biochrome

A biochrome is a natural pigment found in plants or animals that gives them color. These pigments are chemical compounds that selectively absorb and reflect light, creating the colors we see.12

Biochromes can be broadly categorized into two groups: nonnitrogenous and nitrogenous pigments.2

• Nonnitrogenous pigments include carotenoids, quinones (like benzoquinones, naphthoquinones, anthraquinones, and polycyclic quinones), and flavonoids. For example, naphthoquinones can appear as yellow, orange, red, or purple crystals and are found in plants and some animals.234
• Nitrogenous pigments include tetrapyrroles, such as porphyrins (like chlorophyll and heme) and bilins (like bilirubin and biliverdin). Melanins, which are dark pigments found in skin, hair, and feathers, are also nitrogenous.25

These pigments can be located in nonliving structures like hair or feathers, or within living cells called chromatophores. Chromatophores can disperse or concentrate biochromes, allowing for rapid color changes in animals like cephalopods, crustaceans, insects, fish, amphibians, and lizards. Hormones and nerves often control these physiological color changes.26