GUT STRUCTURE, FEEDING AND DIGESTION IN THE BRANCHIOBDELLID OLIGOCHAETE<i>CAMBARINCOLA MACRODONTA</i>ELLIS 1912, AN ECTOSYMBIOTE OF THE FRESHWATER CRAYFISH<i>PROCAMBARUS CLARKII</i>

Abstract

1. The branchiobdellid Cambarincola macrodonta is an ectosymbiote of the crayfish Procambarus clarkii and feeds by grazing on the microflora and fauna of the host's body surface. It is likely, however, that this type of feeding is supplemented by opportunistic commensalism in which particles of the host's food are captured and ingested. 2. The feeding mechanism is simple, there is little apparent specialization of function in the salivary glands and there are no evident adaptive features in either gut structure or function. 3. Digestion is both intra- and extracellular and is dominated by arylamidases (exopeptidases). 4. The nutritional physiology shows some similarities to that of the Hirudinea, notably in the emphasis on exopeptic digestion, but it is concluded that these reflect convergence rather than taxonomic affinity.