Great pond snail
Lymnaea stagnalis
The great pond snail is the largest native freshwater snail in Europe, with shells reaching up to 7 centimeters in length. Its shell is right-handed, thin-walled, and features a very sharp, pointed spire. It inhabits stagnant or slow-moving waters with abundant vegetation and is a pulmonate snail that needs to breathe atmospheric air at the surface. The shell color ranges from light brown to almost black, while the body is typically grayish or yellowish.
Details
Identification
Pointed, right-handed shell with 4.5 to 6 whorls; large, flattened, triangular tentacles; shell aperture is tall and oval.
Social behavior
Mainly solitary, but exhibits complex mating behavior as a hermaphrodite and is capable of simple associative learning.
Diet
Omnivorous: Feeds on periphyton (algae), aquatic plants, detritus, carrion, and occasionally small invertebrates such as insect larvae.
Hunting strategy
Grazing: Scrapes food from surfaces using its radula (rasping tongue).
Spawning substrate
Gelatinous egg strings are attached to aquatic plants, stones, or aquarium glass.
Overwintering
Overwintering in the sediment or deeper water zones with a significantly reduced metabolism.
Ecology
Ecological role
Important decomposer in the ecosystem; serves as an intermediate host for trematodes (flukes) and as a food source for predators.
Natural predators
Fish (e.g., tench, carp), waterfowl, ducks, muskrats, predatory insect larvae, and leeches.
Competitor species
Other large freshwater snails such as the great ramshorn snail (Planorbarius corneus).
Ecosystem service
Regulation of algal growth and decomposition of organic material (biomass recycling).
Threats
Eutrophication, destruction of riparian vegetation, use of molluscicides, and the drying up of small water bodies.
Scientific profile
Profile
Distinguishing features
Largest native freshwater snail; the shell aperture is usually taller than the spire; characteristic triangular tentacles (distinguishing it from Physidae which have filiform tentacles); shell is dextral.
Reproduction
Hermaphroditic with cross-fertilization; eggs are laid in gelatinous strings up to 6 cm long on aquatic plants or stones.