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Chordonia

(Infrakingdom)

Overview

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A taxonomic infrakingdom.

Photos

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Taxonomy

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The Infrakingdom Chordonia is a member of the Branch Deuterostomia. Here is the complete "parentage" of Chordonia:

The Infrakingdom Chordonia is further organized into finer groupings including:

Phyla

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Chordata

Chordates ( 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. The phylum Chordata consists of three subphyla: Urochordata, represented by tunicates; Cephalochordata, represented by lancelets; and Craniata, which includes Vertebrata. The Hemichordata have been presented as a fourth chordate subphylum, but they are now usually treated as a separate phylum. 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 brain or specialist sense organs, and a very simple circulatory system. Craniates are the only sub-phylum whose members have skulls. In all craniates except for Hagfish, the dorsal hollow nerve cord has been surrounded with cartilaginous or bony vertebrae and the notochord generally reduced; hence hagfish are not regarded as vertebrates. The chordates and three sister phyla, the Hemichordata, the Echinodermata and the Xenoturbellida, make up the deuterostomes, one of the two superphyla that encompass all fairly complex animals. [more]

At least 179,766 species and subspecies belong to the Phylum Chordata.

More info about the Phylum Chordata may be found here.

Sources

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Last Revised: September 22, 2009
2009/09/22 05:50:17