Butterfly wings are one of the most beautiful sights in nature; some species of the fluttering insects sport fantastically colored patterns and designs on their wings that catch the sunlight in spectacular ways. It has long been known that these colors were not produced in the expected way, for example through pigmentation, but in a paper in the June 15, 2010 edition of the Proceedings of the National Academy of Sciences, lead researcher Vinodkumar Saranathan and team used x-ray technology to demonstrate the ingenious secret behind the insects’ striking wing coloration.
Cells Like Crystals
Using small angle x-ray scattering, or SAXS, the team were able to produce three-dimensional images of single cells upon the wings of five different types of butterflies, all of which were drawn from two families, the Papilionidae and the Lycaenidae. Previously, butterfly wings had only been studied using a two-dimensional electron microscope; the x-ray scattering technique allowed the cells of the wings to be examined in three dimensions for the first time.
The cells, or nanostructures, thus revealed were of a type known as gyroids, which are vaguely pinwheel-shaped structures that refract sunlight similar to the way a crystal does.
Double and Single Gyroids
These gyroids are quite common in many different types of plants and animals, though the most common are layered structures called double gyroids. The researchers, however, discovered that the butterflies’ wings are composed of much rarer single gyroids, structures which allow all wavelengths of light but one to pass through; the one wavelength that reflects off the structure gives the wing its hue. Smaller gyroids produce colors more in the blue end of the spectrum, while larger gyroids shade toward red.
Future Uses for Butterfly Technology
Creating a synthetic single gyroid has long been a goal of photonic crystal engineering, but evidently natural selection arrived at the solution millions of years ago, as is so often the case. Now that the structure of single gyroids in butterfly wings has been studied and described, it is hoped that the natural structure can be used as a template to produce a human-made version, which not only could produce colors that never fade but could also have applications in other areas of optics and in solar energy.
Sources:
Moskowitz, Clara. "Source of Shimmering Butterfly Wing Colors Revealed". LiveScience. June 14, 2010
Saranathan, Vinodkumar et al. "Structure, function, and self-assembly of single network gyroid (I4132) photonic crystals in butterfly wing scales". Proceedings of the National Academy of Sciences. June 14, 2010
Jenny Ashford - Jenny Ashford is a writer and graphic artist from central Florida. Her main area of interest in her Suite 101 articles is science, with a ...
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