Here we broadly review the diet, habitat, and reproduction of the fresh-water gastropods, starting with general observations on their feeding mechanism. Snails are able to exert more control over their immediate environment and the materials entering their mouths than bivalves, and hence there is greater opportunity for ecological specialization. The diets and habitats of 13 freshwater gastropod families are discussed separately, compared and contrasted. Members of the eight prosobranch families tend to grow more slowly than those of the five pulmonate families, and to be found more commonly in lotic environments. Substrate preferences are striking and widespread. Among the groups we catalogue special adaptations and dietary preferences for suspended particles, detritus, bacteria, algal filaments, diatoms, macrophytes, and even carrion. Differential gastropod grazing has been demonstrated to impact algal and macrophyte community structure, as well as the macroinvertebrate community as a whole. Yet against the numerous striking examples of ecological specialization in freshwater gastropods, there is a general uniformity of body plan and habit that suggests the potential for interspecific, as well as intraspecific competition.

We will review a large literature on the complexities of pulmonate reproduction. Adults are generally simultaneous hermaphrodites, although they cannot mate reciprocally at the same time, a situation that may lead to mating conflicts of at least two sorts. Pulmonates can also self-fertilize, although usually at a sacrifice of fitness to both parent and offspring.