Tube-dwelling anemones or ceriantharians look very similar to sea anemones but belong to an entirely different class of anthozoans. They are solitary, living buried in soft sediments. Tube anemones live inside and can withdraw into tubes, which are composed of a fibrous material made from secreted mucus and threads of nematocyst-like organelles known as ptychocysts. Within the tubes of these ceriantharians, more than one polyp is present, which is an exceptional trait because species that create tube systems usually contain only one polyp per tube. Ceriantharians were formerly classified in the taxon Ceriantipatharia along with the black corals but have since been moved to their own class, Ceriantharia.
Edwardsia is a genus of sea anemones, the type of the family Edwardsiidae. They have eight mesenteries and live in tubes in the sand. The name, in Neo-Latin, commemorates the French zoologist Henri Milne-Edwards.
Corallimorpharia is an order of marine cnidarians closely related to stony or reef building corals (Scleractinia). They occur in both temperate and tropical climates, although they are mostly tropical. Temperate forms tend to be very robust, with wide and long columns, whereas tropical forms tend to have very short columns with a wide oral disc and very short tentacles. The tentacles are usually arranged in rows radiating from the mouth. Many species occur together in large groups, although there are recorded instances of individuals. In many respects, they resemble the stony corals, except for the absence of a stony skeleton. Morphological and molecular evidence suggests that they are very closely related to stony corals.
Rhodactis is genus of mushroom corals which are characterized by large individual polyps that are often reminiscent of a mushroom. Rhodactis are related to stony corals but do not produce a stony skeleton.
Corynactis is a genus of colonial anthozoans similar in appearance to sea anemones and in body format to scleractinian stony corals. These animals are cnidarians in the family Corallimorphidae. Large unidentified polyps of this genus feed on the crown-of-thorns seastar Acanthaster planci and may help control the crown-of-thorns population.
Bunodactis is a genus of sea anemones in the family Actiniidae.
Epiactis is a genus of sea anemones in the family Actiniidae. There are about nineteen recognised species and the type species is Epiactis prolifera.
Parazoanthus is a genus of anemone-like anthozoans in the order Zoantharia.
Urticina is a genus of relatively large and often colorful sea anemones in the family Actiniidae from the North Pacific, North Atlantic and Arctic Oceans.
Actinia is a genus of sea anemones in the family Actiniidae. Actinia display a rare form of heteromorphosis in which a cut inflicted on a specimen can develop into a second mouth.
Haloclavidae is a family of sea anemones. Members of the family are found worldwide and many live largely buried in soft substrates with only their oral disc and tentacles protruding.
Urticina eques is a species of sea anemone in the family Actiniidae. It is commonly known as the white-spotted rose anemone or strawberry anemone.
Holaxonia is a suborder of soft corals, a member of the phylum Cnidaria. Members of this suborder are sometimes known as gorgonians and include the sea blades, the sea fans, the sea rods and the sea whips. These soft corals are colonial, sessile organisms and are generally tree-like in structure. They do not have a hard skeleton composed of calcium carbonate but have a firm but pliable, central axial skeleton composed of a fibrous protein called gorgonin embedded in a tissue matrix, the coenenchyme. In some genera this is permeated with a calcareous substance in the form of fused spicules. Members of this suborder are characterized by having an unspiculated axis and often a soft, chambered central core. The polyps have eight-fold symmetry and in many species, especially in the families Gorgoniidae and Plexauridae, contain symbiotic photosynthetic algae called zooxanthellae. These soft corals are popular in salt water aquaria.
Anemonia is a genus of sea anemones belonging to the family Actiniidae.
Palythoa is a genus of anthozoans in the order Zoantharia.
Aiptasiidae is a family of sea anemones, comprising the following genera:
Merulinidae is a family of reef-building stony corals.
Actinostella is a genus of sea anemones in the family Actiniidae.
Gyrostoma is a genus of cnidarians belonging to the family Actiniidae.
