At a Memorial Day cookout, I joined a small group of friends huddled around the tiny, glowing display of a digital camera. On the screen was an unusual looking lobster on a white background. One half of it was brown and the other half bright red as if someone cooked exactly half of the crustacean.

Personally, I’ve never seen a lobster quite like the one on the camera. As I inspected the image more closely, Matt Mataronas, a lobsterman from Little Compton, Rhode Island and brother of the man who caught the rare variety, explained that in 30 years of being a lobsterman, even his father had only seen one other lobster like it.

Split, two-toned, half-and-half, or bi-colored lobsters are so rare—occurring in one of every 100 million caught—that even scientists are unsure why the two sides of the langoustine don’t match. There are some theories about why some clawed crawlers are both brown and red, and studies to discover more about the mysteries lobster shells are in the works.

“People have wondered about lobster color ever since they were first boiled and they go for a muddy brown color to a bright red,” Michael Tlusty, director of research at the New England Aquarium, tells me.

Most lobster shells are composed of three colors: red, yellow, and blue. Lobsters eat shrimp, algae, and other sea creatures that contain cartenoid pigment, which colors the lobsters’ skin red (If they don’t eat the pigment, they remain white). When the pigment is transferred to a lobster’s shell, proteins bind to it, turning it blue. As more and more pigment-protein complexes start to stack up in the shell, they bend and turn a yellow color, according to Tlusty.

There are also blue lobsters, which produce an overabundance of protein due to a genetic mutation, according to the Mystic Aquarium (http://www.mysticaquarium.org/index.cgi/603), and yellow lobsters, which are different colors because of the stacks of complexes in and beneath the shell. Lobsters that are red lack the protein that makes them blue. And all lobsters, except white ones, turn red when cooked because heat breaks the proteins and frees the red pigment.

Researchers I spoke with think that split lobsters form differently on each side because something happens during development, often resulting in a lobster that is half male and half female. Bob Bayer, the animal and veterinary sciences director at the Lobster Institute through the University of Maine, writes in an email that he’s “seen quite a few of these mixed-colored lobsters. They are all hermaphrodites.”

Last summer, a lobsterman donated a split crustacean to the Mount Desert Oceanarium in Maine. “Something happened to that lobster when it was just a few cells big,” says David Mills, the director of the oceanarium, which includes a lobster hatchery and a lobster museum at its Bar Harbor location.

Tlusty agrees with Mill. He hypothesizes that when the first two cells divide, they might completely split. But “those sorts of things are so rare that that’s why we see them so infrequently,” he says.

Aside from the fact that the anomaly is biologically unusual, lobsters that are two colors might also be uncommon because they don’t survive as long as their brown-colored counterparts. “We could see so few of them because it is harder for them to blend into their surroundings,” says Tlusty, making them more obvious to predators.

Tlusty’s interest in the color of lobster shells stems from his research on shell disease. He is conducting research to find out how the color of lobster shells might affect rates of the illness. Bacteria consume the shells of lobsters infected with shell disease, a problem that is currently affecting crustaceans off the coast of Rhode Island and parts of Massachusetts. If the disease continues to move up the coast, it could infect Maine lobsters, which account for a large portion of the US lobster industry. With his team, Tlusty is studying lobster shells to determine how they grow, what environmental factors change the color of their shells, and what that might tell scientists about which lobsters are more susceptible to disease.

As an environmental journalist, I realized my luck when I saw one of these rare creatures—even if it was just on a camera. As researchers uncover more information on why lobsters are different colors and what that might mean for their health, crustaceans of unexpected hues will continue to make news and the occasional appearance at cookouts, either on a digital camera or on my dinner plate.

Story by Susan Cosier. This artcile originally appeared in "Plenty" in June 2007.

Copyright Environ Press 2007