Physa fontinalis

Physa fontinalis, common name the common bladder snail, is a species of air-breathing freshwater snail, an aquatic gastropod mollusk in the family Physidae. The shells of species in the genus Physa are left-handed or sinistral. The shell is 7 to 12 mm high and 4 to 7 mm wide. The spiral has four to five whorls ( the last of which forms more than three-quarters of the shell height) and the apex is rounded. The shell is very thin-walled, translucent, shiny and is a pale horn colour. The aperture is wide and oval, and the mouth edge is very thin and brittle. The body color is brown to black. The edges of the mantle extend as finger-like lobes over the exterior of the shell. The tentacles are long, slender and cylindrical, with the eyes at the base. The foot is long and thin. Bladder snails are hermaphrodites.