What is notochord , on the basis of notochord described two major grou

1.	What is notochord , on the basis of notochord described two major groups of animals?
Answer» A notochord is a primitive beginning to the backbone. It appears in embryos as a small flexible rod made from cells from the mesoderm, which is one of the three layers of cells of embryos.\xa0On the Basis of Absence and Presence of Notochord:\xa0The notochord in majority of chordates is subsequently replaced by vertebral columns, which are known as vertebrates. In the case of small number of chordates, the notochord is not being replaced by vertebral column rather notochord remains as a notochord, and they are regarded as protochordates. But in non-cordates, notochord and vertebral column both are absent.

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