By Anupum Pant
If you have ever handled a butterfly, you must have noticed that the wings of a butterfly leave a kind of dust on your fingers. If you look closely, using a scanning electron microscope of course, you’ll find that these dust like things are in fact scales! Butterfly has scales on in wings. Whatever purpose it serves to the butterfly.
The name Lepidoptera means “scale wing” in Greek.
The scales, so tiny themselves, have much tinier grooves on them. The grooves are so evenly spaced that they match the wavelength of a particular colour of light and that is what gives them their distinctive colour. May be some of it comes from the pigment too, but most of the colour comes only from the grooves, the topology of it. The colour comes from the nano-structure on the surface of a tiny tiny scale. Amazing!
We indeed have a lot to learn from the world around us.
This is clear when you fill the grooves using a liquid like propanol. The colour disappears as the grooves are filled with the liquid. Once the liquid evaporates, the colours come back to life.
These colours that come due to the topology of the scales serve various purposes like camouflage, warning, attracting mates, absorbing heat by looking darker and deceiving predators.