Vertebrate species are animals with backbones or spinal columns. Example species include: bony fish; sharks; rays; amphibians; reptiles; mammals; and birds. In some cases closely related species lacking a backbone such as hagfish with a bony skull called a cranium are included in the group. To date this group includes as many as 58,000 species ranging in size from a small carp of 0.3 inches to 110 feet for the Blue Whale.