Sea anemones thrive on a special partnership
Green sea anemones have single-celled algae living in their tissues. The algae probably have a relatively safe place to live, but the sea anemone may get a good portion of its food from the algae, as well as some camouflage. Anemones living in dark crevasses are paler green.
Similar to their jellyfish relatives, sea anemones use their tentacles to sting and retrieve prey. Small fish, open snails, and other intertidal animals are caught by the tentacles, pulled into the mouth, and eaten. An anemone with tentacles tucked inside while underwater is probably eating; an anemone with tentacles tucked inside when out of the water is probably protecting its tentacles and mouth from drying and other damage.
Poking anemones may cause them to squirt out valuable water they need to stay hydrated during low tide, please observe gently.