Vertebrate topic

Vertebrates are members of the subphylum Vertebrata, chordates with backbone or spinal column. The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lamprey, which do have vertebrae. For this reason, the sub-phylum is sometimes referred to as "Craniata", as all members do possess a cranium. About 58,000 species of vertebrates have been described. Vertebrata is the largest subphylum of chordates, and contains many familiar groups of... full article at wikipedia