White ramshorn snail
Gyraulus albus
The white ramshorn snail is a small, freshwater air-breathing snail with a flatly coiled, whitish to yellowish shell. It reaches a diameter of approximately 4 to 7 millimeters and is characterized by fine spiral lines on its surface. This species prefers stagnant or slow-moving waters with dense aquatic vegetation, where it grazes on leaves and stones. As a hermaphrodite, it deposits its eggs in small, gelatinous capsules on aquatic plants.
Details
Identification
Flat shell with 4-5 whorls; whitish to greyish coloration; very fine, dense spiral lines (reticulate structure); aperture obliquely oval.
Social behavior
Solitary, but often forms loose groups at favorable feeding sites.
Diet
Feeds primarily on algal growth (periphyton), detritus, and decaying plant parts.
Hunting strategy
Grazer, scrapes food using the radula.
Spawning substrate
Undersides of aquatic plant leaves, stones, or deadwood.
Overwintering
Overwinters in the sediment or on dead plant parts in frost-free depths.
Ecology
Ecological role
Important decomposer and consumer of algae; serves as prey for various aquatic predators.
Natural predators
Fish, waterfowl, leeches, and predatory insect larvae (e.g., dragonfly larvae).
Competitor species
Other small ramshorn snails such as Gyraulus crista or Planorbis planorbis.
Ecosystem service
Contribution to water purification by breaking down organic matter and controlling algae.
Threats
Destruction of riparian vegetation, heavy eutrophication, and the use of pesticides.
Scientific profile
Profile
Distinguishing features
The main feature is the fine reticulate structure of the shell surface (spiral lines), visible under magnification. In contrast to Gyraulus acronicus, the last whorl is less strongly expanded and the surface is not smooth. The umbilicus on the underside is wide, revealing all whorls.
Diet
Periphyton (algal growth), detritus, and fine organic particles, occasionally soft plant tissue.
Reproduction
Hermaphroditic; reproduction usually occurs in spring and summer. Eggs are deposited in small, gelatinous, flat capsules on hard substrates or plants.
Role in food web
Primary consumer and important decomposer; serves as a link between primary production (algae) and higher trophic levels.
Protection & threats
Main threats
Loss of macrophyte stands due to eutrophication or mechanical weed control; river engineering and destruction of natural shallow water zones.
Conservation measures
Protection and restoration of shore zones; promotion of aquatic vegetation; reduction of nutrient inputs.