Pigment

Pigment is a colored substance that is found in all living organisms and gives them color. It consists of molecules that absorb light of a certain wavelength range and reflect other waves outward. Pigments play an important role in photosynthesis, skin pigmentation, visual perception and many other biological processes.

Biological pigment can be:

A chromophore is a molecule that absorbs light and transmits it to other molecules. Examples of chromatophytes are carotenoids (red and orange pigments) in plant cells and melanins (brown and black pigments) in human skin.

A photoreceptor is a molecule or complex of molecules that is sensitive to light and can generate electrical signals in response to light. Photoreceptors are the basis for vision and hearing in animals and other organisms, and they are usually found in the nervous system or in the pigment layer of the eye.

Bioluminescent - that is, producing light when it hits a light cell. The green light is due to the symbiotic activity of a symbiont of the genus Rickettsia, and some ultraviolet marine life, such as crustaceans and fish, can use bacteriorhodopsin as a photosensitizer.

Unlike simple dyes, biological pigments are highly stable and protective.