Viviparidae

Viviparidae is a family of freshwater snails in the class Gastropoda, commonly known as river snails or livebearing snails. They occur in freshwater habitats worldwide, especially in slow-moving rivers, lakes, ponds, and wetlands, from temperate to tropical regions. The shells are typically medium to large, elongated to conical, with one or more whorls, and the animal bears an operculum. The morphology varies by genus, but a stout body and a well-developed aperture are common.

Reproduction is a defining feature of the family: viviparid snails give birth to free-living juveniles rather than laying eggs. Brood size ranges by species, but juveniles are usually visible soon after birth.

Ecology: They graze on algae, periphyton, and detritus, contributing to nutrient cycling and serving as prey for fish and other predators. They are typically found in habitats with adequate substrates for grazing and shelter.

Classification and genera: The family includes several genera, notably Viviparus, Bellamya, Cipangopaludina, and Marisa. Species-level diversity is greatest in tropical and subtropical regions, though many species occur in temperate zones as well.

Human relevance: Some species have been introduced outside their native ranges as aquarium or ornamental snails and have become invasive in several areas. Conservation concerns vary by species and location, with habitat destruction, pollution, and competition with invasive snails posing threats to restricted-range taxa.