Tunicates
Sea Tulips, Pyura spinifera
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Urochordata Giribet et al., 2000
Classes
Ascidiacea (2,300 species) Thaliacea Appendicularia Sorberacea Download high resolution version (1236x1146, 122 KB)A picture of a colony of sea tulips, taken near Castle Rock, Victoria, Australia. ... Binomial name Pyura spinifera Sea tulips are sessile ascidians that live in coastal waters at depths of up to 80 m (260 feet). ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Typical Classes Subphylum Urochordata - Tunicates Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... A class is the rank in the scientific classification of organisms in biology below Phylum and above Order. ... Orders Aplousobranchia Enterogona Phlebobranchia Pleurogona Stolidobranchia Ascidiacea (commonly known as the ascidians) is an order in the Urochordata subphylum of sac-like marine filter feeders. ... Orders Pyrosomida Salpida Doliolida The Thalicea comprise a class of marine animals within the subphylum Urochordata. ... Families Fritillariidae Kowalevskiidae Oikopleuridae The Appendicularia or Larvacea are a group of free-swimming pelagic urochordates found throughout the worlds oceans. ... Sorberacea are benthic animals and a subgroup of the Tunicata (Urochordata). ...

Urochordata (sometimes known as tunicata and commonly called urochordates, tunicates, sea squirts) is the subphylum of saclike filter feeders with incurrent and excurrent siphons. There are also a few exceptions to this plan, like the predatory Megalodicopia hians, looking something like a cross between a jellyfish and a Venus Flytrap. They are members of the phylum Chordata, which also includes lancelets and all vertebrates including humans. They are now considered as the closest relatives to craniates (i.e. hagfish and vertebrates), having dethroned lancelets from that position.^[1] As with other chordates, tunicates possess a notochord during their early stages of development. In biology, a subphylum is a taxonomic rank intermediate between phylum and superclass. ... Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ... The term siphon is used for a number of biological structures, either because flowing liquids are involved or because the object is shaped like a siphon. ... Predatory tunicates (Megalodicopia hians) are tunicates which live anchored along the deep sea canyon walls and seafloor, waiting for tiny animals to drift or swim into their hood-shaped mouths. ... Bold text For other uses, see Jellyfish (disambiguation). ... For other uses, see Venus Flytrap (disambiguation). ... Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... Typical Classes Subphylum Urochordata - Tunicates Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Families Asymmetronidae Branchiostomidae The lancelets (subphylum Cephalochordata, and traditionally known as the amphioxus) are a group of primitive chordates. ... This article does not cite any references or sources. ... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Subphyla Hyperotreti Vertebrata Craniata is an unranked group of chordate animals that contains the vertebrates (subphylum Vertebrata) and hagfish (Myxini), which are sometimes grouped under Vertebrata. ... Genera Eptatretus Myxine Nemamyxine Neomyxine Notomyxine Paramyxine Quadratus This article is about the Hagfish. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... Families Asymmetronidae Branchiostomidae The lancelets (subphylum Cephalochordata, and traditionally known as the amphioxus) are a group of primitive chordates. ... Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... The notochord is a flexible, rod-shaped body found in embryos of all chordates. ...

They lack segmentation, even in the tail. Metanephridia are absent. The original coelom is degenerated to a pericardial cavity and gonads. Except for the pharynx, heart and gonads, the organs are enclosed in a membrane called an epicardium, which is surrounded by a jelly-like matrix known as mesenchyme. The motile larval stages may have the appearance of a tadpole, whereas the adult stage has a barrel-like, sedentary form. They feed by filtering sea water through pharyngeal slits. Metanephridium (pl. ... By the broadest definition, a body cavity is any fluid filled space in a multicellular organism. ... The pericardium is a double-walled sac that contains the heart and the roots of the great vessels. ... A sex organ, or primary sexual characteristic, narrowly defined, is any of those parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction and constitute the reproductive system in an complex organism; namely: Male: penis (notably the glans penis... The pharynx (plural: pharynges) is the part of the neck and throat situated immediately posterior to the mouth and nasal cavity, and cranial, or superior, to the esophagus, larynx, and trachea. ... A larval insect A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... Tadpole of Littlejohns Tree Frog (Litoria littlejohni) A tadpole (also known as a pollywog or polliwog) is a larval amphibian, the juvenile form of a frog, toad, newt, salamander, or caecilian. ...

Description

Most tunicates are hermaphroditic. The eggs are kept inside their body until they hatch, while sperm is released into the water where it fertilizes other individuals when brought in with incoming water. The 1st-century BC sculpture The Reclining Hermaphrodite, in the Museo Nazionale Romano, Palazzo Massimo Alle Terme in Rome A hermaphrodite is an organism that possesses both male and female sex organs during its life. ...

Tunicates are suspension feeders. They have two openings in their body cavity: an incurrent and an excurrent siphon. The incurrent siphon is used to intake food and water and the excurrent siphon expels waste and water. The tunicate's primary food source is plankton. Plankton gets entangled in the mucus secreted from the endostyle. The tunicate's pharynx is covered by miniature hairs called ciliated cells which allow the consumed plankton to pass down through to the esophagus. Their guts are U-shaped, and their anuses empty directly to the outside environment. Tunicates are also the only animals able to create cellulose. For the SpongeBob SquarePants character, see Sheldon J. Plankton. ... An endostyle is a longitudinal ciliated groove on the ventral wall of the pharynx which produces mucus to gather food particles. ... The pharynx (plural: pharynges) is the part of the neck and throat situated immediately posterior to the mouth and nasal cavity, and cranial, or superior, to the esophagus, larynx, and trachea. ... The esophagus (also spelled oesophagus/œsophagus, Greek ), or gullet is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ...

Some larval forms appear very much like primitive chordates or hemichordates with a notochord (primitive spinal cord). Superficially the larva resemble small tadpoles. Some forms have a calcereous spicule that may be preserved as a fossil. They have appeared from the Jurassic to the present, with one proposed Neoproterozoic form, Yarnemia. Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... The notochord is a flexible, rod-shaped body found in embryos of all chordates. ... The Spinal cord nested in the vertebral column. ... Tadpole of Littlejohns Tree Frog (Litoria littlejohni) A tadpole (also known as a pollywog or polliwog) is a larval amphibian, the juvenile form of a frog, toad, newt, salamander, or caecilian. ... Spicules Spicules are skeletal structures that occur in most sponges. ... The Jurassic Period is a major unit of the geologic timescale that extends from about 199. ... The Neoproterozoic Era is the unit of geologic time from 1,000 to 542 +/- 0. ... Yarnemia is a fossil dubiously classified in the urochordata family. ...

The larval stage ends when the tunicate finds a suitable rock to affix to and cements itself in place. The larval form is not capable of feeding, and is only a dispersal mechanism. Many physical changes occur to the tunicate's body, one of the most interesting being the digestion of the cerebral ganglion previously used to control movement. From this comes the common saying that the sea squirt "eats its own brain".^[2]

Since the larval form has a nervous system and is capable of active locomotion as opposed to the adult form which seems more primitive in comparison, it perhaps offers a real life example of the famous quote of Samuel Butler that "the hen is an egg's way of producing another egg". Here, the egg is analogous to the adult form, and the hen to the larval form. Samuel Butler is the name of several notable persons: Samuel Butler (1612-1680), author of Hudibras Samuel Butler (1774-1839), classical scholar Samuel Butler (1835-1902), grandson of the scholar, author of Erewhon This is a disambiguation page — a navigational aid which lists other pages that might otherwise share...

Once grown, adults can develop a thick covering, called a tunic, to protect their barrel-shaped bodies from enemies.

Sea squirts are more closely related to fish, birds, and people than worms, sea stars, or other invertebrates.

In some classes, the adults remain pelagic (swimming or drifting in the open sea), although their larvae undergo similar metamorphoses to a higher or lower degree.

Tunicate blood is particularly interesting. It contains high concentrations of the rare metal vanadium and vanadium-associated proteins. Some Tunicates can concentrate vanadium up to a level one million times that of the surrounding seawater. It is still unknown how they do this or why. Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... General Name, symbol, number vanadium, V, 23 Chemical series transition metals Group, period, block 5, 4, d Appearance silver-grey metal Standard atomic weight 50. ... Vanabins (also known as vanadium-associated proteins or vanadium chromagen) are a class of metalloproteins containing vanadium. ...

The Tunicata contains about 3,000 species, usually divided into the following classes.

• Ascidiacea, (Aplousobranchia, Phlebobranchia, and Stolidobranchia)
• Thaliacea
• Appendicularia (Larvacea)
• Sorberacea.

Newer evidence indicates that the Ascidiacea is an artificial group. The new classification would then look like this. Orders Aplousobranchia Enterogona Phlebobranchia Pleurogona Stolidobranchia Ascidiacea (commonly known as the ascidians) is an order in the Urochordata subphylum of sac-like marine filter feeders. ... Orders Pyrosomida Salpida Doliolida The Thalicea comprise a class of marine animals within the subphylum Urochordata. ... Families Fritillariidae Kowalevskiidae Oikopleuridae The Appendicularia or Larvacea are a group of free-swimming pelagic urochordates found throughout the worlds oceans. ... Families Fritillariidae Kowalevskiidae Oikopleuridae The Appendicularia or Larvacea are a group of free-swimming pelagic urochordates found throughout the worlds oceans. ... Sorberacea are benthic animals and a subgroup of the Tunicata (Urochordata). ...

• Stolidobranchia,
• Phlebobranchia and Thaliacea,
• Aplousobranchia and Appendicularia,
• Sorberacea would belong somewhere in Ascidiacea, or be in a taxon on its own.

For the moment, the traditional classification is followed.

A species that has attracted interest in biology is Ciona intestinalis which is used for developmental studies. Binomial name Ciona intestinalis (Linnaeus, 1767) Ciona intestinalis is a Urochordata (sea squirt) whose genome has been sequenced. ...

Invasive species

Over the past few years, urochordates (notably of the genera Didemnum and Styela) have been invading coastal waters in many countries, and are spreading quickly. These mat-like organisms can smother other sea life, have very few natural predators, and are causing much concern.^[3] Transportation of invasive tunicates is usually in the ballast water or on the hulls of ships. Current research indicates that many tunicates previously thought to be indigenous to Europe and the Americas are, in fact, invaders. Some of these invasions may have occurred centuries or even millennia ago. In some areas, tunicates are proving to be a major nuisance in aquaculture operations.^[4][5] Didemnum is a genus of tunicates in the family Didemnidae. ... Suborders and families Suborder Stolidobranchia Family Styelidae Genus Styela Family Botryllidae Genus Botrylloides Genus Botryllus Pleurogona is an order of tunicates. ... Lantana invasion of abandoned citrus plantation; Moshav Sdey Hemed, Israel The term invasive species refers to a subset of introduced species or non-indigenous species that are rapidly expanding outside of their native range. ... For other uses, see Ship (disambiguation). ... Workers harvest catfish from the Delta Pride Catfish farms in Mississippi Aquaculture is the cultivation of aquatic organisms. ...

Chemical derivatives

Tunicates have been found to contain a host of potentially significant compounds, among which are:

• Didemnins (effective against various types of cancer, antivirals, immunosuppressants)
• Aplidine (effective against various types of cancer)
• Esteinascidin 743 (effective against various types of cancer)

Structure of Didemnins A-C Didemnins are cyclodepsipeptide compounds isolated from a tunicate (sea-squirt) of the genus Trididemnum (family of Didemnidæ) that were collected in the Caribbean Sea. ... Aplidine is a compound found in tunicates which shows promise in shrinking tumors in pancreatic, stomach, bladder, and prostate cancers. ... Esteinascidin 743 is a derivative of tunicates which has been found to be useful in the treatment of skin, breast, and lung cancers[1]. ^ Garrison, Tom. ...

Regenerative Medicine

In the May 2007 issue of The FASEB Journal, researchers from Stanford University show that the tunicate can correct abnormalities over a series of generations, and they suggest that a similar regenerative process might be possible for humans. Ayelet Voskoboynik of Stanford University and author of the study says "We hope the mechanisms underlying this phenomenon will ultimately lead to new insights regarding the potential of cells and tissues to be reprogrammed and regenerate compromised organs in humans." Gerald Weissman, editor-in-chief of The FASEB Journal, said "This study is a landmark in regenerative medicine; the Stanford group has accomplished the biological equivalent of turning a sow's ear into a silk purse and back again."^[6]

References

Wikispecies has information related to:

Urochordata

• Dennis. 2003. pers. comm. Marine Science Dept. Orange Coast College.
• Solomon, E., L. Berg, D. Martin. 2002. Biology. Brooks/Cole.

1. ^ Error in the Genealogy of Human
2. ^ Brainless Fish in Topless Bar - Fast Company
3. ^ Squirt Alert
4. ^ Marine Nuisance Species
5. ^ Woods Hole Oceanographic Institution
6. ^ Sea Squirt, Heal Thyself: Scientists Make Major Breakthrough In Regenerative Medicine

Image File history File links Wikispecies-logo. ... Wikispecies is a wiki-based online project supported by the Wikimedia Foundation that aims to create a comprehensive free content catalogue of all species (including animalia, plantae, fungi, bacteria, archaea, and protista). ...

External links

• Error in the Genealogy of Human
• washington.edu page on tunicates ^{[dead link]}
• Ascidians.com has pictures of species around the world
• Squirt Alert: Science News Online, [December 24], [2005]
• Ode to the Cunji, in Macquarie University Biology Bytes June 1998