Biological pigment

Major chemical classes

Common pigment families include porphyrins (including heme and chlorophyll), carotenoids (yellow, orange and red terpenoids), flavonoids such as anthocyanins (water-soluble plant pigments producing red, purple and blue hues), and melanins (dark, often brown or black polymers). Each class absorbs light at characteristic wavelengths, which determines visible color and influences physiological roles. For example, chlorophyll is central to light capture in photosynthesis, while carotenoids contribute both to light harvesting and photoprotection.

Biosynthesis and inheritance

Pigments are produced by metabolic pathways encoded in genomes; biosynthesis often involves multi-step enzyme reactions that convert common biochemical precursors into colored molecules. Some organisms also modify pigments after synthesis by conjugation, glycosylation or polymerization. In animals, coloration may combine endogenous synthesis with dietary acquisition—many birds and fish obtain carotenoids through food. Genetic variation, regulation of biosynthetic genes and environmental factors (light, temperature, nutrition) shape pigment expression.

Ecological roles and signaling

Colors created by pigments serve multiple ecological and behavioral functions. In plants and animals, pigments alter appearance to influence appearance and behavioral responses of other organisms: cryptic coloration and camouflage conceal individuals from predators, while bright patterns often function as warning signals that advertise toxicity or unpalatability. Floral pigments attract pollinators and facilitate pollination, sometimes using wavelengths outside human vision such as ultraviolet.

Protection and physiological roles

Some pigments have protective or metabolic roles beyond visible signaling. The widespread pigment melanin can absorb short-wave light and reduce damage from sunlight and ultraviolet radiation, protecting tissues and DNA. Other pigments act as antioxidants, photoprotectants or components of light-harvesting complexes. Hemoproteins and other colored cofactors can also play essential roles in respiration, photosynthesis and enzymatic chemistry.

Distinction from structural colour

Pigment-based color differs from structural colour: pigments produce the same hue regardless of viewing angle because color arises from molecular absorption. Structural colour arises from microscopic physical interactions such as reflection, diffraction or scattering and can produce angle-dependent effects and iridescence. Many animals appear colorful through combinations of pigments and structural elements—for example, the same wing may show pigment patterns alongside shimmering iridescent regions.

Human uses and scientific importance

Humans have used biological pigments for millennia as dyes, paints and food colorants. In modern biology, naturally colored proteins such as green fluorescent protein and its derivatives are indispensable markers in cell and molecular research. Pigments are studied for agricultural improvement (flower and fruit color), nutritional enhancement (carotenoids as provitamin A sources), medical diagnostics and materials science, including natural UV filters and antioxidant applications.

Measurement and study

Pigment analysis commonly uses spectroscopy, chromatography and microscopy to identify chemical structure, concentration and localization. Spectral properties reveal absorption peaks; chromatography separates components; imaging locates pigments within tissues. Studies also investigate biosynthetic gene networks, ecological functions and evolutionary patterns that have produced convergent and divergent color strategies across taxa.

Notable considerations

• Some pigments are produced de novo by the organism, others are sequestered from diet or symbionts.
• Color perception depends on the observer’s visual system; ultraviolet patterns visible to pollinators may be invisible to humans.
• Pigments may serve multiple roles simultaneously—communication, protection and metabolism—so function must be inferred cautiously.

Because pigments intersect chemistry, ecology and evolution, they remain an active area of research with applications ranging from crop breeding to biotechnology. For concise introductions to specific pigments and concepts, see entries and resources on biological pigment, chlorophyll, photosynthesis, and topics such as camouflage, warning coloration and reflection.