SINDERMANN: INTERNAL DEFENSES OF CRUSTACEA 



One of the most severe, widespread, and long- 

 continuing epizootics known in invertebi'ates has 

 affected and still affects European crayfish. It 

 is caused by the fungus Aphanomyces astaci (al- 

 though other microorganisms have been var- 

 iously associated with mortalities). Known as 

 "Krebspest," the disease swept through cray- 

 fish populations of Europe beginning about the 

 turn of the century (Schikora, 1906, 1926; 

 Schaperclaus, 1935; Nybelin, 1935; Mannsfield, 

 1942; Unestam, 1965; Gordon, 1966). Appar- 

 ently resistance differs among species — the 

 American craj'tishes, for example, seem less seri- 

 ously affected by the pathogen in experimental 

 studies. 



Other fungus diseases of Crustacea include 

 a systemic infection of pea crabs. Pinnotheres, 

 from English sea mussels by Leptolegnia marina 

 (Atkins, 1929, 1954a); a systemic disease of 

 cultured prawns, Palaemon serrahis, in England, 

 caused by Pythium sp. (Anderson and Conroy, 

 1968) ; a gill infection of pandalid shrimp, 

 Dichelopandalus leptocenis, from the western 

 North Atlantic, caused by a chytrid-like micro- 

 organism (Uzmann and Haynes, 1969) ; and gill 

 infections of lobsters, Homarus vulgaris and 

 Palinurus vulgaris, in Italy, caused by Ramularia 

 hranchialis and Didymaria palinuri — both Fungi 

 Imperfecti (Sordi, 1958). 



Fungi also infect and destroy egg masses of 

 Crustacea. Eggs of blue crabs, Callinectes sa~ 

 pidiis, from Chesapeake Bay may be infected by 

 Lageiiidiuin callinectes (Couch, 1942; Newcombe 

 and Rogers, 1947; Rogers-Talbert, 1948) ; and 

 eggs of pea crabs are often infected by Plec- 

 tospira dubia and Pythium thalassium (Atkins, 

 1954b, 1955). 



Among the many protozoan diseases of Crus- 

 tacea, those caused by microsporidans are prob- 

 ably the most destructive. Nosema sp. and 

 Plistophora cargoi destroy body muscles of blue 

 crabs (Sprague, 1965, 1966); Nosema pulvis 

 and Thelohania maenadis infect muscles of green 

 crabs, Carcinus maenas (Perez, 1905a, 1905b, 

 1907). Other microsporidan infections of body 

 muscles in Crustacea include those produced in 

 Gammurus by Theileria sp. and Nosema sp. 

 Necrotic muscle fibers containing microsporidan 

 spores were destroyed by phagocytes (Pixell- 



Goodrich, 1928). Other pathological effects of 

 microsporidans on gammarids have been recent- 

 ly reported by Bulnheim (1967) and Bulnheim 

 and Vavra (1968). Crayfish muscles are at- 

 tacked by Microsporida of the genera Thelohania 

 and Nosema (Sprague, 1950b; Pixell-Goodrich, 

 1956; Sogandares-Bernal, 1962). Microsporida 

 are also significant pathogens of shrimps. 

 Sprague (1950a), Woodburn et al. (1957), Iver- 

 sen and Manning (1959) , Iversen and Van Meter 

 (1964), and others have described infections of 

 body muscles and gonads of shrimps from the 

 Gulf of Mexico and European waters, caused 

 by a number of representatives of the genera 

 Thelohania and Nose7na. 



Other protozoan diseases of crustaceans in- 

 clude those caused by ciliates, an ameba, and 

 gregarines. A ciliate, Anophrys sarcophaga, 

 causes a fatal disease in shore crabs, Carcinus 

 maenas, of Europe. The disease, and host re- 

 sponses to infection, will be considered in detail 

 in a later section. Other parasitic ciliates occur 

 in the hemolymph of Crustacea. Paradinium sp. 

 and Syndinium sp. occur in calanoid copepods. 

 Syndinium causes gonad destruction, while Par- 

 adinium colors the host a deep red (Gordon, 

 1966) . Hematodinium sp. has also been reported 

 by Gordon in Carcinus. A suctorian, Ephelota 

 gemmipara, can seriously reduce production of 

 lobster larvae (Dannevig, 1928, 1939). An 

 ameboid parasite, Paramoeba perniciosa, causes 

 a fatal disease (called "gray crab disease") in 

 blue crabs from the Atlantic coast of the United 

 States (Sprague and Beckett, 1966, 1968; 

 Sprague, Beckett, and Sawyer, 1969; Sawyer, 

 1969). Hemolymph of infected crabs becomes 

 cloudy and often incoagulable; in some individu- 

 als most of the cells in the hemolymph are amebae 

 (Sawyer, Cox, and Higginbottom, 1970). A 

 great number of gregarines occur in Crustacea 

 of all kinds, but their pathogenicity seems slight, 

 except for some destruction of the digestive 

 epithelium resulting from heavy infections (Ball. 

 1938; Theodorides, 1961, 1962; Tuzet and 

 Ormieres, 1961; Kruse, 1959a, 1959b). 



Helminth diseases of crustaceans seem less 

 abundant and less severe in their effects than 

 those of microbial etiology. Trematode metacer* 

 cariae encyst in muscles and hepatopancreas of 



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