Page "Amphibian" Paragraph 44

The skin colour of amphibians is produced by three layers of pigment cells called chromatophores.

These three cell layers consist of the melanophores ( occupying the deepest layer ), the guanophores ( forming an intermediate layer and containing many granules, producing a blue-green colour ) and the lipophores ( yellow, the most superficial layer ).

The colour change displayed by many species is initiated by hormones secreted by the pituitary gland.

Unlike bony fish, there is no direct control of the pigment cells by the nervous system, and this results in the colour change taking place more slowly than happens in fish.

Bright colours usually indicate that the species is toxic and is a warning sign to predators.