Species encyclopedia

Pacific Oyster

Magallana gigas


The cupped oyster, also known as the Japanese oyster, is originally from the Pacific. It was introduced in France in 1966 to replace the Portuguese oyster, which had been decimated by viruses.

The Portuguese oyster itself had been a replacement for the European flat oyster, which had become scarcer after a series of epidemics.


Oysters are hermaphroditic. They are born male, but change sexes every year. Mating occurs during the summer, when the temperature of the water exceeds 20°C. The clutch of eggs weighs as much as 60% of the weight of the oyster’s body. The adults excrete reproductive cells directly into the water where fertilization then takes place. After metamorphosis, the larvae attach to different supports by secreting a liquid that solidifies when it comes in contact with water.

Oysters live in tidal zones, sometimes in slightly desalinated water. They feed on particles present in the water. For that purpose, they filter 1 to 10 litres of seawater each hour, for each gram of dry flesh. This species can grow to a maximum of 45 cm.

In Ancient Greece, people ate the oysters they collected from natural banks. The top shell was used as a voting ballot to banish someone from the City, giving us the « ostracism » (action of excluding someone from a group) from the Greek ostrakon, meaning "shell".

Atlantic Ocean


Species encyclopedia

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