Infestation of the clam Venus verrucosa by Sipunculoidea and the lithophagus bivalve, Gastrochaena dubia

Abstract

         From August 2003 to July 2004, specimens of the bivalve Venus verrucosa (L.) were collectedmonthly in the channel connecting the lagoon of Bizerte (Tunisia) to the Mediterranean Sea. During the winter, 4% of the specimens had tiny perforations on the outer and inner faces of the valves; the perforations were connected to an intra-valve network of galleries, caused by 10-12 mm Sipunculoidea. Of specimens collected in February-March, 4% were infested with the lithophagous bivalve, Gastrochaena dubia, that lived within a cavity in the V. verrucosa valves. The cavity communicated to the outside through a calcareous tube developed by the G. dubia near the exit ofthe V. verrucosa siphons, indicating parasitism that can cause progressive perforation of the valveand lead to the death of the host.