Anadara trapezia Click to enlarge image
Sydney Cockle, Anadara trapezia Image: Dr Isobel Bennett
© Australian Museum

Fast Facts

  • Classification
    Species
    trapezia
    Genus
    Anadara
    Family
    Arcidae
    Order
    Arcoida
    Class
    Bivalvia
    Phylum
    Mollusca
    Kingdom
    Animalia
  • Size Range
    7 cm

The Sydney Cockle is a large cockle (about 7 cm) and quite conspicuous around Sydney's beaches and estuaries.

Identification

The Sydney Cockle shell is creamy white with about 28 deep, predominant ridges along the surface. This cockle is popularly harvested for food in estuarine tidal flats and seagrass beds.

Habitat

Sydney Cockle lives in intertidal mangroves and seagrass.

Distribution

The Sydney Cockle is found in Southern Queensland, New South Wales and Victoria.

Feeding and diet

Like all bivalves, the Sydney Cockle is a filter feeder, taking in the surrounding water and extracting small particles of food. It is very efficient at this and can filter 1.5 litres of water in an hour. In polluted waters, it will also extract metals such as copper and cadmium and retain these in its flesh. Because of this, the species is sometimes used as a bioindicator to determine water pollution levels.

Other behaviours and adaptations

The Sydney Cockle is one of the few molluscs with red blood like us. Most molluscs species have colourless or blue blood.