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 coral Antipatharians, also known as black corals or thorn corals, are an order of soft deep-water corals. These corals can be recognized by their jet-black or dark brown chitin skeletons, surrounded by the polyps (part of coral that is alive). Antipat ...

s but have since been moved to their own subclass, Ceriantharia. Ceriantharians have a crown of tentacles that are composed of two whorls of distinctly different sized tentacles. The outer whorl consists of large tentacles that extend outwards. These tentacles taper to points and are mostly used in food capture and defence. The smaller inner tentacles are held more erect than the larger lateral tentacles and are used for food manipulation and ingestion. A few species such as '' Anactinia pelagica'' are

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

and are not attached to the bottom; instead, they have a gas chamber within the pedal disc, allowing them to float upside down near the surface of the water.

Taxonomy

;Order Spirularia * Family Botrucnidiferidae Carlgren, 1912 ** Genus '' Angianthula'' Leloup, 1964 ** Genus '' Atractanthula'' Leloup, 1964 ** Genus '' Botruanthus'' McMurrich, 1910 ** Genus '' Botrucnidiata'' Leloup, 1932 ** Genus '' Botrucnidifer'' Carlgren, 1912 ** Genus ''

Calpanthula ''Calpanthula'' is a genus of cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing featu ...

'' van Beneden, 1897 ** Genus '' Cerianthula'' Beneden, 1898 ** Genus '' Gymnanthula'' Leloup, 1964 ** Genus '' Hensenanthula'' van Beneden, 1897 ** Genus '' Ovanthula'' van Beneden, 1897 ** Genus '' Sphaeranthula'' Leloup, 1955 * Family

Cerianthidae Cerianthidae is a family of tube-dwelling anemones in the order Spirularia of the subclass Ceriantharia. Genera The World Register of Marine Species includes the following genera in the family: * ''Anthoactis'' Leloup, 1932 * ''Apiactis'' Bene ...

Milne-Edwards & Haime, 1852 ** Genus ''

Anthoactis ''Anthoactis'' is a genus of cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing featur ...

'' Leloup, 1932 ** Genus ''

Apiactis ''Apiactis'' is a genus of cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature ...

'' van Beneden, 1897 ** Genus ''

Bursanthus ''Bursanthus'' is a genus of cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing featur ...

'' Leloup, 1968 ** Genus ''

Ceriantheomorphe ''Ceriantheomorphe'' is a genus of tube-dwelling anemones in the family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of ...

'' Carlgren, 1931 ** Genus ''

Ceriantheopsis ''Ceriantheopsis'' is a genus of tube-dwelling anemones in the family Cerianthidae. Members of the genus are found only in the Atlantic Ocean. They are predators, scavengers and omnivore An omnivore () is an animal that has the ability to ...

'' Carlgren, 1912 ** Genus ''

Cerianthus ''Cerianthus'' is a genus of tube-dwelling anemones in the Family (biology), family Cerianthidae. Members of the genus are found worldwide. They are Predation, predators, scavengers and omnivores. Characteristics Members of this genus do not hav ...

'' Delle Chiaje, 1830 ** Genus ''

Engodactylactis ''Engodactylactis'' is a genus of cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing f ...

'' Leloup, 1942 ** Genus '' Isodactylactis'' Carlgren, 1924 ** Genus '' Nautanthus'' Leloup, 1964 ** Genus '' Pachycerianthus'' Roule, 1904 ** Genus '' Paradactylactis'' Carlgren, 1924 ** Genus '' Parovactis'' Leloup, 1964 ** Genus '' Peponactis'' van Beneden, 1897 ** Genus '' Plesiodactylactis'' Leloup, 1942 ** Genus '' Sacculactis'' Leloup, 1964 ** Genus '' Solasteractis'' van Beneden, 1897 ** Genus '' Synarachnactis'' Carlgren, 1924 ** Genus '' Syndactylactis'' Carlgren, 1924 ** Genus '' Trichactis'' Leloup, 1964 ;Order Penicillaria * Family Arachnactidae McMurrich, 1910 ** Genus '' Anactinia'' Annandale, 1909 ** Genus '' Arachnactis'' Sars, 1846 ** Genus '' Arachnanthus'' Carlgren, 1912 ** Genus '' Dactylactis'' van Beneden, 1897 ** Genus '' Isapiactis'' Carlgren, 1924 ** Genus '' Isarachnactis'' Carlgren, 1924 ** Genus '' Isarachnanthus'' Carlgren, 1924 ** Genus '' Isovactis'' ** Genus '' Ovactis'' ** Genus '' Paranactinia'' A 2020 integrative study incorporating molecular phylogenetic reconstructions and morphological assessment across the three families recovered Arachnactidae as a well-supported clade, but did not recover

and Botrucnidiferidae as monophyletic, drawing into question the validity of the Spirularia suborder

References

External links

Photos of Tube Anemones

Tube-dwelling anemone toxins have pharmacological potential, mapping study shows
on: Eurekalert!, 29 October 2020. Source: Fundação de Amparo à Pesquisa do Estado de São Paulo {{Taxonbar, from=Q245695 Anthozoa Animal classes