http://www.washingtonpost.com/wp-dyn/content/article/2005/06/15/AR2005061502231.htmlWatermen say that female blue crabs "paint their fingernails," meaning the tips of their claws turn bright red as they age. The male crabs, on the other hand, have sky-blue claws -- a sign as masculine as a mustache in the world of crustaceans.
So when Robbie Watson dumped out a crab trap and found a specimen with one red claw and one blue one, the discovery stopped him.

