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. If you want to learn more about our rockpool life, Wildlife Trusts around the UK run rockpool safaris and offer Shoresearch training - teaching you to survey your local rocky shore. The data collected is then used to protect our coasts and seas through better management or through the designation of Marine Protected Areas. The Wildlife Trusts are working with sea users, scientists, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. Do your bit for our Living Seas by supporting your local Wildlife Trust or checking out our Action Pages.