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Anemones

(Actiniaria)

Overview

Sea anemones are named after and resemble flowers, but they’re actually invertebrates related to corals and jellies. Their bodies consist of a soft, cylindrical stalk topped by an oral disc surrounded with venomous tentacles.

At their base, they sport a single adhesive foot, called a basal disc, which they use to attach to underwater surfaces like rocks or shells. Anemones can have anywhere from a dozen to a few hundred tentacles. These cnidarians come in a variety of colors, decorating a tide pool or reef like a garden of wildflowers.

Anemones are known to form symbiotic relationships with other animals; their most well-known alliance is with clownfish. Because of a protective mucous coating, clownfish are immune to an anemone’s stinging cells. They make their homes within the anemone’s tentacles, protected from predators; in return, the anemone eats the clownfish’s leftover meals.

At the National Aquarium, you’ll find 16 different species of sea anemones.

A Note from the Caretaker

Like jellies, coral and all other cnidarians, sea anemones have only one opening, which means food enters and waste exits from the same place.

Quick Facts

Learn more about anemones! Did you know that anemones can have anywhere from a dozen to a few hundred tentacles?

Anemones are found worldwide in all marine habitats. They can be found in a range of temperatures, from the cold water of the north Pacific to the warm water of the Caribbean, and live at various depths, from the shallower waters of the tidal zone up to depths of 1.8 miles (3,000 meters).

Anemones are carnivorous, feeding on tiny plankton or fish. Their stinging tentacles are triggered by the slightest touch, firing a harpoon-like filament called a nematocyst into their prey. Once injected with the paralyzing neurotoxin, the prey is guided into the mouth by the tentacles.

An anemone has a single opening in the center of an oral disc, by which it consumes food and excretes waste. At the Aquarium, they are fed pieces of shrimp, fish and krill.

Most anemones are small, but some can grow as large as 6.5 feet in diameter.

Most anemone species are non-threatened, but there are a few considered vulnerable.

Stinging cells deter many predators, but some animals can still make a meal of an anemone. Many species of fish, sea stars, snails and even sea turtles have been known to opportunistically feed on anemones.

Meet the Expert Jack Cover

As the National Aquarium's general curator, Jack Cover ensures that all animals in our care thrive in healthy, beautiful habitats.

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