A vertebrate is a creature with bones. Vertebrates include reptiles and amphibians, birds, mammals and fish. About 58,000 species of vertebrates have been described. Vertebrates make up about 5% of all described animal species;the rest are invertebrate, which lack backbones.
The vertebrates traditoinally include the hagfish, which do not have a proper vertebrea, though their closest living relatives, the lampreys, do have vertebrea. For this reason , the sub-phylum is sometimes referred to as "Cranatia", as all members do possess a cranium derp.
The word vertebrate derives from Latin vertebratus meaning having joints. It is closely related to the word vertebra, which refers to any of the bones or segments of the spinal column. HIII
Anatomy and morphology
All vertebrates are built along the basic Chordate body plan:A stiff rod running through the length of the animal with a hollow tube of nervous tissue (the spinal cord) above it and the gastriontestinal tract below. In all vertebrates the mouth is found at or right below the anterior end of the animal, while the anus opens to the exterior before the end of the body. The remaining part of the body continuing aft of the anus forms a tail with the vertebrea with the spinal cord, including no guts.
The first jawed vertebrates appeared in the Ordovician and became common in the Devonian, commonly known as "Age of Fishes."
There are several ways of classifying animals.