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. The subphylum was at one time called Urochordata, and the term urochordates is still sometimes used for these animals. They are the only chordates that have lost their myomeric segmentation, with the possible exception of the 'seriation of the gill slits'. However, doliolids still display segmentation of the muscle bands.
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 "tunic" made of a polysaccharide.
Ciona is a genus of sea squirts in the family Cionidae.
Ciona intestinalis is an ascidian, a tunicate with very soft tunic. Its Latin name literally means "pillar of intestines", referring to the fact that its body is a soft, translucent column-like structure, resembling a mass of intestines sprouting from a rock. It is a globally distributed cosmopolitan species. Since Linnaeus described the species, Ciona intestinalis has been used as a model invertebrate chordate in developmental biology and genomics. Studies conducted between 2005 and 2010 have shown that there are at least two, possibly four, sister species. More recently it has been shown that one of these species has already been described as Ciona robusta. By anthropogenic means, the species has invaded various parts of the world and is known as an invasive species.
Corella willmeriana is a solitary tunicate in the family Corellidae. It is native to the eastern Pacific Ocean where it lives on the seabed at depths down to about 75 m (250 ft) between Alaska and California.
Ecteinascidia turbinata, commonly known as the mangrove tunicate, is a species of sea squirt species in the family Perophoridae. It was described to science in 1880 by William Abbott Herdman. The cancer drug trabectedin is isolated from E. turbinata.
Ascidiella aspersa, the European sea squirt, is a species of solitary sea squirts native to the northeastern Atlantic, from the Mediterranean Sea to Norway. They possess oval bodies up to 50 to 130 mm in length. Their branchial siphons are conical and positioned at the top of the body. They possess six to eight lobes. The atrial siphons are located at the upper third of the side of the body and possess six lobes. The body is covered by a firm transparent test that is greyish to brown in color. The test often snag detritus that remain loosely attached to the animal. When expanded, at most 40 tentacles can be observed on the inside surface of the branchial wall. Both the openings of the branchial and atrial siphons possess lighter colored ridges on their rims. They may also be frilled at times. A. aspersa are attached to the substrates by the left side of their bodies. They can be found in dense groups of unfused individuals on hard surfaces like rocks. at depths of up to 90 m (300 ft).
Atriolum robustum is a colonial tunicate or sea squirt in the family Didemnidae. It is native to the western and central Indo-Pacific where it is usually found anchored to a hard surface in shallow water.
Didemnum molle is a species of colonial tunicate in the family Didemnidae. It is commonly known as the tall urn ascidian, the green barrel sea squirt or the green reef sea-squirt. It is native to the Red Sea and the tropical waters of the Indo-Pacific region.
Didemnum vexillum is a species of colonial tunicate in the family Didemnidae. It is commonly called sea vomit, marine vomit, pancake batter tunicate, or carpet sea squirt. It is thought to be native to Japan, but it has been reported as an invasive species in a number of places in Europe, North America and New Zealand. It is sometimes given the nickname "D. vex" because of the vexing way in which it dominates marine ecosystems when introduced into new locations, however the species epithet vexillum actually derives from the Latin word for flag, and the species was so named because of the way colonies' long tendrils appear to wave in the water like a flag.
Ascidia mentula is a species of solitary tunicate. It is found in the north east Atlantic Ocean, the Mediterranean Sea and Black Sea. It occurs round the coasts of Britain but is seldom seen on the east coast of England or Scotland.
Molgula citrina is a species of solitary tunicate in the family Molgulidae. It is found on both sides of the northern Atlantic Ocean and in the Arctic Ocean. In 2008 it was found in Kachemak Bay in Alaska, the first time it had been detected in the Pacific Ocean.
Polycarpa pomaria is a species of tunicate or sea squirt in the family Styelidae. It is native to the northeastern Atlantic Ocean where it lives on the seabed at depths down to about 450 metres (1,500 ft).
Dendrodoa grossularia is a species of tunicate or sea squirt in the family Styelidae, commonly known as the baked bean ascidian. It is native to the northeastern Atlantic Ocean where it is common in shallow water and on the lower shore in exposed rocky sites.
Phallusia mammillata is a solitary marine tunicate of the ascidian class found in the eastern Atlantic Ocean and the Mediterranean Sea.
Boltenia villosa is a species of tunicate, a marine invertebrate of the family Pyuridae. Common names include the spiny-headed tunicate, the hairy sea squirt, the stalked hairy sea squirt and the bristly tunicate. This species was first described in 1864 by the American marine biologist William Stimpson who gave it the name Cynthia villosa. It was later transferred to the genus Boltenia. The type locality is Puget Sound, Washington state, United States.
Ciona robusta is a species of marine invertebrate in the genus Ciona of the family Cionidae. The holotype was collected on the northeastern coast of Honshu Island, Japan. Populations of Ciona intestinalis known as Ciona intestinalis type A found in the Mediterranean Sea, the Pacific Ocean, east coast of North America, and the Atlantic coasts of South Africa have been shown to be Ciona robusta.
Cnemidocarpa finmarkiensis is a species of solitary ascidian tunicate in the family Styelidae. Common names include broad base sea squirt, orange sea squirt, red sea squirt, shiny orange sea squirt, shiny red tunicate and Finmark's tunicate. It is native to shallow waters in the northern and northeastern Pacific Ocean.
Pyura haustor is a species of sessile ascidian, or sea squirt, that lives in coastal waters in the north-eastern Pacific Ocean, attached to rocks or artificial structures. Common names for this species include the wrinkled seapump, the wrinkled sea squirt and the warty tunicate.
Halocynthia igaboja, commonly known as the sea hedgehog, the bristly tunicate or spiny sea squirt, is a species of tunicate in the family Pyuridae. It is native to the northeastern Pacific Ocean. This species was first described in 1906 by the Japanese marine biologist Asajiro Oka, who gave it the name Cynthia ritteri. It was later transferred to the genus Halocynthia.
