Sorberacea were a monoorder and monofamilial class of

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

Tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ca ...

s. The single order of the class was ''Aspiraculata'', and the single family of that order was ''Hexacrobylidae''. In a taxonomic revision of the Tunicata in 2007, the name "Hexacrobylidae" was declared invalid and members of the family were included in the family

Molgulidae Molgulidae is a Family (biology), family of tunicates in the Class (biology), class Ascidiacea. Following a revision in 2007, the family Hexacrobylidae was synonymized with Molgulidae. Genera The World Register of Marine Species lists the follo ...

in the class

Ascidiacea Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" ...

.Sanamyan, K. (2007). Database of extant Ascidiacea. Version of 2 November 2007 They superficially resemble sea squirts but

prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

on invertebrates such as

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s. They also have some unique physical features that distinguish them from the

ascidiacea Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" ...

ns, including a severely reduced

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struc ...

, the retention of the

dorsal nerve cord The dorsal nerve cord is a unique feature to chordates, and it is mainly found in the Vertebrata chordate subphylum. The dorsal nerve cord is only one embryonic feature unique to all chordates, among the other four chordate features-- a notochord, ...

as adults, the superficial position of their

ganglion A ganglion is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system there are both sympatheti ...

and the unique

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

of the cells of their digestive tracts. The branchial syphon is large and surrounded by six large lobes; the cloacal syphon is small. They live exclusively in deep water and range in size from less than one inch (2 cm) to 2.4 inches (6 cm). Contrary to almost all tunicates, the members of this group are not filter-feeders, and instead capture and eat

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

s and small

s. They are solitary animals, found only in the deep sea.

Taxonomy

Order Aspiraculata * Family Hexacrobylidae ** Genus ''Gasterascidia'' - accepted as ''

Oligotrema ''Oligotrema'' is a genus of marine tunicates.Moreira da Rocha, R.; Gittenberger, A.; Sanamyan, K. (2015)''Oligotrema''.In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea Wor ...

'' Bourne, 1903 *** ''Gasterascidia lyra'' - accepted as ''

Oligotrema lyra ''Oligotrema'' is a genus of marine tunicates.Moreira da Rocha, R.; Gittenberger, A.; Sanamyan, K. (2015)''Oligotrema''.In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea Wor ...

'' Monniot C. & Monniot F., 1973 *** ''Gasterascidia sandersi'' - accepted as ''

Oligotrema sandersi ''Oligotrema'' is a genus of marine tunicates.Moreira da Rocha, R.; Gittenberger, A.; Sanamyan, K. (2015)''Oligotrema''.In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea Wor ...

'' (Monniot C. & Monniot F., 1968) ** Genus ''Hexadactylus'' - accepted as ''

Asajirus Asajirus is a genus of marine tunicates.Moreira da Rocha, R.; Sanamyan, K. (2015). Asajirus Kott, 1989. In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea World Database. Acc ...

'' Kott, 1989 *** ''Hexadactylus arcticus'' - accepted as ''

Asajirus indicus Asajirus is a genus of marine tunicates.Moreira da Rocha, R.; Sanamyan, K. (2015). Asajirus Kott, 1989. In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea World Database. Acc ...

'' (Oka, 1913) *** ''Hexadactylus eunuchus'' - accepted as ''

'' (Oka, 1913) *** ''Hexadactylus ledanoisi'' - accepted as ''

Asajirus ledanoisi Asajirus is a genus of marine tunicates.Moreira da Rocha, R.; Sanamyan, K. (2015). Asajirus Kott, 1989. In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea World Database. Acc ...

'' (Monniot C. & Monniot F., 1990) ** Genus ''

'' - now included in the family

*** ''

'' *** ''

Oligotrema psammites ''Oligotrema'' is a genus of marine tunicates.Moreira da Rocha, R.; Gittenberger, A.; Sanamyan, K. (2015)''Oligotrema''.In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea Wor ...

'' ** Genus ''Sorbera'' - accepted as ''

'' Bourne, 1903 *** ''Sorbera unigonas'' - accepted as ''

Oligotrema unigonas ''Oligotrema'' is a genus of marine tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (includi ...

'' (Monniot C. & Monniot F., 1974) *** ''Sorbera digonas'' - accepted as ''

'' Bourne, 1903

References

Tunicates Chordate orders Monotypic animal orders {{tunicata-stub