5. Parasites and commensals

Abstract

In and on Oligochaetes all kinds of symbiontic organisms can be found, such as nematodes, ciliates, fungi, rotifers, bacteria, or are used as an intermediate host (tapeworms). This chapter discusses some organisms which are commonly encountered when studying oligochaetes. The tapeworm (Cestoda) of the genus Caryophyllaeus is a very large worm in comparison to the oligochaete itself. The tapeworm is large and thick with a widened head. Caryophyllaeus is a common parasite of carp, bream and other Cyprinids and use mostly tubificids as intermediate host. As the genital area is also thickened due to the presence of this worm it looks as if the worm is mature. Several species of the tapeworm Archigetes, however, mature sexually while in the oligochaete host. Some other species are also parasitic of many fish species and use the oligochaete as intermediate host, this is the case in Cestoda.Keywords: Caryophyllaeus; Cestoda; commensal; oligochaetes; parasite