With their soft bodies and crown of waving tentacles, these animals bring colour, complexity and life to our rocky shores and seabed habitats, supporting marine ecosystems in ways that are easy to miss at first glance.
Sea anemones are cnidarians, related to jellyfish and corals. Their tentacles are armed with microscopic stinging cells, used to capture plankton, small crustaceans and passing food particles from the water. By feeding in this way, anemones help regulate plankton populations and recycle nutrients back into the ecosystem. Some species, such as the Common Beadlet Anemone, can even survive exposure at low tide by pulling their tentacles in and sealing themselves against drying out.
Many UK sea anemones live fixed to rocks, shells or the seabed, forming long-lasting features of the marine landscape. In doing so, they provide shelter and refuge for other species. Small fish, crabs and shrimp can be found hiding among their tentacles, protected from predators. Others, like the elegant Plumrose Anemone, thrive on wrecks and harbour walls, transforming bare structures into rich, living habitats.
Sea anemones are also sensitive to changes in water quality and temperature, making them useful indicators of environmental health. Their presence in harbours, rock pools and offshore reefs reflects improving conditions in some areas, following reduced pollution and better management of coastal activities.
From fiery orange/red/purple Dahlia Anemones, multicoloured jewel anemones to vividly patterned Snakelocks Anemones, these animals add beauty as well as function to our seas. So next time you explore a rock pool or peer beneath a pier, take a moment to admire the sea anemones gently swaying with the tide—and appreciate the quiet but important role they play in keeping our marine ecosystems thriving.
Written by guest author, Dr Ray Ward, Reader of Environmental Sciences, School of Geography, Queen Mary University of London