The Standard Two composite class of Rangiwahia School asks :-

How do Chameleons change colour?

Alison Cree, a zoologist at the University of Otago, responded.

Chameleons are African lizards with long, sticky tongues. They can change colour very rapidly, from green to brown in a few minutes. To understand how they do this, we need to know about special cells (called chromatophores) in their skin. These cells contain pigments (coloured substances). Some contain yellow, red or orange pigments, and some contain reflecting crystals that look silvery. The pigment can move around in the cell. If all the pigment is in the middle of the cell, we can't see much of it and the animal looks light in colour. If the pigment is spread throughout the arms of the cell, the animal looks darker.

The pigment-containing cells are in layers in the skin. Some layers can cover up other layers. The exact colour of the skin that we see depends on which layer is covering another layer, and whether the pigment in each layer is spread out or clumped. Various combinations of the main pigment-containing cells listed above can make the chameleon's skin appear green, blue, brown, black, white or yellow.

What makes the chameleon change colour? Different amounts of heat and light can do this. If you covered part of the chameleon's body with your hand to stop light falling on it, you would soon see the shape of your hand on the lizard's skin in a different colour to the rest