Meeting Abstract
Many marine organisms live in close association with members of other species. These relationships range from parasitism to commensalism to mutualism. Gastropods in the genus Calliostoma use their feet to wipe the surfaces of their shells, which may influence the settlement and sustained attachment of fouling organisms. Surprisingly, individuals of Calliostoma ligatum living in the San Juan Islands, Washington, are frequently fouled by one to several individuals of the sedentary, suspension-feeding gastropod Crepidula adunca, while individuals of other local species within the genus and other co-occurring trochids, including Margarites pupillus, are rarely fouled. Videos show that the foot of the host passes directly over the epibionts as it wipes the shell without disturbing even very small (< 2 mm) individuals. The majority of epibionts occur on the left side of the body whorl of the host, with the second-most common location in the middle of the posterior portion of the body whorl. Videos of individual Calliostoma ligatum in a recirculating flow tank show that regardless of orientation with respect to flow, water moves up the downstream side of the turban-shaped shell. Thus the preferred locations of the epibionts are regions that would receive enhanced flow. Photographic surveys of marked hosts in the laboratory indicate that although larger (> 5 mm long) individuals of Crepidula adunca do not move, smaller individuals may change their positions on the host or move from one host to another. These observations indicate that this association benefits the epibiont but do not suggest any potential benefits to the host.
