Changes in radula and jaw during life stages of Eucobresia diaphana (Draparnaud, 1805) (Gastropoda, Pulmonata, Vitrinidae)

For a better understanding of the changing feeding pattern of Eucobresia diaphana (Draparnaud, 1805) during its life cycle, the radula and jaw of juvenile and adult specimens were studied by using scanning electron microscopy. The feeding pattern was observed during fieldwork and in an experimental setting. The radula and jaw of adult E. diaphana resemble the descriptions and figures given in the literature. The most striking characteristics of the juvenile radulae, apart from the smaller number of teeth and rows and their small size, are (1) the slow development of the central teeth, (2) the varied shape of the laterals and (3) the irregular number of cones and cusps on those laterals. In juvenile specimens, the median projection of the jaw still consists of two parts. After the summer season, the jaw and radula are fully grown. The changes during the maturation are illustrated and discussed. Adult Eucobresia diaphana appear to be omnivorous, whereas juvenile specimens have a more herbivorous feeding pattern. The juvenile teeth may also have a special function during hatching.