Oorzaak van een (gerepareerd) gat in een Zwanenmossel Anodonta cygnea (Linnaeus, 1758) gevonden

In an earlier paper the question was raised how a later repaired 6 x 8 mm hole in a Swan mussel shell was formed. A predator would have continued breaking the shell and consuming the animal. The hole was probably made during cleaning of the ditch, whereby material including some mussels was disposed on the ditch embankment. Mr. Klaas Kikkert (isle of Texel, province of North Holland) wrote me that he had collected mussels still living after ditch cleaning and had returned them to the water. The second author found another example of a damaged Swan mussel on the mainland near Oosterleek (province of North Holland). Apparently Swan mussels are able to repair a hole in the shell caused by ditch cleaning.