“We’ve seen a number of color variants in blue crabs at VIMS,” he adds, “but we’ve never seen this particular color morph in an entire crab. MALE BLUE CRAB SKINSays Shields, “This blue crab is most likely an extremely rare genetic mutation that has altered the amount of certain pigments in the shell, the crab’s ability to bind to proteins in the shell, or the number of pigment-producing cells in the skin beneath the shell.” But McInteer’s "true-blue" blue crab appears to be a color variant and not an infection. Shields has also seen a rare orange coloration that is caused by a virus. He has seen this several times in crabs from Chesapeake Bay. VIMS Professor Jeff Shields, an expert in crustacean physiology and disease, says that purple coloration can be caused by a parasite that affects the muscles and shell. Female blue crabs have red tips on their claws. Lipcius says it's rare to find blue crabs that are completely blue - the last one reported to VIMS was in 2009 -but he notes "they have been found previously, as have albino and purple crabs.” In a typical blue crab, only the legs are blue the shell is beige. “The blue color is most likely a genetic abnormality,” says Lipcius, “like in the bilateral gynandromorph.” The latter reference is to a rare crab shared with the Lipcius lab in 2005 - this one split right down the middle, with its right half female and its left half male. Although the crab - a male - has now died, marine scientist Gabby Saluta says researchers will keep the specimen frozen for possible study in the future. Recognizing its rarity, they donated it to the laboratory of Professor Rom Lipcius, an expert in crustacean ecology at William & Mary's Virginia Institute of Marine Science. McInteer, who at 73 has been crabbing commercially for 10 years and recreationally for decades, says he’s caught blue crabs “with blotches of white, and some other slight discolorations, but never a solid-blue blue crab.” “Alan yelled, ‘Come look at this crab!’ He very carefully took him out of the pot and then I could see exactly what it was - I’d read about how they occur every now and then, so we knew what we had.” “We were excited about it,” says McInteer. If you would like your business listed on Beach-net Contact us here!ĭelaware Web Design & Internet Advertising - Coastal Images Inc.Jim McInteer and his crew mate Alan Payne knew they had captured an oddity the moment they pulled their crab pot from the York River last Tuesday. *Information courtesy of the University of Delaware Sea Grant Marine Advisory Service. Once hatched, the zoeae become part of the oceanic plankton and drift for 40 days or more, growing and molting through the megalopa stage to the first crab stage. The orange eggs gradually turn yellow and finally dark brown during the 2-week incubation period. Only 1 out of 1 million eggs will reach adulthood. Two to nine months later (depending on if it's spring or fall), the female will attach 700,000 to 2 million eggs to the swimmerets on the underside of her abdomen. The crabs then assume the doubler position (male carrying female) and might stay like this for 2 to 3 days before and after mating, which lasts 5 1/2 hours.įemales are about 1 1/2 years old at the time and will store the sperm for use in 2 or more spawnings during their 3-year life span.Īfter mating, the female migrates down the tributaries and bays seeking water of higher salinity. Just before the last molt, the female secretes a sex attractant that calms the male's blue claw. Males (blue-tipped claws) may mate any time during the last 3 or 4 molts. Ordinarily, females (red-tipped claws) mate only once, while they are in the soft shell state after the last molt. Order Authentic Maryland Crab Cakes Online!Ĭlick here to visit a new website from the University or Delaware College of Marine Studiesīlue crabs mate in brackish waters between May and October, peaking in late summer.
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