Sea anemones are cnidarians. They are closely related to jellies and corals.
  • Size

    Range in size from approximately .5 inches (1.3 cm) to more than 36 inches (91 cm) in diameter depending on the species.
  • Diet

    Diet varies depending on species.
  • Range

    Occur throughout the world’s oceans.
  • Habitat

    Habitats range from tropical reefs to deep ocean environments.

Physical Characteristics

  • Body is composed of a pedal disc, or foot, a cylindrical body, a central mouth and an array of tentacles.
  • May range in size from approximately .5 inches (1.3 cm) to more than 36 inches (91 cm) in diameter depending on the species.
  • Characterized by the presence of stinging cells called nematocysts. These cells are small venomous barbs that line the tentacles and number in the hundreds of thousands.
  • Coloration varies widely between species.

Animal Fact

Anemones do not permanently attach to the substrate. They can move if food is scarce or a predator threatens them.

Diet / Feeding

  • Diet varies depending on species; consists of plankton, crabs, fish and occasionally larger prey such as sea stars and jellies.
  • Nematocysts aid in the capture of prey. The stinging cells are used to immobilize prey, so it can be moved to the mouth by the tentacles.
  • Extends tentacles to catch prey as it drifts past the anemone.

Range / Habitat

  • Occur throughout the world’s oceans.
  • Found in a variety of habitats, from tropical reefs to deep ocean environments.
  • Widest variety of anemone species found in coastal tropical waters.

Reproduction & Growth

  • May reproduce sexually or asexually depending on species.
  • Asexual reproduction occurs by means of budding, in which part of the anemone will break off and form a new, identical, organism. Anemones can also split longitudinally or grow new organisms from their basal discs. In both cases, the new organism is genetically identical to the original organism.
  • Sexual reproduction occurs by means of broadcast spawning.
  • Unlike other classes of cnidarians, anthozoans, including sea anemones, entirely lack the free-swimming medusae stage of the life cycle. Instead, the fertilized egg develops into a planula, which then develops directly into primary polyp.

Additional Information

  • Sea anemones are cnidarians, closely related to jellies and corals.
  • Anemones do not permanently attach to the substrate. They can move if food is scarce or a predator threatens them. Limited movement is achieved by either slowly gliding along on the pedal disc tor detaching completely and moving with the current. Some can even “swim” by bending their bodies or lashing their tentacles. A few species will turn their bodies upside down and travel along the bottom on their tentacles.
  • Some species known for their symbiotic relationship with clownfish. The fish’s thick coating of mucus protects it from the potentially deadly sting of the anemone. The anemone provides the clownfish with protection from predators and scraps from leftover meals. The fish removes parasites and dead skin from its host, provides protection from some predators and, by swimming, ventilates the anemone.
  • Boiled and spiced anemones are eaten throughout the Mediterranean and in some parts of the Indo-Pacific. Otherwise anemones have no enemies aside from sea slugs and a few fishes.
  • Several species of hermit crab carry an anemone about on their shells. When the hermit crab moves to a larger shell, it carefully places the anemone on the new shell. The anemone protects and camouflages the hermit crab. In return, the anemone is able to grab bits of food when the hermit crab is feeding.

Species at Georgia Aquarium

  • Fish-eating anemone (Urticina piscivore) – eastern Pacific from Alaska to southern California, commonly 8 inches (20 cm) tall and 10 inches (26 cm) in diameter.
  • White-spotted rose anemone (Urticina lofotensis) – Pacific from southeast Alaska to San Diego, California and in the North Atlantic, commonly 4 inches (10 cm) in diameter.
  • Giant green anemone (Anthopleura xanthogrammica) – Pacific from Alaska south to Panama, also found in Hudson Bay, Canada and the eastern coast of Russia, may grow to be 12 inches (30 cm) tall and 7-10 inches (17-25 cm) in diameter.
  • Magnifica anemone (Heteractis magnifica) – Indo-Pacific from the Red Sea to Samoa, commonly 12-20 inches (300-500mm) in diameter but may reach 39 inches (1 m) in diameter.
  • Long tentacle anemone (Macrodactyla doreensis) – west Indo-Pacific from southern Japan to the Philippines, New Guinea, northern Australia and eastern Indonesia, commonly 19 inches (48 cm) in diameter.
  • Bubbletip anemone (Entacmaea quadricolor) – Indo-Pacific from the Red Sea to Samoa, may grow 12 inches (30 cm) in diameter.
  • Carpet anemone (Stichodactyla gigantea) – Indo-Pacific from the Red Sea to the Solomon Islands, may reach 20 inches (50 cm) in diameter.
  • Rock flower anemone (Epicystis crucifer)

Sources

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