Life Cycle
P. deltoides is an edible bivalve mollusc primarily found from the Eyre Peninsula to Kingston in South Australia and from Tasmania to Fraser Island in Queensland, with Younghusband Peninsula (Coorong Beach) in South Australian the site of the largest stock abundance in Australia where cockles make up 85% of the total biomass. The Sir Richard Peninsula (Goolwa Beach) and Younghusband Peninsula sand dunes are composed mainly of cockle shell sediments that have formed over the last 6,600 years.
P. deltoides cockles live on high-energy beaches, the juveniles in the intertidal and the adults in the subtidal zone. The cockles use a strong foot to bury into the sand to an average depth of 100 mm and feed by filtering phytoplankton from the water. Cockles mature at around one year of age and live from four to five years reaching a maximum size of 80 mm. They are dioecious serial broadcast spawners with spawning taking place over a long period of time peaking in the spring. Larvae drift as plankton for four to eight weeks in the coastal currents, often travelling large distances. Cockles need heavy surf to live as the surf concentrates the phytoplankton they feed on and increases the oxygen in the water. After periods of calm weather cockles begin to die off.
Read more about this topic: Plebidonax Deltoides
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