Having a backbone is a phrase that is used to describe someone who is brave and stands up for what they believe in. A VERTEBRATE is an animal with a backbone, which includes mammals, birds, reptiles, amphibians, and fish. This term is used to describe animals that have a spine or backbone, which is made up of a series of bones called vertebrae. The vertebrae provide support and protection for the spinal cord, which is responsible for transmitting signals from the brain to the rest of the body.