Live lobsters typically appear in shades of greenish-brown, though some exhibit a striking blue shell. This unusual coloration is not due to environmental factors or illness, but rather a unique biological process within the lobster’s shell, making these vibrant blue crustaceans a rare sight.
The Science Behind Their Hue
The distinctive blue color of some lobsters originates from a specific interaction between a pigment and a protein within their shells. Lobsters obtain a red carotenoid pigment called astaxanthin through their diet, often from algae and other plants. This astaxanthin is naturally red, similar to the pigment found in carrots or the one that gives flamingos their pink coloration.
In most lobsters, astaxanthin binds with a protein complex known as crustacyanin. This binding alters the astaxanthin molecule, causing it to reflect blue light instead of red, contributing to the typical greenish-brown camouflage of live lobsters. Blue lobsters possess a genetic mutation that leads to an overproduction of the crustacyanin protein. This excess of crustacyanin results in more astaxanthin molecules being bound, intensifying the blue coloration.
How Rare Are Blue Lobsters?
Blue lobsters are an uncommon occurrence. The estimated probability of encountering one is approximately one in two million. This rarity is linked to the genetic mutation causing crustacyanin overproduction.
The blue coloration is a natural genetic variation, not a sign of disease or environmental influence. While the trait can be inherited, it is complex, involving multiple genes. Even if blue lobsters breed, their offspring are not necessarily all blue, and interbreeding with common-colored lobsters dilutes the trait. Their bright color can also make them more conspicuous to predators, potentially shortening their lifespan in the wild.
Beyond Blue: Other Lobster Colors
Beyond the typical greenish-brown and the rare blue, lobsters can display other unusual colors, including orange, yellow, and calico patterns. Some can even be albino, appearing white or translucent due to a complete lack of pigment. These varied colorations are a result of different genetic mutations impacting how astaxanthin is produced, stored, or bound to proteins within the shell.
All lobsters turn bright red when cooked. This transformation occurs because heat breaks down proteins like crustacyanin that bind to astaxanthin. Once released, the astaxanthin pigment reverts to its natural red-orange hue, which is then visible on the cooked lobster’s shell.