Category:Vertebrates

Vertebrates  (chordates with backbones) are all species of animals within the subphylum Vertebrata. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates include such groups as the following: Extant vertebrates range in size from the Amau frog (Paedophryne amauensis), at as little as 7.7 mm (0.30 in), to the blue whale (Balaenoptera musculus) at up to 33 m (108 ft). Vertebrates make up less than 5% of all described animal species; the rest are invertebrates, which lack vertebral columns.
 * jawless fishes
 * jawed vertebrates, which include cartilaginous fish (sharks, rays, and ratfish)
 * tetrapods, which include amphibians, reptiles, birds, and mammals
 * bony fish

The vertebrates traditionally include the hagfish, which do not have proper vertebrae due to their loss in evolution, though their closest living relatives, the lampreys, do. 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, and so also are vertebrates in a monophyletic sense. Others consider them a sister group of vertebrates in the common taxon of craniata.