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How do chromatophores help produce reptile colours?

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A painted turtle (Chrysemys picta) with a dark shell and red and yellow markings rests on a rock near water, surrounded by green aquatic plants. — reptile Painted turtle (*Chrysemys picta*).

Reptilian colours are produced through a combination of pigment-containing cells in the skin and the physical properties of the skin itself.12

In the dermis, three primary types of chromatophores contribute to these colours:
* Melanophores: Contain the black or brown pigment melanin.31
* Xanthophores: Contain yellow pigments.31
* Iridophores: Contain reflecting platelets of colourless guanine, which produce colour through the diffraction of light.1

Additionally, melanocytes located in the epidermis also play a role in determining the animal's overall colouration. The distribution and concentration of these pigments allow for fixed patterns, which often serve as camouflage to help the animal blend into its natural habitat, or for rapid colour changes in certain species like chameleons and anoles. In these instances, the concentration of pigment granules within melanophores is regulated by a complex interaction of the nervous system, hormones, and temperature, causing the animal to appear lighter when pigment is concentrated or darker when it is dispersed.14