Native Oyster

Ostrea edulis

What do they look like?

The oyster is a bivalve, meaning it has two shells hinged together. These shells are oval or pear-shaped and are large. They are rough and grey on the outside but white and smooth on the inside. The two halves (or “valves”) are not identical; the left valve, attached to the substrate, is slightly concave whilst the right is flat and sits inside the left. Concentric growth lines are obviously noticeable on the shells.

Where can I find them in Scotland?

Oysters were once much more common, but trawling has reduced their numbers. They remain widely distributed throughout UK seas but in Scotland they are mainly limited to areas of the southwest coast. Oysters reside on the seabed on hard substrate and are often found in large numbers within shallow waters but can occur down to depths of 80 metres.

Fun Fact
Oysters begin life as males but later become females. They will then turn male again and alternate between being male (producing sperm) and female (producing eggs) over the years. In other words, they are protandrous alternating hermaphrodites.
11cm
Length
5-10 years
Lifespan
Priority Species
Conservation Status
A collection of cream-coloured native oysters scattered upon a rock amongst seaweed
© Caitlin Godfrey
A blue-grey native oyster upon wet sand
© Caitlin Godfrey

Want to find out more about what is being done to restore native oyster reefs in Scotland?

Visit our page about Restoration Forth, a charity helping return native oyster reefs and seagrass meadows to the Firth of Forth.