SINDERMANN: INTERNAL DEFENSES OF CRUSTACEA 



produced by killed vaccines. Althoug'h the terms 

 "immunity" and "resistance" were used, tlie pre- 

 cise nature of the protection afforded by inocu- 

 lation of vaccines and endotoxin was not de- 

 scribed by the authors. In vitro experiments 

 with hemolymphs of control and resistant cray- 

 fish disclosed no bactericidal or bacteriostatic 

 effects, and McKay and Jenkin suggested that 

 the most important effect of imznunization may 

 have been to increase the metabolic rate of the 

 phagocytes [thereby stimulating phagocytosis]. 



Barker and Bang (1966), extending the ear- 

 lier studies of Cantacuzene (1925b) with the 

 shore crab, Carcinus maenas, and its rhizoceph- 

 alan parasite Sacculina carcini, reported that 

 inoculations of Vibrio sp. caused the hemolymph 

 of the parasite to become incoagulable within 24 

 hr. Masses of gelled material containing bac- 

 teria were seen within body spaces. Septicemia 

 and death, first of the parasite, and then often 

 of the crab host, followed soon after. 



Insuscejitibility factors seem operative when 

 certain parasites of invertebrates fail to develop. 

 Michajlow (1938) and Baer (1944), for in- 

 stance, found that larval cestodes, Triaenophorus 

 and Ligula, penetrated the intestinal wall of a 

 number of copepods, but developed only in cer- 

 tain species. In others, the larvae died and were 

 phagocytized. Hedrick (1935) observed similar 

 differences in survival of larval nematodes. 

 Leger and Duboscq (1908) reported earlier that 

 sporogony of the sporozoan Agregata eberthi 

 (which occurs in the intestinal wall of crabs 

 of the genus Portunus) took place readily in all 

 species except P. puber, in which the parasite 

 was quickly phagocytized after invading the in- 

 testinal wall. 



INTERNAL DEFENSE MECHANISMS 



INVOLVED IN GAFFKAEMIA 



OF LOBSTERS 



The American lobster, Homanis americanus, 

 has an effective internal defense system, consist- 

 ing of active phagocytosis as well as agglutin- 

 ating and bactericidal (or bacteriostatic) activ- 

 ity, against a number of injected bacteria. The 

 protective system seems to fail completely only 



when challenged by Gaffkya homari — which is 

 thus far the only bacterial pathogen known to 

 develop systemic infections in lobsters and to kill 

 them. Probably the most extensive series of 

 reports concerned with responses of inverte- 

 brates to a particular pathogen is that dealing 

 with the lobster (and other decapods) and the 

 highly pathogenic gram-positive micrococcus 

 G. homari. "Gaffkaemia" — the disease caused 

 by G. homari — is enzootic in both the American 

 lobster, Homarus americanus, and the European 

 lobster, H. vulgaris, and has been reported to 

 cause epizootics in captive populations of both 

 species (Roskam, 1957; Goggins and Hurst, 

 1960; Gibson, 1961; Stewart and Rabin, 1970). 

 Microorganisms with characteristics of G. hom- 

 ari have been isolated from shrimp {Penaeus 

 aztecus from the Gulf of Mexico) and from crabs 

 {Carcinus maenas and Libinia emarginata from 

 New England and Cancer irroratus from eastern 

 Canada), but the disease "gaffkaemia" is known 

 only in lobsters. Early descriptions of the di- 

 sease and its etiological agent (Hitchner and 

 Snieszko, 1947; Snieszkoand Taylor, 1947) have 

 been followed during the past decade by studies 

 in several laboratories, which used the lobster 

 and the pathogen as a test system to elucidate 

 responses to infection and other aspects of the 

 host-iiarasite relationship. The possible course 

 of infection in lobsters is summarized in Table 1. 

 Snieszko and Taylor (1947) first satisfied Koch's 

 postulates for the pathogen and demonstrated 

 high mortality following inoculation of cultured 

 G. homari. Stewart and MacDonald (1962) and 

 Stewart et al. (1966) found that 40 to 60% 

 of lobsters they examined from certain locations 

 on the Canadian east coast were infected. 



Studies by Harvey Rabin at Woods Hole and 

 The Johns Hopkins University (Rabin, 1965; 

 Rabin and Hughes, 1968) confirmed that lobsters 

 inoculated with Gaffkya became septicemic with- 

 in 2 days and died a few days later. Inoculation 

 of gram-negative endotoxin 10 hr before ex- 

 posure to the pathogen did not alter the course 

 of infection. Prior inoculation of heat-killed 

 Gaffkya cultures (24 hr before challenge) pro- 

 duced no protection. 



In vitro studies with lobster serum as a cul- 

 ture medium disclosed that Gaffkya growth was 



471 



