UNIT 2  ANIMALS: VERTEBRATES
Animals with backbones are called vertebrates. They include the most highly developed animals—fishes, amphibians, reptiles, birds, and mammals—among which are human beings, the highest of the primates.

 

The bones of the body form a framework called the skeleton. This framework supports and protects the softer tissues. All the higher animals have an internal skeleton (endoskeleton) with a central spine, or backbone.