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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 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'. Some tunicates live as solitary individuals, but others replicate by budding and become colonies, each unit being known as a zooid. They are marine filter feeders with a water-filled, sac-like body structure and two tubular openings, known as siphons, through which they draw in and expel water. During their respiration and feeding, they take in water through the incurrent (or inhalant) siphon and expel the filtered water through the excurrent (or exhalant) siphon. Most adult tunicates are sessile, immobile and perman ...
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Chordata
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five synapomorphies include a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name “chordate” comes from the first of these synapomorphies, the notochord, which plays a significant role in chordate structure and movement. Chordates are also bilaterally symmetric, have a coelom, possess a circulatory system, and exhibit metameric segmentation. In addition to the morphological characteristics used to define chordates, analysis of genome sequences has identified two conserved signature indels (CSIs) in their proteins: cyclophilin-like protein and mitochondrial inner membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cephalochordates. These CSIs pr ...
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Larvacea
Larvaceans, 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 live in the pelagic zone, specifically in the photic zone, or sometimes deeper. They are transparent planktonic animals, generally less than in body length, excluding the tail. Anatomy The adult larvaceans resemble the tadpole-like larvae of most tunicates. Like a common tunicate larva, the adult Appendicularia have a discrete trunk and tail. Larvaceans produce a "house" made of mucopolysaccharides and cellulose. In most species, the house surrounds the animal like a bubble. Even for species in which the house does not completely surround the body, such as ''Fritillaria'', the house is always present and attached to at least one surface. These houses are discarded and replaced regularly as the animal grows in size and its filters become clogged; in '' Oikopleura'', a house is kept for n ...
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Larvaceans
Larvaceans, 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 live in the pelagic zone, specifically in the photic zone, or sometimes deeper. They are transparent planktonic animals, generally less than in body length, excluding the tail. Anatomy The adult larvaceans resemble the tadpole-like larvae of most tunicates. Like a common tunicate larva, the adult Appendicularia have a discrete trunk and tail. Larvaceans produce a "house" made of mucopolysaccharides and cellulose. In most species, the house surrounds the animal like a bubble. Even for species in which the house does not completely surround the body, such as ''Fritillaria'', the house is always present and attached to at least one surface. These houses are discarded and replaced regularly as the animal grows in size and its filters become clogged; in ''Oikopleura'', a house is kept for no ...
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Salp
A salp (plural salps, also known colloquially as “sea grape”) or salpa (plural salpae or salpas) is a barrel-shaped, planktic tunicate. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient examples of jet propulsion in the animal kingdom. The salp strains the pumped water through its internal feeding filters, feeding on phytoplankton. Distribution Salps are common in equatorial, temperate, and cold seas, where they can be seen at the surface, singly or in long, stringy colonies. The most abundant concentrations of salps are in the Southern Ocean (near Antarctica), where they sometimes form enormous swarms, often in deep water, and are sometimes even more abundant than krill. Since 1910, while krill populations in the Southern Ocean have declined, salp populations appear to be increasing. Salps have been seen in increasing numbers along the coast of Washington. Life cycle Salps have a complex life cycle, with an obligatory ...
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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" made of a polysaccharide. Ascidians are found all over the world, usually in shallow water with salinities over 2.5%. While members of the Thaliacea and Larvacea (Appendicularia) swim freely like plankton, sea squirts are sessile animals after their larval phase: they then remain firmly attached to their substratum, such as rocks and shells. There are 2,300 species of ascidians and three main types: solitary ascidians, social ascidians that form clumped communities by attaching at their bases, and compound ascidians that consist of many small individuals (each individual is called a zooid) forming colonies up to several meters in diameter. Sea squirts feed by taking in water through a tube, the oral siphon. The water enters th ...
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Yarnemia
''Yarnemia ascidiformis'' is a fossil tentatively classified as a tunicate. While ''Y. ascidiformis'' looks similar to tunicates, the oldest unequivocal tunicate, ''Shankouclava'' dates to the Cambrian period, while ''Y. ascidiformis'' is Ediacaran in age. Etymology The generic name ''Yarnemia'' comes from the village of Yarnema near which the first specimens were found. The specific epithet, ''ascidiformis'', refers to the likeness to ascidians. See also Other Ediacaran biota tentatively identified as tunicates include * ''Ausia fenestrata'' * ''Burykhia hunti ''Burykhia hunti'' is a Precambrian fossil from the White Sea region of Russia dating to . It is considered of ascidian affinity, due to the sac-like morphology and a series of distinctly perforated bands reminiscent of a tunicate pharynx. If ' ...'' References Ediacaran life Tunicate genera Prehistoric chordate genera Fossil taxa described in 1984 {{paleo-deuterostome-stub ...
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Shankouclava
''Shankouclava'' is an extinct genus of tunicate. It represents the oldest, unequivocal genus of tunicates, from 520 million years ago. It has been found in the Lower Cambrian Maotianshan Shale at Shankou village, Anning, near Kunming (South China South China () is a geographical and cultural region that covers the southernmost part of China. Its precise meaning varies with context. A notable feature of South China in comparison to the rest of China is that most of its citizens are not ...). Each of the eight specimens found and used for description were isolated, suggesting that the genus was solitary and not colonial. The generic name is composed of the fossil locality, Shankou, and the Latin word ''clava'' (club-shaped). ''Shankouclava'' had a soft, sac-like body that was elongated and pointed proximally. The body lengths of individuals vary from 2 cm (0.8 in) to 4 cm (1.6 in). References Tunicate genera Prehistoric chordate genera Foss ...
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Vertebrates
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish ( sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do ...
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Polycarpa Aurata
''Polycarpa aurata'', also known as the ox heart ascidian, the gold-mouth sea squirt or the ink-spot sea squirt, is a species of tunicate in the family Styelidae. Description ''Polycarpa aurata'' grows to a height of . It has an urn-shaped, hollow body with two siphons, one at the top and the other on the side. The body colour of this tunicate is white with purple and orange patches and purple lines. The inside is yellow or orange and this is visible around the rim of the siphons. Distribution This species is found in the tropical eastern Indian Ocean and the western Pacific Ocean. Its range includes the Philippines, Indonesia and northern Australia. Its depth range is . Biology Tunicates feed by drawing water in through the branchial siphon at the top, filtering out phytoplankton, bacteria and other food particles, before expelling the water through the atrial siphon at the side. Sometimes hydroids and algae grow on the outside of the tunicate and nudibranch Nudibranch ...
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Filter Feeder
Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish (including some sharks). Some birds, such as flamingos and certain species of duck, are also filter feeders. Filter feeders can play an important role in clarifying water, and are therefore considered ecosystem engineers. They are also important in bioaccumulation and, as a result, as indicator organisms. Fish Most forage fish are filter feeders. For example, the Atlantic menhaden, a type of herring, lives on plankton caught in midwater. Adult menhaden can filter up to four gallons of water a minute and play an important role in clarifying ocean water. They are also a natural check to the deadly red tide. Extensive article on the role of menhaden in the ecosystem and possible re ...
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Doliolida
The Doliolida are an order of small marine animals of the subphylum Tunicata. They are in the class Thaliacea, which also includes the salps and pyrosomes. The doliolid body is small, typically 1–2 mm long, and barrel-shaped; it features two wide siphons, one at the front and the other at the back end, and eight or nine circular muscle strands reminiscent of barrel bands. Like all tunicates, except for the predatory tunicate, they are filter feeders. Unlike the related class Ascidiacea, which are sessile, but like the class Appendicularia, they are free-swimming plankton; cilia pump water through the body which drives them forward. As the water passes through, small particles and plankton on which the animal feeds are strained from the water by the gill slits. Doliolids can also move by contracting the muscular bands around the body creating a temporary water jet that thrusts them forward or backward quite quickly. The Doliolida have a complicated life cycle tha ...
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Zooid
A zooid or zoöid is a single animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooids can either be directly connected by tissue (e.g. corals, Catenulida, Siphonophorae, Pyrosome or Ectoprocta) or share a common exoskeleton (e.g. Bryozoa or Pterobranchia). The colonial organism as a whole is called a ''zoon'' , plural ''zoa'' (from Ancient Greek meaning animal; plural , ). Zooids can exhibit polymorphism. For instance, extant bryozoans may have zooids adapted for different functions, such as feeding, anchoring the colony to the substratum and for brooding embryos. However, fossil bryozoans are only known by the colony structures that the zooids formed during life. There are correlations between the size of some zooids and temperature. Variations in zooid size within colonies of fossils can be used as an indicator o ...
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