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? Chordates |
Yellowfin tuna, Thunnus albacares
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| Scientific classification |
| Domain: |
Eukaryota
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| Kingdom: |
Animalia
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| Superphylum: |
Deuterostomia
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| Phylum: |
Chordata
Bateson, 1885 |
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Typical Classes
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- Subphylum Urochordata - Tunicatas
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Ascidiacea
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Thaliacea
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Larvacea
- Subphylum Cephalochordata - Lancelets
- Subphylum Myxini - Hagfishes
- Subphylum Vertebrata - Vertebrates
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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 stage in their life, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a muscular tail extending past the anus. Some scientists argue, however, that the true qualifier should be pharyngeal pouches rather than slits.The phylum Chordata is broken down into three subphyla: Urochordata, Cephalochordata, and Vertebrata. Urochordate larvae have a notochord and a nerve cord but they are lost in adulthood. Cephalochordates have a notochord and a nerve cord but no vertebrae. In vertebrates, the notochord has been replaced by a bony vertebrae.The chordates and two sister phyla, the hemichordates and the echinoderms, make up the deuterostomes, a superphylum.The extant groups of chordates are related as shown in the phylogenetic tree, below. They do not match up very well with the traditional groups, and as a result vertebrate classification is in a state of flux, although their relationships are not very well understood.Chordata
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Urochordata (tunicates)
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Cephalochordata (lancelets)
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Craniata (animals with skulls)
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Myxini or Hyperotreti (hagfish)
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Vertebrata (animals with backbones)
- Cephalaspidomorphi (lampreys)
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Gnathostomata ( jawed vertebrates)
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Chondrichthyes (cartilaginous fish)
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Teleostomi (bony fish, ~ Osteichthyes)
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Actinopterygii (ray-finned fish)
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Sarcopterygii (lobe-finned fish)
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Actinistia ( coelacanths)
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Dipnoi (lungfishes)
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Tetrapoda (four-legged vertebrates)
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Amphibia (amphibians)
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Amniotes (amniotic egg)
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Synapsida
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Reptilia (most modern reptiles)
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