Research Product

Crustacea serve as hosts to symbiotic, commensal, parasitic, and pathogenic representatives of all major taxa of Protozoa. Studies of microsporidian epizootics in shrimp, crayfish, and other decapod Crustacea, amoebic epizootics in crabs, and ciliate protozoan outbreaks in shrimps and crabs demonstrate the strong periodic and chronic impact of Protozoa. Mortalities ranging from 1 to 100% in natural and captive populations of Crustacea have been linked to protozoan etiologies. As pathogens of Crustacea, Protozoa have been more intensively studied than most viral, bacterial, fungal, or metazoan pathogens. Yet, there are huge gaps in our knowledge concerning life-histories, mechanisms of transmission, and pathogenesis of Protozoa associated diseases of Crustacea, even in the cases of long-known relationships. This review of representative Protozoan-Crustacean relationships emphasized disease-causing Protozoa and the related responses of their specific crustacean hosts. Examples of all major taxa of Protozoa occurring in or on Crustacea are examined. Surveys of Protozoa known to be associated with decapod Crustacea have been done but not for other orders of Crustacea. The predominant use of decapod Crustacea as exemplary hosts reflects the substantial disease research done on this taxon of Crustacea because of their commercial importance.