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 Chordata - Definition 


Chordates
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Typical Classes

Chordates (phylum Chordata) include 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 and a tail extending past the anus.

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 In vertebrates, the notochord has been replaced by a bony vertebral column.

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 very well understood.

Chordata



ca:Cordat da:Chordater de:Chordatiere et:Keelikloomad es:Cordado eo:Ĥordulo fr:Cord fy:Rchstringdier ia:Chordatos it:Cordati he:מיתרניים ko:척색동물문 jbo:Skoselti'e nl:Chordata ja:脊索動物 oc:Chordata pl:Strunowce pt:Cordado ru:Хордовые fi:Selkjnteiset sv:Ryggstrngsdjur uk:Хордові zh:脊索动物

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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Chordata".