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

if a typical adult specimen.

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

Unless identified by a recognised expert, photographic evidence is required. A photo of the adductor scar is often needed. Note the shell's size. If it is an empty shell, it is advisable to retain this in case further checks are needed.

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

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map

Species profile

Common names
Duck Mussel
Species group:
Slugs & Snails
Kingdom:
Animalia
Order:
Unionoida
Family:
Unionidae
Records on NatureSpot:
21
First record:
30/09/2011 (Nicholls, David)
Last record:
20/01/2024 (Nicholls, David)

Total records by month

% of records within its species group

10km squares with records

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