Dicrota

Dicrota (from di- + Greek krotos - blow) is an optical phenomenon in which the color of the body appears different depending on the angle of view. This is due to the anisotropy of the body surface, that is, the difference in optical properties in different directions.

The cause of dikrota is most often the microscopic structure of the surface. For example, in the plumage of birds it is due to the special structure of the feathers. Light hitting the feather from different angles is refracted and reflected differently from the microscopic teeth. This creates the color changing effect.

The phenomenon of dicrota is characteristic of feathers, fish scales, and the wings of some butterflies. It is used in nature for camouflage and signaling. Scientists also use dicrotic structures to create optical sensors and information display devices.