The biology of colors

The animal world is very rich in colors; animals live in a colorful world, but we rarely stop to reflect on how that color is produced and perceived, or how it has evolved.

This very interesting topic, and decidedly less obvious than one might suspect, attracted the attention of Innes C. Cuthill and collaborators, who in a beautiful (and colorful) article published in the prestigious “Science” magazine report the current situation on what is already known about the functions of color in animals, and the research the group intends to undertake to study how color is used as a form of communication between individual animals and how it affects interactions with parasites, predators and surrounding environment.

The scientific study of colors

Given the complexity of the topic, it was necessary to involve experts from different fields, such as evolutionary biologists, behavioral ecologists, psychologists, optical physicists, visual physiologists, geneticists and anthropologists. In the last twenty years this field of research has expanded a lot, also thanks to technological advances - spectrophotometry, digital imaging, computational neuroscience, field studies and large-scale comparative analyzes - which will allow us to investigate this area with increasingly technical approaches.

The iridescent throat of the broad-tailed hummingbird (Selasphorus platycercus) changes dramatically in appearance from black to magenta depending on the viewing angle and/or the angle of illumination.

From an adaptive point of view, color has been (and still is) anything but irrelevant: many of the “colored” functions of animals are in fact the surprising and ingenious result of multiple evolutive pressures, such that only those who possessed certain characteristics could be suitable for survival in that particular environment.

In the article (of which we will cite only a few passages below, in addition to other curiosities) it is concluded that animal coloring mediates the relationship between an organism and their environment in different ways, including social signaling between individuals, defense against predators, parasitic exploitation, thermoregulation, protection from ultraviolet light.

Specimen of "peacock mantis shrimp" (Odontodactylus scyllarus), crustacean of Indo-Pacific coral reefs. The presence of as many as 16 cones (the cells that allow us to see different colors), unlike the human being who only has 3, gives these creatures the ability to recognize different types of corals and fluorescent or almost transparent prey/predators.

Coloring to hide