Beetle’s Scales Are Whitest, Most Efficient Light-Scattering Biological Material Known, Could Prove Basis for Brighter, Whiter Coatings and Materials

The physical properties of the ultra-white scales on certain species of beetle could be used to make whiter paper, plastics, and paints, while using far less material than is used in current manufacturing methods. The Cyphochilus beetle (image), which is native to South-East Asia, is whiter than paper, thanks to ultra-thin scales which cover its body. A new investigation of the optical properties of these scales has shown that they are able to scatter light more efficiently than any other biological tissue known, which is how they are able to achieve such a bright whiteness. The findings were published online on August 15, 2014 in an open-access article in Scientific Reports. Animals produce colors for several purposes, from camouflage to communication, to mating and thermoregulation. Bright colors are usually produced using pigments, which absorb certain wavelengths of light and reflect others, which our eyes then perceive as color. To appear as white, however, a tissue needs to reflect all wavelengths of light with the same efficiency. The ultra-white Cyphochilus and L. Stigmabeetles produce this coloration by exploiting the geometry of a dense complex network of chitin – a molecule similar in structure to cellulose, which is found throughout nature, including in the shells of molluscs, the exoskeletons of insects, and the cell walls of fungi. The chitin filaments are just a few billionths of a meter thick, and on their own are not particularly good at reflecting light. The current research, a collaboration between the University of Cambridge and the European Laboratory for Non-Linear Spectroscopy in Italy, has shown that the beetles have optimized their internal structure in order to produce maximum white with minimum material, like a painter who needs to whiten a wall with a very small quantity of paint.
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