"Once upon a time, there was a mouse that wasn’t really a mouse, with fur that wasn’t really fur but photonic crystals. "
Polychaetes of the genus Aphrodite are large, carnivorous, but slow-moving, animals found in oceans and estuaries around the world. They're up to 20 centimeters long and eat other worms even bigger than themselves. As well as bearing parasites - Veneriserva pygoclava - themselves several times longer than their host.
They're a lot plumper than most worms, quite oval in fact, and covered in felt-like fur.
I used to wonder why they used the name of the Goddess of Love to describe a fleshy mound covered in fur.... then I went "Oh. *blush*"
"The sea mouse attracted our attention because its iridescence is extraordinarily marked for a bottom-dwelling sea creature," said Ross C. McPhedran, a professor of physics at the University of Sydney. His team member, Andrew R. Parker of the University of Oxford in the UK, specializes in the study of structural coloration, including natural diffraction gratings found in the 500-million-year-old fossil oddities of the Burgess shale in the Canadian Rocky Mountains, and suspected that the creature employs such a technique.
That fur proves yet again that whatever humans can think of, nature got there first. In this case it's photonic crystals.
In the photo above they're shining blue & yellow. In the photo below they're a beautiful blue. If the light is coming in perpendicular to the axis, they're a brilliant red.
Photonic crystals, first produced by man only in the last decade, have an internal structure that traps and reflects light with extraordinary efficiency. They're currently trying to perfect photonic optical fibers. Because they require drilling nanometer-scale holes in silicon, they're extremely difficult to produce.
Aphrodite produces them in quantity, and more evenly than the other natural photonic crystal - opal - ever was.
The spines are essentially hollow tubes, with the outer walls consisting of tiny cylinders of chitin, the same structural material found in lobster and crab shells, arranged in regular, close-packed layers. These layers - 88 of them - are what give the spine its crystalline quality, reflecting light as it passes through it.
Sea mice fur has almost 100% reflectance, and it's tunable by adjusting the angles they hold the hairs at. Thus making them conspicuous not matter how poor the light is. That way they can warm predators in advance that they are not a pleasant dining experience. Some of the hairs are sharp as well as beautiful. More photos, SEMs, and close-ups, here.