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• Planorbis carinatus O. F. Müller 1774 Keeled ramshorn

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© Dr Roy Anderson

© Dr Roy Anderson

Shell a regular, flat coil with a conspicuous keel near the mid line. Aperture is a broad oval with the keel roughly in the middle. Last whorl about ⅓ total shell width. Easily confused with P. planorbis in the typical form (var. dubia Hartmann) of northern counties. This is flatter on the lower side and the keel is less developed than in typical carinatus. Widespread in large water bodies.

Key characteristics

• A medium-sized brown shell with conspicuous keel near the mid line
• Aperture broadly oval with the adjoining keel roughly in the middle
• Last whorl about ⅓ total shell width
• Varieties with flatter undersides and shallower keels can be confused with P. planorbis

Size

12-15 mm.

World Distribution

Found across Europe from Spain to Scandinavia. Distribution type: European Wide-temperate range (63).

GBIF distribution map [open in new tab]

Irish Distribution

Essentially a hard water species and often found abundantly in larger water bodies such as the open water of canals, rivers and lakes. Widespread and common in the central plain and the Lough Neagh and Erne Basins but rarer towards west and north coasts.

Ecology

• Common in larger lakes and rivers
• Not in very soft or acid waters, except locally, as in interdrumlin lake margins in Cos Down and Armagh

Red List status

• Least concern (lc).

Wikipedia link

Wikipedia page for Planorbis carinatus