Chordates (Phylum Chordata)
During their embryonic development, all chordates pass through a stage called the pharyngula [View] with these features: ...
Chordates
Lancelet Branchiostoma lanceolatum
Zebrafish Danio rerio
Frogs Xenopus laevis
Chicken Gallus gallus
Mouse Mus musculus (Mammalian embryogenesis) ...
Chordates have a dorsal rather than ventral nervous system. Several evolutionary trends occur in chordates: spinal cord, continuation of cephalization in the form of larger and more complex brains, and development of a more elaborate nervous system.
chordates Animals that display a hollow dorsal nerve cord, gill slits, and a notochord. Includes the protochordates and the vertebrates.
Hemichordates are classified into three classes, two with living members, one consisting of only fossil forms. The Enteropneusta includes the acorn worms; the Pterobranchia includes 20 species of colonial bottom dwelling worms.
It grows fast, reproduces weekly, and thus, a good model for genetic studies of protochordates.
All chordates also have (2) a notochord which is a flexible, rod like structure, dorsal to (above) the digestive tract which provides internal support for the body.
Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. About 57,739 species of vertebrates have been described[citation needed].
pharyngeal slits -- Characteristic of chordates, pharyngeal slits are openings through which water is taken into the pharynx, or throat.
Ancient chordates-forerunners of fish, of frogs, of chickens, of humans-had a single Hox cluster with probably thirteen genes in them.
deuterostomes - broad classification of triploblastic animals including echinoderms and chordates that tend to share certain embryological traits; among these the formation of the "mouth second" (hence the name) during gastrulation, ...
deuterostome
An evolutionary line of coelomates (ex. echinoderms and chordates) that are characterized by radial, indeterminate cleavage and development of the anus from the blastopore.
One of two distinct evolutionary lines of coelomates, consisting of the echinoderms and chordates and characterized by radial, indeterminate cleavage, enterocoelous formation of the coelom, and development of the anus from the blastopore.
A group of Metazoans that exhibit indeterminate, radial cleavage and that develop a mouth independent of, and at some distance from, the blastopore. (Echinoderms and Chordates and related minor phyla).
 See also: Organ, Plant, Animal, Animals, Chordate
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