Chordates Fossil range: Late Ediacaran – Recent
Yellowfin tuna, Thunnus albacares
Scientific classification
Domain: Eukaryota Kingdom: Animalia Subkingdom: Eumetazoa (unranked) Bilateria Superphylum: Deuterostomia Phylum: Chordata Bateson, 1885
Classes
See below The Ediacaran[5][6]  â€¢  â€¢  | Neoproterozoic (last æon of the Precambrian) Phanerozoic Axis scale: millions of years ago. ... Image File history File links Tuna. ... Binomial name Bonnaterre, 1788 The yellowfin tuna (Thunnus albacares), is a type of tuna eaten by humans as food. ... Scientific classification redirects here. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... For other uses, see Animal (disambiguation). ... subgroups Ctenophora Cnidaria Bilateria Eumetazoa is a clade comprising all major animal groups except sponges. ... Illustration of the different types of symmetry of Life Forms On Earth. ... Phyla Chaetognatha Echinodermata Hemichordata Chordata Deuterostomes (from the Greek: second the mouth) are one of the two superphyla of animals in the taxonomic branch bilateria, the other being the protostomes. ... William Bateson. ... Year 1885 (MDCCCLXXXV) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Tuesday of the 12-day slower Julian calendar). ... A class is the rank in the scientific classification of organisms in biology below Phylum and above Order. ... Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ...

Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. They are united by having, at some time in their life cycle, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail. Some scientists argue that the true qualifier should be pharyngeal pouches rather than slits.^{[citation needed]} For other uses, see phyla. ... For other uses, see Animal (disambiguation). ... This article does not cite any references or sources. ... Invertebrate is an English word that describes any animal without a spinal column. ... The notochord is a flexible, rod-shaped body found in embryos of all chordates. ... The dorsal nerve cord is one of the embryonic features unique to chordates, along with a notochord and pharyngeal slits. ... Pharyngeal slits, found in both hemichordata and chordata, are used by organisms in feeding. ... An endostyle is a longitudinal ciliated groove on the ventral wall of the pharynx which produces mucus to gather food particles. ... A scorpion tail The tail is the section at the rear end of an animals body; in general, the term refers to a distinct, flexible appendage to the torso. ... Pharyngeal or branchial pouches form on the endodermal side between the branchial arches, and pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches. ...

The phylum Chordata is broken down into three subphyla: Urochordata, Cephalochordata, and Vertebrata. Urochordate larvae have a notochord and a nerve cord but these are lost in adulthood. Cephalochordates have a notochord and a nerve cord but no vertebrae. In all vertebrates except for Hagfish, the dorsal hollow nerve cord has been surrounded with cartilaginous or bony vertebrae and the notochord generally reduced. Classes Ascidiacea (2,300 species) Thaliacea Appendicularia Sorberacea Urochordata (sometimes known as tunicata and commonly called urochordates, tunicates, sea squirts) is the subphylum of saclike filter feeders with incurrent and excurrent siphons. ... 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. ... A diagram of a thoracic vertebra. ... For the punk rock band, see Hagfish (band). ... Cartilage is type of dense connective tissue. ...

The chordates and three sister phyla, the hemichordates, the echinoderms and the xenoturbellidae, make up the deuterostomes, a superphylum. It is the largest grouping of deuterostomes. For other uses, see phyla. ... Classes Enterepneusta Pterobranchia Planctosphaeroidea Hemichordata is a phylum of deuterostome animals, generally considered the sister group of our own, the chordates. ... Subphyla & Classes Homalozoa Gill & Caster, 1960 Homostelea Homoiostelea Stylophora † Ctenocystoidea Robison & Sprinkle, 1969 Crinozoa Crinoidea Paracrinoidea † Regnéll, 1945 Cystoidea †von Buch, 1846 Asterozoa Ophiuroidea Asteroidea Echinozoa Echinoidea Holothuroidea Ophiocistioidea Helicoplacoidea † Arkarua † Homalozoa † Pelmatozoa † Edrioasteroidea † Blastozoa † Blastoidea † Eocrinoidea †Jaekel, 1899 † = extinct Echinoderms (Phylum Echinodermata, from the Greek for spiny skin... Species  Westblad, 1949  Israelsson, 1999 Xenoturbella is a genus of bilaterian animals; it is a marine worm. ... Phyla Chaetognatha Echinodermata Hemichordata Chordata Deuterostomes (from the Greek: second the mouth) are one of the two superphyla of animals in the taxonomic branch bilateria, the other being the protostomes. ... A superphylum is a taxon above the phylum and below the subregnum. ...

The extant groups of chordates are related as shown in the phylogenetic tree below. Many of the taxa listed do not match traditional classes because several of those classes are paraphyletic. Different attempts to organize the profusion of chordate clades into a small number of groups, some with and some without paraphyletic taxa, have thrown vertebrate classification into a state of flux. Also, the relationships of some chordate groups are not very well understood. Fig. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... A clade is a term belonging to the discipline of cladistics. ...

Classification

Taxonomy

• Phylum Chordata
  • Subphylum Cephalochordata — (lancelets, 30 species)
  • Subphylum Urochordata or Tunicata — (tunicates, 3,000 species)
    • Class Ascidiacea — (sessile filter-feedeing tunicates)
    • Class Thaliacea — (free-floating tunicates; solitary or colonial)
    • Class Appendicularia — (free-floating tunicates; solitary)
    • Class Sorberacea — (sessile carnivorous tunicates)
  • (Unranked) Craniata (animals with skulls; 57,739 species)
    • Class Myxini or Hyperotreti (hagfish; 65 species)
    • Class Cephalaspidomorphi (Paleozoic jawless fish)
    • Subphylum Vertebrata (vertebrates — animals with backbones; 57,674 species)
      • Infraphylum Agnatha (jawless vertebrates; 100+ species)
        • Class Conodonta (Conodonts)
        • Class Hyperoartia (Lampreys)
        • Class Pteraspidomorphi (Paleozoic jawless fish)
        • Class Thelodonti (Paleozoic jawless fish)
      • Infraphylum Gnathostomata (jawed vertebrates)
        • Class Placodermi (Paleozoic armoured forms)
        • Class Chondrichthyes (cartilaginous fish; 900+ species)
        • (Unranked) Teleostomi
          • Class Acanthodii (Paleozoic "spiny sharks")
          • Superclass Osteichthyes (bony fishes; 30,000+ species)
            • Class Actinopterygii (ray-finned fish; about 30,000 species)
            • Class Sarcopterygii (lobe-finned fish)
          • Superclass Tetrapoda (four-legged vertebrates; 18,000+ species)
            • Class Amphibia (amphibians; 6,000 species)
            • Series Amniota (with amniotic egg)
              • Class Sauropsida — (reptiles; 8,225+ species)
                • Class Aves (birds; 8,800–10,000 species)
              • Class Synapsida (mammal-like "reptiles"; 4,500+ species)
                • Class Mammalia (mammals; 5,800 species)

For the science of classifying living things, see alpha taxonomy. ... Families Asymmetronidae Branchiostomidae The lancelets (subphylum Cephalochordata, and traditionally known as the amphioxus) are a group of primitive chordates. ... Classes Ascidiacea Thaliacea Appendicularia Urochordata (sometimes known as tunicata and commonly called urochordates, tunicates or sea squirts) is the subphylum of saclike filter feeders with input and output siphons. ... 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). ... Classes Hyperotreti Vertebrata Craniata is a type of chordate animal group that contains vertebrates (vertebrata) and hagfish (Hyperotreti). ... Genera Eptatretus Myxine Nemamyxine Neomyxine Notomyxine A hagfish is any of several marine chordates of the class Myxini, also known as Hyperotreti. ... subgroups Osteostraci Galeaspida Pituriaspida Anaspida Hyperoartia (lampreys) Cephalaspidomorphs are a taxon of jawless fishes named for the cephalaspids, which is another name for the osteostracans. ... 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. ... Idealized agnatha. ... Conodont Conodonts are extinct worm-like forms with distinctive conical or multi-denticulate teeth made of apatite (calcium phosphate). ... Subfamilies Geotriinae Mordaciinae Petromyzontinae A lamprey is a jawless fish with a toothed, funnel-like sucking mouth, with which most species bore into the flesh of other fishes to suck their blood. ... Orders Arandaspida Heterostraci Thelodontidae Eriptychiida Astraspida Pteraspidomorphi is an extinct subclass of early jawless fish. ... Subgroupings (unranked, see Turner 1991) Theleodontina Loganiida Katoporida There is much debate over whether the clade of Palaeozoic fish known as the Thelodonti (formerly coelolepids[3]) represent a monophyletic grouping, or disparate stem groups to the major lines of jawless and jawed fish. ... Classes Placodermi Chondrichthyes Acanthodii Osteichthyes Gnathostomata is the group of vertebrates with jaws. ... Human jaw front view Human jaw left view Human jaw top view The jaw is either of the two opposable structures forming, or near the entrance to, the mouth. ... Orders Antiarchi † Arthrodira † Brindabellaspida † Petalichthyida † Phyllolepida † Ptyctodontida † Rhenanida † Acanthothoraci † ?Pseudopetalichthyida † ?Stensioellida † The Placodermi are armoured prehistoric fishes known from fossils dating from the late Silurian to the end of the Devonian Period. ... Subclasses and Orders See text. ... 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... Orders Climatiiformes Ischnacanthiformes Acanthodiformes Acanthodii (sometimes called spiny sharks) is a class of extinct fishes, having features of both bony fish (Osteichthyes) and cartilaginous fish (Chondrichthyes). ... Classes Actinopterygii Sarcopterygii Osteichthyes (IPA: ), also called bony fish, are a taxonomic superclass of fish that includes the ray-finned fish (Actinopterygii) and lobe finned fish (Sarcopterygii). ... Orders See text The Actinopterygii are the ray-finned fish. ... Subclasses Coelacanthimorpha - Coelacanths Dipnoi - Lungfishes Tetrapoda Sarcopterygii is traditionally the class of lobe-finned fishes, consisting of lungfish and coelacanths. ... Classes Synapsida Sauropsida Amphibia A tetrapod (Greek tetrapoda, four-legged) is a vertebrate animal having four feet, legs or leglike appendages. ... For other uses, see Amphibian (disambiguation). ... Extant subgroups Synapsida     Mammalia (mammals) Sauropsida    Anapsida        Testudines (turtles)    Diapsida        Lepidosauria           Squamata (lizards and snakes)           Sphenodontida (tuatara)        Archosauria           Crocodilia (crocodiles and alligators)           Aves (birds) The amniotes are a group of vertebrates, comprising the mammals, birds, and various other groups collectively referred to as reptiles. ... Superclasses Anapsida Eurapsida Diapsida Reptilia was an old kingdom or phylum classification that has since been divided into 4 classes. ... For other uses, see Bird (disambiguation). ... Groups Caseasauria Eupelycosauria    Sphenacodontia       Therapsida          (...mammals) Synapsids (fused arch), formerly known as mammal-like reptiles, are a group of amniotes (reptiles and all their ancestors) that developed one hole in their skull (temporal fenestra) behind each eye, about 320 million years ago (Ma) during the late Carboniferous. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria For the folk-rock band see The Mammals. ...

Phylogeny

Note: Lines show probable evolutionary relationships, including extinct taxa, which are denoted with a dagger, †. Some are invertebrates. Chordata is a phylum. Everyone please stop nitpicking on the use of daggers in theoldnewthing blog! This article does not cite any references or sources. ...

Origins

The origin of chordates is currently unknown. The first clearly-identifiable chordates are reduced fish- or lancelet-like specimens from the Cambrian. Most speculations about their origin fit into one or more of these categories: Families Asymmetronidae Branchiostomidae The lancelets (subphylum Cephalochordata, and traditionally known as the amphioxus) are a group of primitive chordates. ... For other uses, see Cambrian (disambiguation). ...

• A sediment-dwelling worm-like animal that evolved a flatter body and/or fins for swimming.
• A sessile tubular filter-feeder that evolved into a free-swimming animal via usage of fins. (Tunicates, considered a chordate, are sessile filter feeders that have a tadpole-like larvae.)
• A drifting or swimming larva of some other kind of animal that eventually retained its swimming features into adulthood.

The notochord's stiffness in many chordates may have evolved to facilitate the effectiveness of alternating muscle contractions for swimming (in S-shaped movements). In other words, in order to bend the body, a muscle needs a rigid structure to pull against, and notochord at early stage is the main feature. Lack of a stiff body part would merely result in the shorting of the animal during muscle contractions instead of the bending motions needed for swimming. Classes Ascidiacea Thaliacea Appendicularia Urochordata (sometimes known as tunicata and commonly called urochordates, tunicates or sea squirts) is the subphylum of saclike filter feeders with input and output siphons. ...

External links

• Chordate node at Tree Of Life
• Chordate node at NCBI Taxonomy

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Chordata

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Chordata