These snails are common in the North Temperate to Arctic Zones and throughout the Americas, in readily accessible habitats such as ditches, ponds, lakes, small streams, and rivers.

The family has been recognized since the 19th century, and yet there has been no classification in which relationships between genera are clarified, no agreement on what characters are primitive or advanced, and no consistent ranking.

Physidae has 23 genera, 17 occur in Pacific drainages of North and Central America, eight of these restricted to the region.

The shells of Physidae species have a long and large aperture, a pointed spire, and no operculum.

Burt Vaughan of Washington State University indicates several studies in M. J. West-Eberhardt's recent compendium of research, "Developmental Plasticity & Evolution" (Oxford Press, 2003, pp. 307–362).

Snails exposed to crayfish only showed narrow-apertured, thin elongate shells, with barricading teeth.

The leech-avoidance reaction carries the action one step further: on contact with a leech the snail twists its shell violently and detaches its foot from the substratum as well.

The highest percentage of reactions in Physa were obtained with the two species of leeches that feed chiefly on snails.

Aplexini Amecanautini Austrinautini Stenophysini Haitiini Physini Physellini Physid snails are often introduced to an aquarium accidentally as eggs on aquatic plants.