Do all vertebrates have endoskeletons?

An endoskeleton is a skeleton that is on the inside of a body. The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage). read more

*They all have endoskeletons that are formed of bone or cartilage. *They have brains protected by craniums (skulls). *They have closed circulatory systems in which the walls of the heart are continiuous with the blood vessels. read more

Like all chordates, vertebrates have a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. The 50,000 species of living vertebrates are placed in nine classes: hagfish, lampreys, cartilaginous fish, ray-finned fish, lobe-finned fish, amphibians, reptiles, birds, and mammals. read more