European valve snail
Valvata piscinalis
The European valve snail is a small freshwater prosobranch snail with a globose, right-handed shell. It is uniquely characterized by its feather-like external gill, which is clearly visible protruding from the shell aperture when the animal is active. It possesses a horny operculum (valve) that allows it to seal its shell tightly in response to predators or desiccation. This species typically inhabits stagnant or slow-moving waters with silty substrates and abundant aquatic vegetation.
Details
Identification
Conical shell with 4-5 strongly convex whorls, circular aperture, concentric operculum, filiform tentacles, and an additional feather-like gill.
Social behavior
Solitary, but often occurs in high population densities at suitable feeding sites.
Diet
The diet primarily consists of algal biofilms (periphyton), detritus, and fine organic particles scraped from the substrate.
Hunting strategy
Grazer; uses the radula to scrape off microalgae and organic films.
Spawning substrate
Smooth surfaces of aquatic plants, stones, or more rarely detritus.
Overwintering
Overwintering in the sediment or on deeper plant parts, often in a dormant state.
Ecology
Ecological role
Important primary consumer and decomposer that breaks down organic matter and serves as prey for higher trophic levels.
Natural predators
Fish (e.g., tench, carp), waterfowl, predatory leeches, and insect larvae.
Competitor species
Other small freshwater snails such as Bithynia tentaculata or various ramshorn snails.
Ecosystem service
Regulation of algal growth and support of nutrient cycling through the decomposition of detritus.
Threats
Water pollution, acidification, habitat loss through shore reinforcement, and intensive weed removal.
Scientific profile
Profile
Distinguishing features
The most important feature is the feather-like gill protruding from the aperture and an additional thread-like mantle process on the right side of the body. Unlike many other freshwater snails, it possesses an operculum with concentric construction. The umbilicus is clearly visible and deep.
Diet
Fine detritus, diatoms, green algae, and organic film on substrates.
Reproduction
Simultaneous hermaphrodite; reproduction usually occurs through cross-fertilization. Eggs are deposited in gelatinous capsules (approx. 10-30 eggs per capsule) on aquatic plants or stones.
Role in food web
Important primary consumer and decomposer; serves as a link between primary production/detritus and higher trophic levels.
Protection & threats
Main threats
Destruction of shore habitats, excessive eutrophication, drainage of shallow water zones, and chemical pollution (pesticides).
Conservation measures
Protection and restoration of near-natural shore areas, preservation of macrophyte stands, and reduction of diffuse nutrient inputs.