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Biological pigments, also known simply as pigments or biochromes[How to reference and link to summary or text] are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments. Many biological structures, such as skin, eyes, fur and hair contain pigments such as melanin in specialized cells called chromatophores.
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.
- Heme/porphyrin-based: bilirubin, hemocyanin, hemoglobin, myoglobin
- Light-emitting: luciferin
- Proteinaceous: phytochrome, phycobiliproteins
- Polyene enolates: a class of red pigments unique to parrots
- Other: melanin, urochrome,
Pigments in animals
Pigments in animals may serve to protect tissues from ultraviolet radiation, such as melanin in the skin. Pigments may also aid in sexual reproduction, identifying species and gender of animals to potential mates, or signalling readiness to breed.
Pigmentation is used by many animals for protection, by means of camouflage, mimicry, or warning coloration. Chameleons use pigments to blend into their surroundings by controlling the absorption levels of the electromagnetic spectrum.
Diseases and conditions
A variety of diseases and abnormal conditions that involve pigmentation arise in humans and animals, either from absence of or loss of pigmentation or pigment cells, or from the excess production of pigment.
- Albinism is an inherited disorder characterized by total or partial loss of melanin. Humans and animals that suffer from albinism are called "albinistic" (the term "albino" is also sometimes used, but may be considered offensive when applied to people).
- Lamellar ichthyosis, also called "fish scale disease", is an inherited condition in which one symptom is excess production of melanin. The skin is darker than normal, and is characterized by darkened, scaly, dry patches.
- Melasma is a condition in which dark brown patches of pigment appear on the face, influenced by hormonal changes. When it occurs during a pregnancy, this condition is called the mask of pregnancy.
- ocular pigmentation is an accumulation of pigment in the eye, and may be caused by latanoprost medication.
- Vitiligo is a condition in which there is a loss of pigment-producing cells called melanocytes in patches of skin.
- ↑ Rang, H. P. (2003). Pharmacology, Edinburgh: Churchill Livingstone. Page 146
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