''Hematodinium perezi'' is an internal dinoflagellate

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

that infects crustaceans, including

blue crabs Blue crab may refer to: * Blue Crab 11, an American sailboat design * ''Callinectes sapidus'' – Chesapeake or Atlantic blue crab of the West Atlantic, introduced elsewhere * ''Cardisoma guanhumi'' – blue land crab of the West Atlantic * '' Disc ...

, and causes bitter crab disease. Other crustaceans that have been observed to be infected include the Norway Lobster and King Crab, and has been observed to have a significant impact on crustacean fisheries. Infected crabs frequently show signs of weakness and lethargy, and often die due to stress-related handling from fishing as well as metabolic exhaustion due to reduced feeding. This parasite is known to be transmitted between alternate crustacean hosts, through the sharing of water and with the feeding of crabs on infected crabs. ''H. perezi'' is a

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the genus ''Hematodinium'', and perezi has only recently been identified as the specific parasitic dinoflagellate infecting crustaceans. In the east coast of the United States, the disease is most prevalent in the autumn months when the ''H. Perezi'' species blooms off the Mid-Atlantic coast. Infected crabs have been observed to have mortality rates as high as 86 percent after only a few weeks, and infection is found to be more prevalent in higher salinity waters towards the mouth of the bay where ''Callinectes'' go to spawn, generally 12 PSU and up.Messick & Shields, 2000
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Further reading