Flat periwinkle

Flat Periwinkle

Flat Periwinkle ©Alex Mustard/2020VISION

Flat periwinkle

Scientific name: Littorina obtusata
These little sea snails are found amongst the seaweed on rocky shores around much of the UK. They come in lots of different colours, from bright yellow to chequered brown!

Species information


Height: Up to 1.5cm

Conservation status


When to see

January to December


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.

How to identify

The Flat periwinkle has a flattened whorled shell, which is variable in colour but often bright yellow, orange or green. It is distinguished from similar, snail-like periwinkles and topshells by the flattened shape and shiny, smooth shell.


Found on rocky shores all around our coasts, but absent from most of Lincolnshire and East Anglia.

Did you know?

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.

How people can help

When rockpooling, be careful to leave everything as you found it - replace any rocks you turn over, put back any crabs or fish and ensure not to scrape anything off its rocky home.