soft-shell clams

  Mya arenaria
Linnaeus, 1758

Relevant Synonyms


 photo: S. Gofas    

Shell large, strong but chalky, inequivalve with lv generally smaller. Outline ovate-elongate; anterior end rounded; posterior slightly pointed. Gapes at both ends. Rough sculpture marked by concentic lines (growth lines). Distinctive hinge with an erect spoon-like tooth (chondrophore) located under the beak in left valve. Pallial sinus deep, reaching to the middle of the shell.

color : chalky white shell with thin greyish/brownish periostracum. Interior of shell brown.

common size : to 152 mm in length, to 60 mm in height.

The large projecting chondrophore in lv distinguishes it from any of the otter shells (Lutraria). Similar to M. truncata Linnaeus, 1758 but bigger and more ovate. M arenaria gapes at both ends whereas M. truncata gapes widely at the posterior and hardly at the anterior edge.

Great adaptability and tolerance to low salinities and pollution. It lives buried as much as 20 cm deep in mud and sand, extending only its long siphon to the water. It rapidly retracts its siphon below the surface, if disturbed, and ejects a stream of water. Experiments on habitat selection and adult-larvae interactions in settling larvae showed that settlement was highest at a sheltered than at an exposed site (Snelgrove et al., 1999).

habitat : muddy, sandy and gravelly bottoms, intertidal from the shore and estuaries mainly in shallow water down to 75 m. Highest densities in muddy sand areas.

1st Mediterranean record
France, 1976 [no collecting date].

Worldwide: North Atlantic Ocean; introduced for mariculture in the Baltic Sea and the Black Sea. Mediterranean: reported first from France, Etang de Berre (Stora, 1976); successively from northern Adriatic and western Sicily (Poutiers, 1987); Greece, Saronikos Gulf (Zenetos et al., 2002).

Abundant locally; now very common in Etang de Berre (Zibrowius, pers. comm.) and some lagoons in the Gulf of Lions (France). Other records such as in Saronikos Gulf are based on one or very few specimens.

speculated reasons for success :
great adaptability. Flume experiments have shown that larvae settle in defaunated sediments typical of their adult environment (Butman et al., 1988).

In Europe the species occurs from Norway to Arcachon, in France; but it is believed to have been extinct in Pleistocene times and reintroduced by man in historical times (Petersen et al., 1992). Introductions to the Mediterranean are definitely due to man and date from the last decades. However, its record in Saronikos Gulf, Aegean Sea, is probably an accidental introduction attributed to shipping as there no shellfish farms in the vicinity.

Edible, harvested in large numbers as food in many locations; also used as bait.


  • Pelorce J., 1995. Un débarquement pacifique sur les côtes du golfe du Lion! Xenophora, 71: 5.
  • Petersen K.S., Rasmussen K.L., Heinemeier J. and Rud N., 1992. Clams before Columbus? Nature, 359: 679.
  • Porcheddu A.S., Francour P., Soltan D., 1999. Considerazioni sul ritrovamento di una populazione di Mya arenaria L., 1758 negli stagni di Berri e di Vaïne (France meridionale). Bolletino malacologico, 34(9-12): 167-171.


  • Snelgrove P.V.R., J. Grant and C.A. Pilditch, 1999. Habitat selection and adult-larvae interactions in settling larvae of soft-shell clam Mya arenaria. Marine Ecology Progress Series, 182: 149-159.
  • Stora G., 1976. Evolution des peuplements benthiques d'un étang marin soumis à un effluent d'eaux douces. Bulletin d'Ecologie, 7(3): 275-285.


Last update : December 2003

©ciesm 2002