Biological Pigments
In biology, a pigment is any colored material of plant or animal cells. Many biological structures, such as skin, eyes, fur and hair contain pigments (such as melanin). Animal skin coloration is often achieved with specialized cells called chromatophores, which in animals such as the octopus and chameleon can be controlled to vary the animal's color. Many conditions affect the levels or nature of pigments in plant, animal, some protista, or fungus cells. For instance, Albinism is a disorder affecting the level of melanin production in animals.
Pigmentation is used in organisms for many biological purposes including Camouflage, Mimicry, Aposematism (warning), Sexual selection and other forms of Signalling, Photosynthesis (in plants), as well as basic physical purposes such as protection from Sunburn.
Pigment color differs from structural color in that it is the same for all viewing angles, whereas structural color is the result of selective reflection or iridescence, usually because of multilayer structures. For example, butterfly wings typically contain structural color, although many butterflies have cells that contain pigment as well.
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