Category:Vertebrate

Vertebrates /ˈvɜːrtəˌbrəts/ comprise all species of animals within the subphylum Vertebrata /-ə/ (chordates with backbones). Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described.[4] Vertebrates include such groups as the following: Extant vertebrates range in size from the frog species Paedophryne amauensis, at as little as 7.7 mm (0.30 in), to the blue whale, at up to 33 m (108 ft). Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns.
 * jawless fishes
 * jawed vertebrates, which include the cartilaginous fishes (sharks, rays, and ratfish)
 * tetrapods, which include amphibians, reptiles, birds and mammals
 * bony fishes

The vertebrates traditionally include the hagfish, which do not have proper vertebrae due to their loss in evolution,[5] though their closest living relatives, the lampreys, do.[6] Hagfish do, however, possess a cranium. For this reason, the vertebrate subphylum is sometimes referred to as "Craniata" when discussing morphology.

Molecular analysis since 1992 has suggested that hagfish are most closely related to lampreys,[7] and so also are vertebrates in a monophyletic sense. Others consider them a sister group of vertebrates in the common taxon of craniata.[8]