There are actually two species of flat periwinkle but we can’t identify them without dissecting them. When recording the flat periwinkle as part of a recording scheme it is important to record them as Littorina obtusata/fabalis . And make sure to include clear photos to help verifiers confirm your sighting.

Behaviour

Found amongst the seaweeds on which it feeds, the flat periwinkle lives on the lower parts of the shore. It is most commonly associated with Bladder Wrack seaweed and can be mistaken for the air bladders that makes the seaweed float.

They come in lots of different colours, including orange, bright yellow, banded brown and a sort of olive green that makes them hard to spot amongst their seaweed home.

Size

Height: Up to 1.5cm

Status

Common

Distribution

Found on rocky shores all around our coasts

When to see

January to December

Facts

Periwinkles are able seal themselves into their shell by closing the ‘door’ – a round operculum. Flat periwinkles can breed throughout the year and have both male and female forms. Eggs are internally fertilised and laid on seaweed in masses of up to 280 eggs.