Vertebrates have a backbone that provides support for the muscles and protection for the spinal cord. The backbone is actually a series of small bones called vertebrae. They are jointed together and locked with rope-like ligaments to provide a flexible but extremely strong anchor for the back muscles. The spinal cord runs down a channel inside the vertebrae, providing protection from damage. In some primitive fish, such as sharks and rays, the spine is made of a tough rubbery material called cartilage.
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