Based upon the results, variations between sexes of P. canaliculata can be due
to differences in the height of the spire and differences in shell opening. The height of
the spire is related to the gastropod’s natural response for survival (Borra, 2006).
Differences in the shape of the shell opening could be attributed to predatory defense
of the snail. The shape of the shell opening or the aperture is the best way to prevent
shell entry as frequently performed by predators such as decapods (DeWitt, 2000).
Narrow apertures are a potentially important defense in freshwater. Conversely, wider
aperture indicates vulnerability to predation (Williams, 2005). It could be inferred that
predators may affect apertural shape of the freshwater snails.
Sexual dimorphism in P. canaliculata has been inferred on size differences
where females are larger than males (Estebenet and Cazzaniga, 1998). In addition to
size dimorphism, qualitative analysis revealed that there appears to be variation in the
shape of the aperture and operculum where females have broader mouth and a
concave operculum and the males a convex operculum (Cowie, 2006). Since the