Octineon is the sole genus of sea anemones in the monotypic family Octineonidae.
Tube-dwelling anemones or ceriantharians look very similar to sea anemones but belong to an entirely different subclass 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 subclass, 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 New Latin, commemorates the French zoologist Henri Milne-Edwards.
Cadlina is a genus of sea slugs, dorid nudibranchs, shell-less marine gastropod mollusks historically classified in the family Chromodorididae. Recent research by R.F. Johnson in 2011 has shown that Cadlina does not belong to the family Chromodorididae. She has therefore brought back the name Cadlinidae from synonymy with Chromodorididae. The family Cadlinidae also includes the genus AldisaBergh, 1878.
Dendronotus is a genus of sea slugs, nudibranchs, marine gastropod molluscs in the superfamily Tritonioidea.
Nematostella is a genus of sea anemones in the family Edwardsiidae. Of the three species in the genus, the best known is the starlet sea anemone, which has been extensively studied as a model organism in fields such as genetics, evolution, and ecology. The defining morphological apomorphy of Nematostella is the presence of nematosomes.
Amphianthus is a genus of sea anemones. It is the only genus in the monotypic family Amphianthidae.
Epiactis is a genus of sea anemones in the family Actiniidae. There are about nineteen recognised species and the type species is Epiactis prolifera.
Isanthidae is a small family of sea anemones in the class Anthozoa.
Isozoanthus is a genus of anemone-like anthozoans in the order Zoantharia.
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.
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.
Cerianthus is a genus of tube-dwelling anemones in the family Cerianthidae. Members of the genus are found worldwide. They are predators, scavengers and omnivores.
Zoanthus is a genus of anthozoans in the family Zoanthidae. It is the type genus for its family and order.
Actinostolidae is a family of sea anemones in the order Actiniaria. Members of this family are deep sea species, with some occurring at hydrothermal vents.
Bolocera is a genus of sea anemone in the family Actiniidae.
Actinernidae is a family of sea anemones. It contains the following genera and species:
Epiparactis is a genus of sea anemones of the family Actinoscyphiidae. It currently includes only one species.
Anthosactis is a genus of cnidarians belonging to the family Actinostolidae.
