Magallana gigas (Thunberg, 1793)
Circumarctic to NW. Pacific, to Namibia, to E. Mediterranean. Introduced in Australia, New Zealand, Chile, NW. America. On stones and rocky bottoms, intertidal down to 80m deep. Original taxon: Ostrea gigas.
Synonyms: laperousii, posjetica…
2m deep, on rock, under the Castle cliff, Cassis, Provence, S. France. 50mm.
Super flat edulis-like specimen, from the sheltered bottoms of Ayrolle lagoon, Gruissan, Occitania, S. France. Despite its flat shape, the shell can be identified as gigas by its purple colours, which never appear in edulis. 70mm.
Younger specimen from Port-Leucate, Occitania. 50,5mm.
Original pictures provided by A. Bertrand (FR) – CC BY-NC-SA.
Milano Marittima, Cervia, Emilia-Romagna, NE. Italy. 53mm.
Fano, Puglia, S. Italy. On wreckage. 45-60mm.
« Ostrea gigas: Testa rudi crassa oblonga lamellata; valvula inferiori subrostrata concava, superiori planiori breviori. » – C. P. Thunberg: “Tekning och Beskrifning på en stor Ostronsort ifrån Japan”, Kongliga Vetenskaps Academiens Nya Handlingar series 2, 14(4-6), Stockholm 1793, via BHL.

Atlantic, wild and dwarf: at low tide on the reef, Pointe des Minimes, La Rochelle, Charente-Maritime, W. France. 62mm. Petricola lithophaga (Retzius, 1786) in upper valve.
A young specimen from English Channel: intertidal, Les Ébihens island, Saint-Jacut de la Mer, N. Brittany, NW. France. Size circa 70mm.
Ostrea gigas in Thunberg.
Size up to 27cm (1,3kg, 2019, Les Sables d’Olonne, Vendée, W. France — “Georgette”, 1,44kg, 25cm, 2019, La Guittière, Vendée). The species can live about 35 to 60 years.
Despite its flat and rounded shell, this is not an Ostrea edulis: the purple rays indicate the belonging to the species Magallana gigas. Les Noires, Saint-Malo, N. Brittany. 43mm.

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