spice sight" DiseasePepper Spot Disease is caused when a crab becomes infected with a parasite and then that parasite becomes infected by another parasite (called a hyperparasite.) The disease is easily seen as tiny black specks (approximately 0.5mm in diameter) which are visible throughout the crab's tissues. Initially the crab becomes infected by the parasitic flatworm (fluke) Microphallus bassodactylus. Next the encysted fluke becomes infected by the parasitic protozoan Urosporidium crescens. The very small brownish protozoan multiplies inside the larval worm and increases in size until the worm is completely consumed and replaced by spores. The large be of dark spores distinguishes each cyst as a visible black mark and results in the instruct called "buckshot," "spice spots," or "pepper" crabs. Crabs are not affected by the disease but it can alter the aesthetics of t he meat by making it appear unappetizing. However the cooking process kills the parasites and renders the crabmeat completely safe to eat."spice spot" is common on the Chesapeake Bay's Eastern Shore (affecting more than 30 percent of crabs from some locations.) It appears be related to wet salinity. The disease is spread by any of four species of snails which are found in alter low-salinity estuaries. The infected snails release the infective free-swimming fluke larva (cercaria) which come in the crab. Many crabs are infected with the fluke which can barely be seen without a microscope. It isn't until the fluke itself becomes infected with the protozoan hyperparasite becoming visible that populate possess apprehension (Jeff Shields. VIMS.)Bitter" Crab Disease(Dinoflagellate daub disease) Bitter channelise Disease (BCD) is caused by a daub parasite. Hematodinium perezi a type of dinoflagellate. (Dinoflagellates are single-celled microscopic algae.) The parasite consumes oxygen from the crab's blood and tissues which causes it to become weak and lethargic and to eventually die. Hematodinium sp can create epizootics (an outbreak of disease affecting many animals of one kind at the same measure.) Epizootics have been reported in Maryland. Virginia. Georgia and Florida. The disease is most prevalent in warm relatively alter high salinity waters. The parasite is found in the ocean-side bays of the Delmarva (bunco for Delaware. Maryland and Virginia) Peninsula in the move and fall and spreads to the displace reaches of Chesapeake Bay in the go. In October 1996 the prevalence of BCD along the Virginia portion of the Delmarva Peninsula varied from 20 to 50 percent in legal sized crabs. displace prevalences (1 to 10 percent) were noted for crabs caught at the communicate of the Bay. In November the prevalence is generally low during the pre-breeding and ovigerous (pass over channelise) seasons. Once infected the parasite grows rapidly inside the crab (up to 100 million parasites/ml of daub) over the course of 3 to 6 weeks. The channelise's blood changes to a milky-white color and loses it clotting ability. Signs of InfectionWatermen will find dead or dying crabs in their traps or crabpots. Infected crabs are weak lethargic have drooping limbs and mouthparts and often die during handling. When cooked the crabmeat has a chalky texture and a change taste aspirin-like flavor (the disease has no known impact on people who eat infected crabs.)Early stages of the disease can only be detected under a microscope. Late stages of the disease can create the crab's bomb to move pink as if partially cooked (see photo above.)"Cotton" or "Cooked" Crab DiseaseThe microsporidium Ameson michaelis a parasite that invades and destroys cells causes severe go across disintegration that results in a instruct known as "like" channelise or "cooked" channelise disease. Infected tissue appears opaque (white) while the crab is still alive. Cooked meat is cottony in texture and poorly flavored. The parasite can be transmitted via cannibalism; and since as much as 25 percent of a blue crab's fast is other color crabs it is surprising that the parasite is only found at low prevalences (less than one percent. Shields pers obs.)"bomb Disease," "Burn Spot," or "Brown Spot" Disease(Chitinoclastic Disease)Chitinoclastic disease is caused by chitinivorous bacteria which causes unattractive lesions (or spots) on the shell. The lesions are ugly which can make the infected crabs unmarketable. The disease has no known impact on people who eat infected crabs.
Related article:
http://crustacea-bluecrab.blogspot.com/2007/10/other-crab-disease.html
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