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 the Ancient Greek word (), meaning "the depths". ...

Tunicate Tunicates are marine invertebrates belonging to the subphylum Tunicata ( ). This grouping 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 ...

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 in the class

Ascidiacea Ascidiacea, commonly known as the ascidians or sea squirts, is a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer test or "tunic" made of the polysacchari ...

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

prey Predation is a biological interaction in which 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 ki ...

on invertebrates such as

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

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

ascidiacea Ascidiacea, commonly known as the ascidians or sea squirts, is a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer test or "tunic" made of the polysacchari ...

ns, including a severely reduced

pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

, the retention of the

dorsal nerve cord The dorsal nerve cord is an anatomical feature found in chordate animals, mainly in the subphyla Vertebrata and Cephalochordata, as well as in some hemichordates. It is one of the five embryonic features unique to all chordates, the other fo ...

as adults, the superficial position of their

ganglion A ganglion (: ganglia) 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 ...

and the unique

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

of the cells of their

digestive tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...

s. 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 ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s and small

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

Taxonomy

Order Aspiraculata * Family Hexacrobylidae ** Genus ''Gasterascidia'' - accepted as '' Oligotrema'' Bourne, 1903 *** ''Gasterascidia lyra'' - accepted as '' Oligotrema lyra'' Monniot C. & Monniot F., 1973 *** ''Gasterascidia sandersi'' - accepted as '' Oligotrema sandersi'' (Monniot C. & Monniot F., 1968) ** Genus ''Hexadactylus'' - accepted as '' Asajirus'' Kott, 1989 *** ''Hexadactylus arcticus'' - accepted as '' Asajirus indicus'' (Oka, 1913) *** ''Hexadactylus eunuchus'' - accepted as '' Asajirus indicus'' (Oka, 1913) *** ''Hexadactylus ledanoisi'' - accepted as '' Asajirus ledanoisi'' (Monniot C. & Monniot F., 1990) ** Genus '' Oligotrema'' - now included in the family Molgulidae *** '' Oligotrema lyra'' *** '' Oligotrema psammites'' ** Genus ''Sorbera'' - accepted as '' Oligotrema'' Bourne, 1903 *** ''Sorbera unigonas'' - accepted as '' Oligotrema unigonas'' (Monniot C. & Monniot F., 1974) *** ''Sorbera digonas'' - accepted as '' Oligotrema psammites'' Bourne, 1903

References

Tunicates Tunicate orders Monotypic animal orders Obsolete animal taxa {{tunicata-stub