Most lobsters are a mottled brown color, but sometimes you can see a strange orange or blue lobster. And then, when lobsters are cooked, they turn bright red. Why is there such a rainbow of lobster colors?
As explained in this video from the American Chemical Society, lobsters eat a red pigment in their plant food called astanxanthin, which helps protect them against stress. This pigment is stored in a lobster's skin underneath its hard outer shell. But over time, the pigment begins to migrate into the shell, where different shell proteins alter the pigment to store it, changing its color. This creates a layer cake of lobster colors: the red skin at the bottom, a layer of blue pigment in the shell's bottom layer, and orange on the outside of the shell. When we look at a lobster, these colors combine to create the muddy brown color. But when a lobster is cooked in a pot of boiling water, the heat breaks down the blue and orange proteins in the shell—leaving just the bright red skin visible.
Watch the video to learn how scientists use multi-colored lobsters to study a shell disease caused by bacteria in the Northeastern U.S. ocean.