Microstructure of Scallop and Oyster Shells Infested with Boring Polydora

The microstructure of the shells of scallops Patinopecten yessoensis and oysters Crass-ostrea gigas that were infested with four species of boring polychaetes, namely Polydora variegata, P. websteri, P. convexa, and P. concharum, was studied. Scanning electron microscopy revealed many characteristic concentric-like holes on the entire surface of the burrows of all four species of Polydora. The lateral side of the burrow was heavily scratched horizontally to the direction of the burrow. These characteristics were observed on the interior surface of the burrows which were present in both the foliated structure and the myostracum of scallop shells and in the foliated structure of oyster shells. Foliated crystals had a tendency to rotate at random to the right or the left on the inner surface of the soft body side of the scallop shell. When the sites of penetration by Polydora corresponded to the region where the adductor muscle was attached, characteristic modifications were observed around the canal structure.