A vertebrate is an animal with a backbone. In this example, vertebrates are classified based on series of visible characteristics. If it has fur then it is classified as a mammal else they are grouped based on feathers. If it has feathers then it is classified as a bird else they are grouped based on dry skin. If it has dry skin then it is classified as a Reptile else divide the group based on scales. If it has scales it is classified under fishes else classified under Amphibians.