Description: A very large elongate-oval shell with the upper and lower margins in mature specimens nearly parallel and the hind end drawn out and somewhat narrowed. Umbos beyond the middle, towards the front end. The periostracum is glossy and mainly brown. Found widely in stagnant muddy or silty habitats in larger water bodies. 100-150 mm.

World Distribution: Extends slightly farther north than A. anatina in Europe but but less far south. Distribution type: Eurosiberian Temperate (74).

Irish Distribution: Widely but thinly distributed in the lowlands.

Ecology:

• A species of stagnant muddy or silty habitats in larger water bodies
• It may be seen protruding from the bottom in low water in the summer from fishing stands on lakeshores etc.
• Probably much under-recorded

Key Identification Features:

• A very large elongate-oval, relatively thin, shell
• The upper and lower margins in mature specimens are nearly parallel and the hind end drawn out and somewhat narrowed
• Umbos beyond the middle, towards the front end
• The periostracum is glossy brown, sometimes with shades of green or yellow-green
• Shell is of a fairly even thickness throughout, as seen against a strong light

Red list status:

• Vulnerable (VU).

Distribution Map from NBN: Anodonta cygnea at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Anodonta cygnea at iNaturalist World Species Observations database.

GBIF data for Anodonta cygnea | Classification: Bivalvia, Unionida, Unionidae, Anodonta

Thumbnails for genus Anodonta