Dear Blue Lobster:
How did they make the Lobster blue?
Dear Gentle Sir:
There are many species of lobsters, crayfish, crabs and other decapods in nature that occur blue naturally or can be made to turn blue with some effort. Indeed, the same holds true for any color morph. Among the methods for inducing color morphs, such as eugenics, lighting, dyes, psychotherapy, painting, and oxygen deprivation, simple selective breeding is the most widely-practiced.
In all crustaceans, different concentrations of pigments in their exoskeleton are responsible for their color. These varying color patterns are controlled by the animal's genes, which are the results of generations of adaptation and breeding. Selective breeding then, just as with dogs or cats, can be used to induce different color patterns.
By breeding two blue crayfish parents, for instance, more than half of the resulting brood will be blue. After several generations of blue-breeding, not only will entire broods be blue (expressing the dominance of the blue color), but different shades of blue will start to emerge.
Likewise, crossing two different color crays can result in a third color, though it is much more difficult. In breeding a pair of Lousiana Crayfish (Procambarus clarkii), one red and one blue, most of the brood will be red since it is the dominant color. Some, if any, of the offspring will be blue. Once in every few hundred generations, however, the two color expressions will merge and create a purple crayfish. Due to the fleeting nature of that morph, creating a breeding population of purple clarkiis is impossible.
It's also possible to change a crustacean's color patterns. The Rusty Crayfish (Orconectes rusticus) is usually a flat green-grey color with red spots on its sides and the tips of its claws, but thanks to selective breeding by hobbyists a speckled red-and-green line has been established and is now known as the Christmas Cray. Conversely, the Peacock Shrimp (Lysmata cyanea) is a bright blue with pink pleopods and yellow mottling on its claws but has been bred into a simple neon-blue morph.
Selective breeding for color morphs is something you can try at home. Have two different colors of the same species? Force them to breed and see if you can spot a new color in the hatchlings. Want to promote a certain pattern of stripes? Pick the two specimens and mate away! Who knows? Perhaps you could be the first person to unlock some unseen morph, like a red-and-yellow checkerboard crab or a purple-and-pink polka-dotted crayfish. Good luck!