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.
Thaliacea is a class of marine animals within the subphylum Tunicata, comprising the salps, pyrosomes and doliolids. Unlike their benthic relatives the ascidians, from which they are believed to have emerged, thaliaceans are free-floating (pelagic) for their entire lifespan. The group includes species with complex life cycles, with both solitary and colonial forms.
Larvaceans or appendicularians, class Appendicularia, are solitary, free-swimming tunicates found throughout the world's oceans. Like most tunicates, larvaceans are filter feeders. Unlike most other tunicates, they keep their tadpole-like shape as adults, with the notochord running through the tail. They can be found in the pelagic zone, specifically in the photic zone, or sometimes deeper. They are transparent planktonic animals, usually ranging from 2 mm (0.079 in) to 8 mm (0.31 in) in body length including the tail, although giant larvaceans can reach up to 10 cm (3.9 in) in length.
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 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.
The predatory tunicate, also known as the ghostfish, is a species of tunicate which lives anchored along deep-sea canyon walls and the seafloor. It is unique among other tunicates in that rather than being a filter feeder, it has adapted to life as an ambush predator. Its mouth-like siphon is quick to close whenever a small animal such as a crustacean or a fish drifts inside. Once the predatory tunicate catches a meal, it keeps its trap shut until the animal inside is digested. They are known to live in the Monterey Canyon at depths of 200–1,000 metres (660–3,280 ft). They mostly feed on zooplankton and tiny animals, and their bodies are roughly 5 inches (13 cm) across.
Botryllus schlosseri is a colonial ascidian tunicate. It is commonly known as the star tunicate, but it also has several other common names, including star ascidian and golden star tunicate. Colonies grow on slow-moving, submerged objects, plants, and animals in nearshore saltwater environments.
Aplidium californicum is a species of colonial sea squirt, a tunicate in the family Polyclinidae. It is commonly known as sea pork.
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.
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.
Ciona savignyi is a marine animal sometimes known as the Pacific transparent sea squirt or solitary sea squirt. It is a species of tunicates in the family Cionidae. It is found in shallow waters around Japan and has spread to the west coast of North America where it is regarded as an invasive species.
Molgula occulta is a species of solitary tunicate in the family Molgulidae. It is native to the north eastern Atlantic Ocean, the North Sea and the Mediterranean Sea. The specific name occulta means "tailless" and refers to the tunicate's larva, which lacks the tail found in some other species in the genus Molgula.
Polycarpa fibrosa is a species of tunicate in the family Styelidae. It is brown and globular and its outer surface is covered with a mat of fibrils. It normally lies buried in soft sediment on the seabed with only its two siphons protruding. It occurs in the Arctic Ocean and northern Atlantic Ocean. P. fibrosa was first identified and described by the American malacologist William Stimpson in 1852.
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.
Polyclinum planum, is a compound ascidian commonly known as the elephant ear tunicate. It is an ascidian tunicate in the family Polyclinidae. Ascidians are also known as sea squirts.
Polyandrocarpa is a genus of ascidian tunicates within the family Styelidae.
Phallusia mammillata is a solitary marine tunicate of the ascidian class found in the eastern Atlantic Ocean and the Mediterranean Sea.
Nephromyces is a genus of apicomplexans that are symbionts of the ascidian genus Molgula.
Molgula occidentalis is a species of marine invertebrate of the family Molgulidae. The scientific name of the species was validated and published for the first time in 1883 by Traustedt. It is a soft-bodied, intertidal ascidian, sac-like filter feeders in the subphylum tunicate characterized by a hard outer covering known as a “tunic,” abundant in the shallow subtidal and intertidal zones of the Northern Gulf of Mexico, where they establish pseudopopulations.
Tunicotheres is a monotypic genus of crabs in the family Pinnotheridae, and Tunicotheres moseri is the only species in the genus. This crab lives commensally in the atrial chamber of a small ascidian. It is found in the tropical western Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.
