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Inhabitants of Oregon's Tidepools: Anemones

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.Shaped overall like shallow bowls with ultra-thick bottoms attached to the substrate, sea anemones may look more like flowers than like animals—especially the ones that are green.  Pointed “petals” around the top rim are stinger-armed tentacles that frame the central disc, the mouth of the animal.  The floor of the central disc is smooth with a doughnut-shaped lump in the middle, while the outside of the body, below the tentacles, is usually a darker green and rough, and is often flecked with bits of shell.  Most Oregon intertidal sea anemones are olive to bright green (some species have splashes of other colors).  Depending on species, age, and environment, some of our tidepool sea anemones can grow up to 10” across.

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.

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