- Theodoxus (Theodoxus) fluviatilis fluviatilis (Linnaeus 1758) River Nerite
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© Dr Roy Anderson
© Dr Roy Anderson
Map hosted by the
National Biodiversity Data Centre, Waterford
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A small, solid shell mottled yellow or whitish on green. Has a large body whorl and large aperture closed by an operculum. Lives in hard water of lakes, canals and rivers, usually on stones or other solid support.
Key characteristics
- A solid, dark green shell marbled and spotted with yellow or white.
- Body whorl massive with 1-2 apical whorls perched on top.
- Mouth wide, flattened, with a conspicuous broad white flange round the periphery to aid adhesion.
- Operculum yellowish horn colour, thin but strong, translucent.
Size
9-13 mm
World Distribution
Ranges across Europe from the Pyrenees and Italy to coastal Finland and eastwards to the Caucasus. Distribution type: European Wide Temperate (63).
Irish Distribution
Widely distributed in central Ireland in slow-moving water or on lakeshores. It is recorded as far north-west as Glenade Lough, Sligo but is not in the Erne or Lough Neagh catchments (Kerney, 1968).
Ecology
- Confined to well-oxygenated, usually flowing, water over calcareous bedrock
- Also occasionally on exposed lake shores in the west
- Prefers to settle and feed on rocks. walls or other solid support
Red List status
- Least concern (lc).