Sea slater

Sea Slater

Sea Slater ©Mark Robinson

Sea slater

Scientific name: Ligia oceanica
These little critters are related to the woodlice you find in your garden and play a very important role on rocky shores.

Species information


Length: up to 3cm Average Lifespan: 2.5 years

Conservation status


When to see

January to December


The sea slater is a type of crustacean, closely related to the woodlouse. Also known as the Sea roach, they live on rocky shores all around the UK. They hide away in crevices and under rocks during the day and come out at night to feed.

Like the terrestrial woodlouse, they play an important role in the ecosystem. They are detritivores and munch on decaying material like seaweed; this helps break it down and increase the surface area for decomposition by bacteria and fungi. The best time to look for sea slaters is late in the evening or at night, when they leave their hidey-holes in search of food.

How to identify

Turn over rocks on the seashore and this is the woodlouse-like creature you may find. Up to 3cm long, it has a grey oval, segmented and flattened body with long antennae and lots of legs - just like its well-known terrestrial relative. It also has very large, black eyes.


Found around all UK coasts.

Did you know?

Sea slaters have gills - but don't live underwater! That's why you find them in damp environments, like in crevices or under rocks.

How people can help

Take part in a beach clean to remove strandline litter by hand. This has a much lower impact than mechanical beach cleaning. If organising a beach clean, encourage participants to leave natural debris on the beach - including decaying/dry seaweed. It is an important part of the ecosystem! If possible, remove the litter from the seaweed (we know it's tough when it's all tangled up!) and leave the seaweed on the beach.

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.