Difference in changing of colour in eastern garden lizard and chameleon

Many species have colour changing ability such as crustaceans,insects, squids, octopus ,cuttlefish and others ,frogs lizards and fish can change colour .
These animals have one thing in common,they are ectotherms and ectotherms have special cells that are able to change colour.
   

                     Chameleons

Chameleons are known for their changing colours. Some species of chameleon are able to change their skin colouration.

Different spicies have different function and purpose to change their skin colour.

Camouflage ( to change them selves a/c to their environment ) is one of the function of changing coulor .Not every spicies of chameleon change colour for camouflage.

Some use their colours for social signaling and in reaction to temperature and other conditions.

The relative importance of these functions varies with circumstances as well as spicies.

Chameleons tend to show brighter colour when showing aggression and darker when they give up to other chameleon.

The desert  living namaqua chameleon change its colour for thermoregulation,it become black to absorb more heat and change to lighter colours to reflect light during Sunny days .

     Mechanism of changing colour

Chameleon skin has a superficial layer which contains pigments and under the layer are cell with guanine crystals . chameleons change colour by changing the space between the guanine crystals which change the wavelength of light reflected off the crystals which change the colour of the skin .

           Oriental garden lizards

Oriental garden lizards or blood sucker also has capacity to change their colours. The colour of lizards is mud yellowish colour and of brownish and greyish olive colour to light brown colour . 

The mechanism of changing colour in these lizards is may be as same as chameleons but as far as I know garden lizards can not change colours for camouflage instead they change their skin colour for-
* Signal other lizards.
* And only male lizards can change their colour.
*Sometimes changing confined to head and other times diffused to whole body .
*During breeding seasons head of males become orange or red to impress the female and sometime they change in combination of black orange and yellow colour and sometimes they become totally grey or dull colour .
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