Many animals, such as squid and chameleons, alter their colours bychanging the size of pigment-carrying cells, but the Panamanian goldentortoise beetle Charidotella egregia has a completely novel wayof going from metallic gold to matt red. Jean Pol Vigneron andcolleagues from the University of Namur in Belgium have found that thebeetle has a layered shell, and that each layer reflects a differentcolour and bears patches of nanoscale grooves.
This particular beetle normally has body fluid between these layers,filling the grooves and giving rise to mirror-like reflections thatresult in the insect's metallic gold appearance. When the fluid iswithdrawn, the mirror-like effect disappears and the layers act aswindows, displaying the red pigment below. This is an entirely novelmechanism for the control of colour and has the potential to give riseto innovative new display technologies.
Source: cerncourier.comAdded: 28 November 2007