how the lizards change their colour ?

Answer 1

They have contractile cells bearing pigments in the cytoplasm. They are called chromatophores. They lie in the upper part of the dermis.They are under the influence of melanocyte stimulating hormone. They contract and expand leading to a change in skin colour.Light and dark can also influence these cells. Photoperiod has a bearing on pineal gland, which secretes melatonin having an effect on pigmentation of the skin.

Answer 2

Only a few chameleons and lizards can change color

There is a wide spread opinion that the chameleon changes its color according to its environment, turning itself invisible to its predators.

An individual able to shift its behavior in accordance with different persons is compared to a chameleon. But is that so?

Science does not confirm this idea at all.

Actually, the chameleon is constantly changing its color. Chameleons possess in chromatophores (cells that give skin’s color) two types of pigments: one black (melanin) and another one, of various colors. Chromatophores retire or display their ramifications, changing this way their color.

Their movements are under the control of nerves or hormones (adrenaline secreted by the adrenal gland and hormones of the hypophysis). These colors respond perfectly to the needs of their arboreal life: 130 species of chameleons out of 156 live in trees. Colors displayed by the chameleons vary from gray to whitish, black, vivid green, green-yellow, olive or blue.

Here are some pictures:
http://images.search.yahoo.com/search/images;_ylt=A0geu8G3cnFGApoACtVXNyoA?ei=UTF-8&p=chameleon&fr=slv8-hptb5&fr2=tab-web&fr=slv8-hptb5

Other animals like octopuses and flounders can change color too

Answer 3

Specialized skin cells called chromatophores that translocate pigment based on hormonal or environmental signals.