Duck Mussel - Anodonta anatina

    Description

    One of the largest of our freshwater bivalves, typically 75mm but up to 120mm in length. It has a thin shell and is generally slim when closed. Brown and yellow in colour. The hinge margin is notably angled from the mid-axis.

    Similar Species

    The Swan Mussel, Anadonta cygnea, is larger and the hinge margin is parallel to the mid-axis.

    The two can also be distinguished by looking at the posterior (pointed end) adductor muscle scar. In the Swan Mussel, the scar is joined to the pedal retractor scar by a narrow isthmus, whereas in the Duck Mussel these two scars are completely merged.

    Swan_Duck_Mussels.jpg

    Identification difficulty
    ID guidance
    • large: 75-120mm
    • hinge margin angled from the mid-axis
    • differential shell thickening on posterior, giving crimped appearance at posterior
    Habitat

    Diverse. Small streams to large rivers, lakes, ponds and canals.

    When to see it

    All year

    UK Status

    Common and widespread in England, less so in Wales and Scotland.

    VC55 Status

    Common.

    Leicestershire & Rutland Map

    UK Map