Valvata

Valvata is a genus of small freshwater snails in the family Valvatidae, a group of aquatic gastropods that possess an operculum. Members occur across the Northern Hemisphere, with many species in Europe and North America. They inhabit streams, rivers, lakes, and springs, often favoring clean, well-oxygenated water and substrates such as gravel, vegetation, or detrital accumulations.

The shells are typically small, usually only a few millimeters to under a centimeter in length. They are often oval or slightly elongate with a low spire, and the surface may be smooth or faintly ribbed. The aperture is rounded and the outer lip is simple. The animals have a broad foot and use their gill for respiration.

Ecology and biology: Valvata snails graze on algae, biofilms, and detritus on submerged surfaces and contribute to the aquatic detrital web. They reproduce sexually, with individuals producing eggs in gelatinous capsules or masses attached to vegetation or substrate. In many species, development is direct, with juveniles hatching as small adults.

Taxonomy and conservation: The genus includes several described species, such as Valvata piscinalis, and numerous others across Europe, North America, and parts of Asia. Some Valvata species are considered rare or locally threatened due to wetland loss, pollution, and changes in hydrology. The genus has a long fossil record and is used in studies of freshwater mollusk diversity and environmental history.