Physella acuta
Physella acuta is a species of small, left-handed or sinistral, air-breathing freshwater snail, an aquatic gastropod mollusk in the family Physidae. Common names include European physa, tadpole snail, bladder snail, and acute bladder snail. In addition, Physa acuta, Physa heterostropha (Say, 1817) and Physa integra (Haldeman, 1841) are synonyms of Physella acuta (Draparnaud, 1805).

Shell description

Snails in the family Physidae have shells that are sinistral, which means that if  the shell is held with the aperture facing the observer and the spire pointing up, then the aperture is on the left-hand side.

The shells of Physella species have a long and large aperture, a pointed spire, and no operculum. The shells are thin and corneous and rather transparent.

Distribution

It was once thought that the indigenous distribution of Physella acuta is Mediterranean. However, when Physella heterostropha is  considered to be a synonym, then the indigenous distribution of the species includes North America.

Physella acuta is a common species which is common in all of North America and Europe. The species seems to have first spread through the Mediterranean regions and then more slowly into Northern Europe.

In Europe 
This species is found in:
 Belgium
 Croatia
 Italy
 Czech Republic - not evaluated (NE)
 Slovakia
 Germany
 Netherlands
 Pripyat River since 1983 and in Neman River basin in Belarus since 2007
 Denmark
 and others

The distribution also includes Mediterranean regions and Africa.

In America 
The distribution includes the United States: Maryland, New Jersey, and Virginia.
 Cuba - native, also with Tarebia granifera it is the most common freshwater snail in Cuba

Ecology

Habitat
This species lives in freshwater rivers, streams, lakes, ponds, and swamps.

Physella acuta is frequently found in anthropogenic reservoirs, occurring in warm water discharges from power stations and in some rivers, but very rarely and not numerously in clay pit ponds. It can survive well under temporary harsh conditions (extreme temperature and water pollution), as long as they are short-lived.

Feeding habits 
These snails eat dead plant and animal matter and various other detritus.

Because Physella acuta forages mainly on epiphytic vegetation and on the macrophytes, whereas other gastropods (Planorbis planorbis, Radix ovata) exploit the algal cover or phytobentos on the bottom, competition between Physella acuta and other gastropods appears to be minimal.

Interspecific relationship 
This species successfully co-exists with other alien gastropods: for example with Potamopyrgus antipodarum in many streams, lakes and ponds in New Zealand and with Lithoglyphus naticoides in the Danube River.