The dextrally-coiled shells are smooth (except for growth lines conforming to the shape of the outer lip) and are usually rather nondescript.

The shell offers very few robust characteristics to the systematist who is attempting to classify the species within this family.

The shell can sometimes even assume a corkscrew or hornlike shape by loosening of the attachment of body whorl.

The head, foot, mantle and visceral coil are colored pale gray to dark purple-black with melanin pigments.

The species usually have both male and female individuals, but very rarely reproduction may be parthenogenic, caused by internal fertilization.

The females lay eggs in single capsules on the leaves or stems of water plants.

But sometimes they produce eggs that are hatched within the pallial gonoduct of the body, and in these cases the young are born alive.

A few occur in marine environments on sandy or muddy bottoms between algae and sea grass.

[3] Over the years there have been numerous attempts to give an adequate and more finely divided classification.

A study by Wilke et al. (2001)[5] using molecular data from COI (Cytochrome c oxidase subunit I) and 18S genes has resulted in a new tentative set of subfamilies: Hydrobiinae, Pseudamnicolinae, Nymphophilinae, Islamiinae and Horatiinae.