Shell-boring worms on Pacific oyster farms of the U.S. West Coast

This bulletin is based on a series of peer-reviewed journal articles produced by the research team on the WRAC-funded project, “Detection and Control of Mud Blister Worm (Polydora spp.) Infestation on Commercial Oyster Farms Throughout the Pacific Northwest”  

Why the interest in shell-boring worms? 

Shell-boring worms are not harmful to humans or consumers of shellfish, but they can be unsightly particularly for the half-shell market. The worms bur-row in from the outside of live bivalve shells or slip into the soft lip of the open valve and burrow inside, excavating a home that they will occupy and fill with mud and worm feces (Figure 1). Shell-boring worms can cause malnutrition by stealing food intended for the shellfish, and the burrowing activity of these worms puts additional stress on its host by causing it to expend energy for additional shell maintenance, since the shellfish will lacquer over the burrow inside of the shell with nacre to wall off the shell-boring worm, instead of putting energy into growing a  bigger shell. In severe infestations, shell-boring worms can kill their shellfish host.