Coevolution of Freshwater Gastropods and Their Predators

We have tried to show that freshwater gastropods (especially those in temporary waters) are generally less well adapted to avoid predation by crushing or other shell destruction than are most benthic marine snails. The sturdiest freshwater snail shells occur in ancient lakes and rivers, but even here such common marine antipredatory characteristics as narrow and dentate apertures are wholly absent. Limitations on calcification may be in part responsible for this greater conservatism of freshwater as compared to marine gastropods, but many architectural types incommensurate with the demands of carbonate conservation are common among freshwater snails. Low temperatures in many freshwater systems may also place severe metabolic limitations on specialized trophic linkages among both molluskan prey and their predators.