The effects of sacculinid parasites on two Jamaican crabs

Abstract

This paper deals with the relationships of two Jamaican crabs with their sacculinid parasites; Geograpsus lividus (Milne-Edwards) infected by Sacculina hartnolli Boschma, and Microphrys bicornutus (Latreille) infected by Sacculina bicuspidata Boschma. The following are the more important features discussed. The level of infection and the incidence of multiple parasitism. The modification of the host by the parasite. The causes of this modification. A number of conclusions were reached. In these two saceulinids multiple parasitism is due mainly to the invasion of the host by several larvae. In some other saceulinids, however, polyembryony is the principal cause. The observed host modifications are similar to those described in previous investigations. They tend to change both male and female hosts into ovigerous females, both as regards morphology and behaviour. The parasite affects its host by interfering with the endocrine system. The modification of the host is of advantage to the parasite. This could explain why the sacculinid has evolved the power to induce these modifications.