|False-coloured scanning electron|
micrograph of arrays of nanofibres
found in barbs of little penguin
feathers. Photo by Liliana D'Alba.
The researchers used light and electron microscopes to examine wing and back feathers of little penguins and found they contained massive numbers of fibres that were nanometres in diameter and arranged side-by-side. The neat, organised parallel alignment and tiny scale of the fibres cause light scattering in such a way that creates a blue hue.
While the light scattering of nanofibres is responsible for the blue colour of the skin of some birds and other animals such as mandrills, this is the first time is has been found as the source of the colour blue in feathers.
Dr Matthew Shawkey, one of the researchers, said, "For 30 years it has been thought that blue colours in feathers are only produced by cells of feather barbs in spongy layers, or matrices of keratin with nanometre-scaled pores in them. These results show that we should never stop looking just because we 'know' how something is made."
UA researchers solve colour mystery of blue-feathered penguins, 9 February 2011, The University of Akron News
Biology Letters citation
Colour-producing β-keratin nanofibres in blue penguin (Eudyptula minor) feathers. Liliana D'Alba, Vinodkumar Saranathan, Julia A. Clarke, Jakob A. Vinther, Richard O. Prum and Matthew D. Shawkey. Biology Letters. 9 February 2011.