Exoskeletons of kinorhynchs in tissues of the bivalve Macoma balthica in the Baltic Sea, southwestern Finland

Exoskeletons of kinorhynchs, resembling those of Echinoderes levanderi Karling, were encountered in tissues (most often in the gonad) of Macoma balthica (L.) taken from muddy bottoms at depths of 20-40 m. They could be found in up to 70% of individuals. The foreign bodies were usually surrounded by clam granulocytes. Resorption of the cuticular parts was difficult; such material was capable of surviving in the tissues for at least a year. In clams taken from a depth of 7-8 m no kinorhynchs were found.