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, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a muscular tail extending past the anus. Some scientists argue that the true qualifier should be pharyngeal pouches rather than slits.[citation needed]
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 all vertebrates except for Hagfish, the dorsal hollow nerve cord has been surrounded with cartilaginous or bony vertebrae and the notochord generally reduced.
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. 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.
2007-03-23 04:23:43
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answer #1
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answered by Curly 4
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Just look in the mirror and you will see a member of the Phylum Chordata. They are animals with backbones.
2007-03-23 11:07:22
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answer #2
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answered by Amphibolite 7
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The phylum chordata refers to animals that have a nerve cord going from their brains down their backs. It doesn't necessarily mean having a spine (animals who do are in the subphylum vertebrata).
2007-03-23 11:11:28
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answer #3
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answered by sarge927 7
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anything wiht a nervous chord. a worm is the only one w/ an.c. but no spine.
2007-03-23 11:10:43
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answer #4
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answered by ♥Rayyhol♥ 4
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