Vertebrate

Vertebrate

Vertebrates /ˈvɜrtɨbrəts/ are animals that are members of the subphylum Vertebrata /-ɑː/ (chordates with backbones and spinal columns). Vertebrates include the overwhelming majority of the phylum chordata, with currently about 64,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds. Extant vertebrates range in size from the frog species Paedophryne amauensis, at as little as 7.7 mm (0.3 inch), to the blue whale, at up to 33 m (110 ft). Vertebrates make up about 4% of all described animal species; the rest are invertebrates, which lack backbones.

The vertebrates traditionally include the hagfishes, which do not have proper vertebrae, though their closest living relatives, the lampreys, do have vertebrae. Hagfishes 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 the hagfishes 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.