FaunaHub

Sea Anemone (order Actiniaria)

Marine invertebrateCnidarianCoral relative

Magnificent sea anemone (Heteractis magnifica) with its column of tentacles.

Magnificent sea anemone (Heteractis magnifica), Red Sea.

Image: Diego Delso, CC BY-SA 4.0, via Wikimedia Commons.

Overview

Sea anemones (order Actiniaria) are soft-bodied marine animals — close relatives of corals and jellyfish in the phylum Cnidaria. Essentially a single large polyp without a hard skeleton, an anemone is a column topped by a ring of stinging tentacles around a central mouth. They are named after a land flower because of their colourful, petal-like crown of tentacles.

Anemones are famous for their partnership with clownfish (anemonefish), which shelter unharmed among the stinging tentacles — one of the most celebrated relationships in the sea.

Note: anemones' tentacles bear stinging cells used to capture prey; some can give a noticeable sting, so wild anemones are best not handled. Treat details as general and verify against authoritative sources.

Habitat & Range

Sea anemones live in oceans worldwide, from tropical reefs to cold and deep seas, usually attached to rocks, reefs, shells, or the seabed. Some attach to hard surfaces, others anchor in sand or mud, and a few live on the shells carried by hermit crabs.

Diet

Sea anemones are carnivores. They capture prey — small fish, shrimp, plankton, and other animals — using tentacles armed with microscopic stinging cells (nematocysts) that fire on contact, then draw the food to the central mouth. Many reef anemones also host symbiotic algae that supply extra energy.

Behavior

Although they look plant-like and usually stay put, anemones are animals and can slowly glide on their base, and some detach to relocate if conditions change. They retract their tentacles when disturbed or exposed. Anemones may reproduce sexually or by splitting and budding, and some form clonal groups covering a surface.

Human Interaction & Conservation

Sea anemones are a beloved part of reef life, especially through the clownfish partnership made famous in popular culture. They are sensitive to the same pressures as other reef animals — warming seas can cause anemones, like corals, to bleach. Wild anemones should be observed without touching. For current status, consult authoritative sources.

More photos of the sea anemone

A clownfish sheltering among the tentacles of a sea anemone.

A clownfish sheltering in a sea anemone — a classic partnership.

Image: Diego Delso, CC BY-SA 4.0, via Wikimedia Commons.

Frequently Asked Questions — Sea Anemone

Is a sea anemone a plant or an animal?
A sea anemone is an animal — a cnidarian, closely related to corals and jellyfish. Its flower-like crown of tentacles gives it a plant-like look and its name, but it captures prey, can move slowly, and is firmly an animal.
How do clownfish live in a sea anemone without being stung?
Clownfish (anemonefish) have a protective mucus coating and behaviour that let them live among the anemone's stinging tentacles largely unharmed. In return, the fish gains shelter from predators while helping deter the anemone's enemies and keeping it clean — a mutually beneficial partnership.
Do sea anemones sting people?
Their tentacles carry stinging cells used to catch prey, and some species can deliver a noticeable sting to people, while many are too weak to be felt through skin. As a precaution, wild anemones are best observed rather than handled. This page does not provide medical advice.
Can sea anemones move?
Yes, slowly. Although anemones usually stay anchored, many can glide gradually on their base, and some can detach and relocate if needed. They also retract their tentacles when disturbed.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.