Structural Colouration in Nature

Nature is surprisingly colourful! Many things, like plant leaves, beautiful flowers or even carrots, are colourful because of pigments: small molecules which absorb particular colours. However, there is another way to appear vivid and vibrant, and even gaudy!
This alternative strategy is known as “structural coloration”, and it uses colourless building blocks instead of relying on small colourful molecules! This beetle is bright, brilliant, and colourful because its shell is made of building blocks organised in a helix-like structure, a little bit like a spiral staircase. The building blocks themselves are not colourful but the way they are arranged on the nanoscale (a length scale millions of times smaller than our everyday world), allows them to interact with light in unusual ways. For example, if you look at this beetle through 3D glasses, like you would get at the cinema, it looks colourful... but only if you look through the correct eye!
This is because the 3D glasses filter the light. The left lens allows only the type of light which spirals in the same direction as the colourful beetle’s shell, while the right lens allows only the type of light which spirals in the opposite direction. So, if you close your left eye and look only with your right eye, while wearing cinema glasses, the beetle appears dull and dark! We hope that one day we will be more like these beetles: using materials which are colourful and vibrant yet organic, natural, and sustainable.