Ear-shaped pond snail
Radix auricularia
The ear-shaped pond snail is a freshwater pulmonate gastropod with a thin-walled, light brown shell. Its most distinctive feature is the greatly enlarged, ear-shaped aperture that often dwarfs the small spire. It prefers stagnant or slow-moving, nutrient-rich waters with abundant aquatic vegetation and is distributed across Europe and parts of Asia.
Details
Identification
Ear-shaped expanded aperture, very short and pointed spire, shell usually wider than high, tentacles broad and triangular.
Social behavior
Solitary, but often occurs in high population densities when food is abundant.
Diet
Grazes on algal biofilms (periphyton) from surfaces, also consumes detritus and soft plant parts.
Hunting strategy
Grazing on surfaces using the radula (rasping tongue).
Spawning substrate
Aquatic plants, stones, wood, or other solid underwater surfaces.
Overwintering
Overwinters in the sediment or at deeper, frost-free locations of the water body floor.
Ecology
Ecological role
Important primary consumer and decomposer; contributes to the control of algal growth and nutrient cycling.
Natural predators
Fish (e.g., tench, carp), waterfowl, predatory insect larvae (diving beetles), leeches.
Competitor species
Other pond snail species (e.g., Lymnaea stagnalis) and various ramshorn snails.
Ecosystem service
Regulation of algal populations and decomposition of organic waste materials in the water.
Threats
Water pollution by pesticides, habitat loss due to bank stabilization, and drying up of small water bodies.
Scientific profile
Profile
Distinguishing features
The shell is dextral, thin-walled, and horn-colored. The most important feature is the extremely enlarged, ear-shaped aperture, which is significantly higher than the rest of the spire. The spire itself is very small, pointed, and sharply set off from the last, globose whorl. The columellar margin is distinctly reflected, often forming a narrow umbilical chink.
Diet
Mainly periphyton (aufwuchs), consisting of diatoms, green algae, cyanobacteria, and detritus. Occasionally, soft parts of living macrophytes are consumed.
Reproduction
Hermaphrodite with usually reciprocal fertilization. Egg-laying occurs in gelatinous, elongated, slightly curved capsules (egg masses) attached to aquatic plants or stones. Self-fertilization is possible but less common.
Role in food web
Important primary consumer that makes plant biomass and detritus available for higher trophic levels. It serves as an intermediate host for various trematodes (flukes).
Protection & threats
Main threats
Loss of natural shore structures due to engineering, drainage of small water bodies, and excessive eutrophication leading to oxygen depletion in the sediment.
Conservation measures
Preservation and restoration of near-natural shallow water zones and riparian vegetation; avoidance of pesticide input into water bodies.