vision.html#.UfEwGY21GBQ

How does the Chameleon change its colours ?

On a physical level, colour changes in Chameleons involves skin cells. Chameleons have outer skin that is transparent, and there exist a number of skin layers having special cells known as chromatophores. When signals are received, these cells expand and contract.  Since these cells contain colour pigments, expansion and contraction results in different skin colours (Clark, 2005).  For instance, if red cells become fully expanded, then the skin colour of the Chameleon appears to be red.  On the other hand, when green cells seem to expand, a Chameleon appears to be green.

 

References:

1) Bates, Mary.  “How Do Chameleons Change Colours?” Wired.  Howard S.  Mittman, 11 April 2014.  Web
2) Clark, Rulon.  “How do chameleons/anoles change colours?” 
Cornell Center for Materials Research (CCMR).  Cornell University, 27 January 2005.  Web
3) Raxworthy, Christopher.  “A Truly Bizarre Lizard.” 
PBS.  Public Broadcasting Service.  Web

Images:

1) Main image supplied by Dan Fegent