MolluscIreland - land and freshwater
  • Bathyomphalus contortus (Linnaeus 1758) Twisted ramshorn
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Bathyomphalus contortus
© Dr Roy Anderson
Bathyomphalus contortus
© Dr Roy Anderson

Map hosted by the National Biodiversity Data Centre, Waterford
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A small, very tightly coiled shell of 7-8 whorls. The whorls overlap on the underside. Color mid brown but invariably coated with a dark brown matt deposit. Aperture flattened and enveloping the previous whorl. Widespread and common.

Key characteristics

  • A small, very tightly coiled flat shell of 7-8 whorls
  • The whorls overlap on the underside producing a shallow umbilicus
  • The aperture is a flat oval and follows the curvature of the previous whorl
  • Shell light brown to olive-brown but invariably coated with a dark brown deposit

Size

4.5-6 mm.

World Distribution

Found across Europe and Siberia to the Far East. Distribution type: Eurasian Wide-temperate (65).

Irish Distribution

Widespread and generally common except in the south-west, extreme west and north-west.

Ecology

  • This snail has a predilection for small, impoverished water-bodies, drains and marshy or peaty pools, also floogplain marshes
  • It occurs only sparingly in larger water-bodies
  • Seemingly tolerant of acidic conditions to a greater extent than other pulmonates except perhaps Radix balthica - often the only species present in drains or pools in and around raised bogs

Red List status

  • Least concern (lc).

Wikipedia link

Wikipedia page for Bathyomphalus contortus

 Anderson, R., (2016). Bathyomphalus contortus (Linnaeus 1758). [In] MolluscIreland.
http://www.habitas.org.uk/molluscireland/species.asp?ID=43 Accessed on 2017-12-15.