Duck Mussel - Anodonta anatina
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.
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.
- large: 75-120mm
- hinge margin angled from the mid-axis
- differential shell thickening on posterior, giving crimped appearance at posterior
Diverse. Small streams to large rivers, lakes, ponds and canals.
Common and widespread in England, less so in Wales and Scotland.
Leicestershire & Rutland Map
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Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015