The Valvatidae are a family of small aquatic prosobranch snails, characterized by a multispiral operculum, and an animal with a pallial tentacle and a protrusible bipectinate gill.
Valvata species from the North American Great Lakes region.
Valvata tricarinata, from Michigan, is shown here and below. This is a common freshwater snail species in the northern and northeastern United States. Members of this genus (and family) are pecular because of their pallial tentacle (the second, posterior tentacle) and bipectinate protrusible gill. This freshwater genus is also distinguished by its multispiral operculum.
Note the multispiral operculum and the pallial tentacle (the more posteriorly located tentacle).
Note the pallial tentacle, the gill (barely visible under the pallial tentacle on the snail's left side), and the eyes.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature