The bright red shell of a cooked lobster is the image most people associate with the crustacean, making the appearance of a live one something of a mystery. The color of a live lobster is a complex biological feature that serves a functional purpose, allowing it to blend into its surroundings for survival. This difference in appearance is a result of a chemical process that only heat can trigger.
The Standard Camouflage
The vast majority of live lobsters exhibit a dark, mottled coloration that is perfectly suited for life on the ocean floor. American and European lobsters are typically a mix of greenish-brown, bluish-black, or muddy green when they are pulled from the water. This standard appearance is an effective form of camouflage. The dark, patchy coloring allows the lobster to disappear against the substrate of rocks, mud, and seaweed where it lives and hunts.
This low-visibility coloration is due to a combination of pigments stored within the lobster’s shell. These pigments are arranged in layers and bound to proteins. This arrangement produces the dark, non-reflective shell surface. The result is a creature that is nearly invisible to both predators and prey in the dim light of its habitat.
Why Lobsters Turn Red When Cooked
The dramatic shift to a brilliant red color upon cooking is a chemical reaction involving two key molecules. Lobsters acquire a naturally red/orange pigment called astaxanthin from their diet, which is a type of carotenoid. In a live lobster’s shell, the astaxanthin is tightly bound to a protein complex known as crustacyanin. This binding process physically twists the astaxanthin molecules, which changes how they reflect light, effectively masking the pigment’s natural red color and producing the dark, muted camouflage.
When the lobster is exposed to high heat, such as in boiling or steaming water, the crustacyanin protein is denatured. Denaturation is the process by which a protein loses its original structure, causing it to unfold and break down. As the crustacyanin breaks apart, the astaxanthin pigment is released from its tight bond with the protein. Once freed, the astaxanthin reverts to its natural, stable state, allowing its inherent bright red-orange color to become visible on the shell.
Understanding Rare Genetic Colors
While the dark, mottled color is the standard, a small number of lobsters display rare, vibrant colors due to genetic anomalies. These color variations occur when a mutation affects how the astaxanthin is produced, stored, or bound to the crustacyanin protein. The most frequently reported anomaly is the bright blue lobster, which occurs in approximately one in every two million lobsters. This blue hue results from a genetic defect that causes an overproduction of the crustacyanin protein, intensifying the blue coloration that is usually only a component of the dark camouflage.
Other rare colors include yellow or orange lobsters, estimated to occur in about one in 30 million individuals. These colors emerge when a genetic issue causes a reduction in the production of crustacyanin, allowing the red/orange astaxanthin pigment to dominate the shell color even before cooking.
Even more extraordinary are calico lobsters, which have a mottled pattern of orange and black. The split-colored lobster is divided almost perfectly down the middle with two different colors, occurring as rarely as one in 50 million. The rarest of all are albino lobsters, which entirely lack pigment due to a complete absence of color-producing proteins, giving them a translucent or ghost-white appearance with an estimated rarity of one in 100 million.