Organisms in the subphylum of Vertebrata, fishes, reptiles, amphibians, birds, and mammals, all share a vertebral column, as well as all the typical features that all organisms within the chordata phylum share. The vertebral column surrounds and more or less replaces the notochord as the chief "stiffener" of the body in locomotion. There are over 64,000 species in Vertebrata, and take up a majority of the Chordata phylum.