The Sea lemon is a type of sea slug found in UK seas down to 300m and occasionally under boulders in rockpools on the low shore. They are often lemon-yellow in colour, but can be green, white or brown. Their body is covered in warty lumps and their markings are often blotchy. They have a ring of feathery gills near their rear end that they use to breathe. The Sea lemon feeds on sponges, mainly the Breadcrumb Sponge. They lay a long ribbon of eggs which are laid in a coil with one end attached to the seafloor - creating a beautiful egg rosette.
How to identify
A large sea slug, up to 12cm long. Normally found under rocks or bounders in rockpools on the low shore or beneath the sea. They have a warty bumpy body, with yellowish and often blotchy colouration. Confusingly, they can also be green, white and brown.
The Sea lemon's entire life cycle last only a single year. Juveniles appear in the late summer and grow into adults throughout autumn and winter. They then mate and spawn in spring before dying.
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.