Occurrence of the entocommensal rhynchocoelan, Malacobdella grossa, in the oval piddock, Zirfaea crispata, on the Yorkshire coast

Abstract

Various aspects have been studied of the relationship between the entocommensal nemertean Malacobdella grossa [O.F. Müller, 1776] and its host on the Yorkshire coast, the lamellibranch Zirfaea crispata L. Larger host populations clearly show both a higher overall percentage infection and greater numbers of multiple infections. Larger hosts tend to harbour larger Malacobdella; allied with this fact is the conclusion that the older the host population the more restricted is the availability of potential hosts for future infections.