Great Lakes area freshwater snails. Hydrobiids are small to very minute aquatic prosobranch snails. The family has world-wide distribution, and a great many genera and species.
- 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