In chordate animals notochord, dorsal tubular nerve cord and pharyngeal slits are present.
In Amphioxus notochord is a cylindrical rod extending the whole length of the body from anterior end to posterior end. it is present below the dorsal nerve cord and above the alimentary canal. The notochord is formed b vacuolated cells. They are filled with fluid. These turgid cells will give strength to the notochord. This notochord is covered by a sheath of connective tissue.