SINDERMANN: INTERNAL DEFENSES OF CRLSTACEA 



perimental inoculation of large numbers of bac- 

 teria. Infectious agents are found in large 

 numbers in the circulatory system only in septi- 

 cemia, which occurs only after a growth phase 

 of a virulent pathogen within the host, often 

 within fixed or immobilized phagocytic cells. 

 Rapid increase in pathogen numbers in the cir- 

 culating body fluid is usually a precursor to death 

 and indicates a failure of host defenses. Thus 

 the artificial introduction of large numbers of 

 microorganisms should not be expected to elicit 

 normal responses in an animal. It should also 

 be noted that insusceptibility barriers to infec- 

 tion, operative in the normal animal, may be by- 

 passed by experimental inoculation, resulting in 

 massive infection and death from microorgan- 

 isms not otherwise known as pathogens. A 

 further qualification mentioned by Aarum is that 

 even the simplest experimental manipulation 

 may change phagoc>i;ic abilities, so that the nor- 

 mal phagocytic response of an animal to path- 

 ogens may be far diff"erent from responses elic- 

 ited experimentally. 



nns, multiplies and causes death, was immo- 

 bilized, agglutinated, and lysed in vitro by serum 

 of several other crabs — particularly Maia squi- 

 nado, Eupagurus p7-ideauxii ,andPorhmus puber. 

 Experimental inoculations of ciliates were 

 cleared usually within several hours. It is in- 

 teresting that the parasite, when experimentally 

 introduced in another member of the Portunidae, 

 Portiinus depumtor, multiplied and killed the 

 experimental hosts just as it did in Carchms 

 maenas. Poisson attributed the reactions of 

 crabs to the ciliate to expressions of a natural 

 immunity, eflfected by agglutinating and lytic 

 activity of the hemolymph. 



Other lytic systems of Crustacea have received 

 passing attention. Cantacuzene (1913) found 

 that hemolymph of the hermit crab, Eupagunis 

 prideaKxii, possessed a heat-labile hemolysin, as 

 well as precipitating and agglutinating activities. 

 Cantacuzene (1921, 1923b) stated that injection 

 of the spider crab, Maia sqninado, with sheep 

 erythrocytes produced hemolysins as well as 

 agglutinins. 



Lytic Systems 



A natural hemolysin for sheep erj-throcj'tes 

 in the hemolymph of West Indian spiny lobsters 

 was reported by Weinheimer, Evans, Stroud, 

 Acton, and Painter (1969). Low temperatures 

 (0° and 4° C) inhibited lysis, which was best 

 demonstrated at 25° and 37° C. Heating the 

 lobster hemolymph to 52° C destroyed lytic ac- 

 tivity. The hemolysin could be adsorbed on red 

 cells or cell stroma at low temperatures. Red 

 cells with the adsorbed lysin were lysed when 

 the temperature was raised to 37° C, which in- 

 dicated a possible enzymatic type of activity of 

 this hemolytic system. The authors suggested 

 a multiple step system, analogous to mammalian 

 hemoljlic systems, consisting of a single protein 

 species which is first adsorbed on the surface 

 of the sheep erythrocyte, and then — in one or 

 more steps — lyses the cell. 



A detailed study of the presence or absence 

 of natui-al immunity to invasion of the hemo- 

 lymph of crabs by a parasitic ciliate, Anophrys 

 sarcophaga, was reported by Poisson (1930). 

 The ciliate, which in shore crabs, Cavciniis viae- 



Agglutinating Systems 



Natural hemagglutinins of the Australian 

 freshwater crayfish, Parachaeraps bwarinatus, 

 were examined by McKay, Jenkins, and Rowley 

 (1969) . Absorptions of hemolymph by erythro- 

 cytes of four mammalian and one avian species 

 disclosed specificity, in that absorption by cells 

 of one species still left agglutinins for cells of 

 other species. The crayfish hemagglutinins were 

 nondialysable and were inactivated at 57° C. 

 In vitro studies with crayfish phagocytes and 

 mouse erythrocytes disclosed that the crayfish 

 hemagglutinins greatly enhanced the adhesion 

 of the erythrocytes to the phagocytes — a specific 

 opsonic effect. A similar effect was observed in 

 vivo, apparently as a prelude to phagocytosis. 



The recent studies support earlier reports of 

 specific hemagglutinins in a number of inverte- 

 brate phyla (Tyler and Metz, 1945; Tyler, 1946; 

 Sindermann and Mairs, 1959; Gushing, Cala- 

 price, and Trump, 1963; Tripp, 1966) with spe- 

 cificities somewhat comparable to those of verte- 

 brate natural isohemagglutinins and with some 

 biological propei'ties (such as enhancement of 



467 



