Tube-dwelling anemones or ceriantharians look very similar to
sea anemone
Sea anemones are a group of predation, predatory marine invertebrates of the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classifi ...
s but belong to an entirely different
class
Class or The Class may refer to:
Common uses not otherwise categorized
* Class (biology), a taxonomic rank
* Class (knowledge representation), a collection of individuals or objects
* Class (philosophy), an analytical concept used differentl ...
of
anthozoa
Anthozoa is a subphylum of marine invertebrates which includes the sea anemones, Scleractinia, stony corals and Alcyonacea, soft corals. Adult anthozoans are almost all attached to the seabed, while their larvae can disperse as part of the plank ...
ns. 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
A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this ce ...
-like
organelle
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the ...
s 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 wa ...
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
''Botrucnidifer'' 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 fea ...
''
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
''Hensenanthula'' is a genus of cnidarians belonging to the family Botrucnidiferidae.
The species of this genus are found in Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It c ...
''
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
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
reconstructions and
morphological assessment across the three families recovered
Arachnactidae as a well-supported
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
, but did not recover
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 ...
and
Botrucnidiferidae as
monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
, drawing into question the validity of the
Spirularia suborder
References
External links
Photos of Tube AnemonesTube-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