Iridescence

Examples of iridescence include soap bubbles, feathers, butterfly wings and seashell nacre, and minerals such as opal.

Iridescence can for example be due to thin-film interference, the functional analogue of selective wavelength attenuation as seen with the Fabry–Pérot interferometer, and can be seen in oil films on water and soap bubbles.

[7] In the case of diffraction, the entire rainbow of colours will typically be observed as the viewing angle changes.

In biology, this type of iridescence results from the formation of diffraction gratings on the surface, such as the long rows of cells in striated muscle, or the specialized abdominal scales of peacock spider Maratus robinsoni and M.

[18]The feathers of birds such as kingfishers,[19] birds-of-paradise,[20] hummingbirds, parrots, starlings,[21] grackles, ducks, and peacocks[15] are iridescent.

[25] Many groups of plants have developed iridescence as an adaptation to use more light in dark environments such as the lower levels of tropical forests.

The leaves of Southeast Asia's Begonia pavonina, or peacock begonia, appear iridescent azure to human observers due to each leaf's thinly layered photosynthetic structures called iridoplasts that absorb and bend light much like a film of oil over water.