The oldest fossil sea anemone ever found is around 500 million years old. Like its relatives, the jellyfish and corals, sea anemones have stinging cells. A small fish or shrimp touching its tentacles triggers a venom-filled mini-harpoon to fire. This stuns the prey which can then be pulled into the anemone’s mouth.
Most sea anemones attach themselves to rocks but a few float free and some live on the shells of hermit crabs. Anemones can live singly or in huge, colourful colonies.
Photo: Paul Naylor