By Andrew Goode, University of Maine
It seems every month the newspapers report on a lobsterman hauling a blue, yellow, even orange lobster in the traps. The contrast with a Maine lobster’s normally muted green color catches everyone’s attention. We wondered what causes a lobster to come to be so colorful so we asked Andrew Goode, a researcher at the University of Maine Darling Center who grew up lobstering with his father, to explain the phenomenon.
Albino Lobster, Courtesy of Pen Bay Pilot.
When you look at a lobster, the colors you see are a combination of yellow, blue, and red pigments that bind to proteins within three layers of the lobster’s body. Two layers lie within the shell and the third is in the lobster’s tissue just beneath the shell.
The primary pigment, astaxanthin, is found in the lobster’s natural diet. It gets stored within the skin, beneath the shell, and gives the lobster its classic red, cooked, color. But when the red pigment gets twisted and kinked up by other proteins in the lower layer of the lobster’s shell, the blue pigment, crustacyanin, is produced.
Photo by R. Beauchesne.
In the upper layer of the shell, those proteins will twist astaxanthin to produce pigments with more yellowish hues. The ultimate color of a lobster is determined by the amount of astaxanthin the lobster has consumed and by the lobster’s genetics, which determine the amount of each pigment stored within the shell and tissue.
When cooked, the proteins responsible for producing the blue and yellow pigments cannot withstand the high temperatures and break apart, leaving the red astaxanthin behind.
Funky colored lobsters are mainly caused by genetic mutations that affect the production and storage of these pigments. Let’s say a lobster lacks the ability to make the protein that kinks up astaxanthin. Then the shell appears bright orange/red. Another lobster might produce too much crustacyanin. Then its shell will be blue. And if the lobster can’t store any pigments? It will be an albino.
One of my particular favorites is the “chimera” or split-back lobsters. Each side of the lobster boasts its own colors and occasionally it will have both sets of reproductive machinery. This is because when the eggs are fertilized but not yet extruded, two eggs can come in contact with each other. One egg will absorb the second, producing a lobster with two sets of genetic information and the peculiar ability to store pigments differently on either side of its shell.
Photo Courtesy of UNE.
While it’s common to hear that a specific color mutation is a one-in-a-multiple-million chance, determining exact rarity is difficult. Lobsters can live a long time and produce a lot of eggs. Random mutations in genes can alter colors in different generations. The best information we have on color rarity comes from direct observations from lobstermen. While color mutations are still an uncommon occurrence, the millions of lobsters handled by the fishing fleet annually are likely the reason why we hear so many stories of colored lobsters coming aboard.
If anyone catches an abnormally colored lobster, please contact me, Andrew Goode, at the Darling Marine Center, Andrew.goode@maine.edu.
Photo Courtesy of Grist.
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