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A chordate (/ ˈ k ɔːr d eɪ t / KOR-dayt) is a deuterostomal bilaterian animal belonging to the phylum Chordata (/ k ɔːr ˈ d eɪ t ə / kor-DAY-tə).All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics (synapomorphies) that distinguish them from other taxa.
It is easy to care for in the laboratory and a protocol has been developed which can yield large numbers of embryos on a daily basis. [35] There is a remarkable degree of similarity in the gene sequence conservation and complexity between the sea anemone and vertebrates. [35]
A large difference between vertebrates and invertebrates is the location and layering of HOX genes. The fundamental mechanisms of development are strongly conserved among vertebrates from fish to mammals. Due to the fact that the HOX genes are so highly conserved, most research has been done on much simpler model organisms, such as mice.
Segmentation in animals typically falls into three types, characteristic of different arthropods, vertebrates, and annelids. Arthropods such as the fruit fly form segments from a field of equivalent cells based on transcription factor gradients. Vertebrates like the zebrafish use oscillating gene expression to define segments known as somites.
Vertebrates share these characteristics with other chordates. [4] Vertebrates are distinguished from all other animals, including other chordates, by multiple synapomorphies, namely the vertebral column; skull of bone or cartilage, large brain divided into 3 or more sections, a muscular heart with multiple chambers; an inner ear with ...
On the other hand, fossils of early chordates are very rare, as non-vertebrate chordates have no bone tissue or teeth, and fossils of no Post-Cambrian non-vertebrate chordates are known aside from the Permian-aged Paleobranchiostoma, trace fossils of the Ordovician colonial tunicate Catellocaula, and various Jurassic-aged and Tertiary-aged ...
According to this theory, there is a deep agreement between the vertebrates and cephalochordates, and even all chordates. [75] [76] With the advent of molecular genetics lancelets are once again regarded as a model of vertebrate ancestors, and are used again as a model organism. [77] [30]
It is easy to care for in the laboratory and a protocol has been developed which can yield large numbers of embryos on a daily basis. [235] There is a remarkable degree of similarity in the gene sequence conservation and complexity between the sea anemone and vertebrates. [235]