How do animals produce black, white, red, blue, and green colour signals?

Animals produce colour through two primary mechanisms: chemical pigments (biochromes) and physical structures (schemochromes).1

Pigmentary Colours

Pigments reflect or transmit specific portions of the solar spectrum.1
* Black: Primarily produced by melanins, which are dark, light-absorbing polymers.2
* Red: Often derived from carotenoids, which are pigments obtained through diet. Hemoglobins also contribute to red and pink hues in skin and tissues. Additionally, specific porphyrins can produce deep red colours.3456
* White: While often resulting from the lack of pigment, specialized cells called leucophores can contribute to white coloration.7

Structural Colours

Structural colours arise from submicroscopic structures that fractionate light.1
* Blue: Typically produced via the Tyndall effect, where finely dispersed particles scatter shorter blue wavelengths of light, which are then reflected back while longer wavelengths are absorbed by underlying melanin.8
* Green: Most green colours in animals are not produced by green pigments. Instead, they result from the combination of structural blue light scattering through an overlying layer of yellow carotenoid pigment. Exceptions exist, such as the green pigment turacoverdin found in some birds.86