The River Snail (Viviparus viviparus) is a freshwater gastropod commonly found in slow-moving rivers, canals, and lowland lakes across much of Europe, including the British Isles. Its conical shell reaches up to 40 mm in height and breadth, with 5–6 gently rounded whorls. The shell is glossy, typically olive-green to brown, sometimes showing faint spiral bands. Adults possess a robust operculum that seals the aperture when retracted, protecting against predators and drying out.

Location:
Slow-flowing rivers, canals, and lowland lakes across Europe, including the British Isles.

Average Size:
Shell height up to 40 mm (4 cm).

Family:
Viviparidae (River Snails)

Species:
Viviparus viviparus

Ecological Role:
A grazer and filter-feeder, it feeds on algae, organic micro-debris, and plankton. It contributes to nutrient cycling and helps clarify water by removing suspended particles.

Movement and Sensory Features:
Moves using a muscular foot along substrates. Equipped with a gill lined with cilia that create water currents for breathing and feeding. It has two short tentacles with eyes (simple light detectors) and chemoreceptors for sensing its environment.

Reproduction:
Ovoviviparous (viviparous): internal fertilisation and development within the parent. Females give birth to live, fully formed young. This mode of reproduction enhances offspring survival.

Conservation Status:
Populations are stable and the species is widespread.

Collection Date:
Collected in Barton in August 1911.