A study by the University of Bristol has shown that the glitter of the spatula fish scales, the glittering formations around the eyes of a cuttlefish and the metallic effect of the cetonia carapace all have the same origin.
Physics meets biology. To explain this phenomenon, biologists have come to the aid of physics and in particular the so-called Anderson localization model, which according to the team of scientists Thomas Jordan, Julian Partridge and Nicholas Roberts explains the natural reflectors that characterize certain animals, such as these:
Brilliant disorders. Whether it is the silvery color of a carp, or the iridescence of an insect, this effect is the result of an evolutionary process on a nanometric scale (see From the Universe to the atom) which has allowed some animals to exploit the properties of waves luminous, as in the case of some fish that use the crystals present in their scales to camouflage themselves in shallow waters. What scholars have discovered is that all "bright" animals have one thing in common: the difference in thickness between the crystalline layers of their outermost part (scales, shells, wings, etc.).
Nicholas Roberts explained to the BBC that "when light filters in and meets the irregularity between the different layers, the light waves interfere with each other" or "bounce between the various layers" and eventually come back.
Help from nature. One of the most interesting aspects of this study is that such natural surfaces are often more reflective than artificially created ones. Understanding how they work could therefore lead us to reproduce highly reflective materials and, for example, make LED lights even more efficient.