Great Ramshorn Snail
Planorbarius corneus
The Great Ramshorn Snail is the largest native planorbid snail in Central Europe. Its shell is disk-shaped and resembles a ram's horn or a post horn. A unique feature is its red blood containing hemoglobin, which allows it to survive in oxygen-poor environments. It breathes using both a lung and an accessory gill.
Details
Identification
Disk-shaped, sinistral (left-handed) shell; whorls increase evenly in size; body color usually dark brown to reddish.
Social behavior
Solitary, but does not exhibit strong territorial behavior and often appears in groups at feeding sites.
Diet
Primarily feeds on algae biofilm, detritus (decaying organic matter), and dead plant parts.
Hunting strategy
Passive grazing of surfaces using the radula.
Spawning substrate
Undersides of aquatic plant leaves, stones, or other smooth surfaces.
Overwintering
Overwinters in the mud at the bottom of the water body with a reduced metabolic rate.
Ecology
Ecological role
Important decomposer and scavenger; contributes to the reduction of organic waste and algae.
Natural predators
Waterfowl, fish (e.g., carp, tench), predatory insect larvae, and leeches.
Competitor species
Other freshwater snails such as the Great Pond Snail (Lymnaea stagnalis).
Ecosystem service
Improvement of water quality through the decomposition of dead organic matter.
Threats
Habitat loss through drainage of wetlands and heavy chemical water pollution.
Scientific profile
Profile
Distinguishing features
Large, disk-shaped shell without a keel. Whorls increase regularly in width. Unlike most mollusks, it has red blood (hemoglobin). The shell is usually carried at an angle or almost upright. Anatomically sinistral, but functionally appearing dextral.
Diet
Algal biofilms (periphyton), detritus, decaying plant material, occasionally carrion.
Reproduction
Hermaphroditic, usually cross-fertilization. Eggs are laid in flat, gelatinous, reddish-brown capsules attached to aquatic plants or stones.
Role in food web
Important decomposer and primary consumer; processes organic matter and serves as prey for higher trophic levels.
Protection & threats
Main threats
Destruction of small water bodies, drainage of wetlands, excessive herbicide use, and river engineering/habitat loss.
Conservation measures
Protection and restoration of standing waters and oxbows; preservation of riparian vegetation.