To compensate for not having an internal bone structure, certain insects develop an exoskeleton to protect their soft internal tissues. And the Buprestidae family of beetles, also known as Jewel Beetles, boast a resplendent metallic armour-like exterior. Their colourful glossy finishes are a result of dozens of layers of chitin – a carbohydrate structure made from sugar molecules, similar to cellulose. Chitin contributes to the fabrication of shells for other insects, as well as crustaceans like lobsters and shrimp.
Scientists are learning that a Scarab beetle’s chitin consists of up to seventy individual layers that progressively get thinner as they are added. The transparency of each coating scrambles light wavelengths, causing the light to refract in interesting and different ways. This produces an iridescent metallic effect that, upon first glance, seems entirely unnatural. It is worth noting that metallic automotive paint, similar to chitin, is applied in layers, creating transparency and refraction of light – not to mention strength. Perhaps the next time you see a VW Beetle you will think of it in a new light.