. An endoskeleon is an internal skeleton built of bone or cartilage. Bone and cartilage are both dense connective tissues. Each tissue is made of collagen fibers that are embedded in a matrix, or combination, of harder materials. Endoskeleton has four parts that Braincase, Vertebrae, Bones, Gill arches.
1)Braincase: A braincase or cranium protects the brain. 2)Vertebrae: A series of short, stiff vertebrae are separated by joints. This internal backbone protects the spinal cord. It also replaces the notochord with harder material that can resist forces produced by large muscles. Joints between the vertebrae let the backbone bends as the animal moves. 3) Bones: Bones support and protect the body's soft tissues and provides points for muscle attachment. 4) Gill arches: Gill arches, found in the pharynx of fish and some amphibians, support the gills. Jiaqi Li 02:34, 10 April 2016 (UTC)Jiaqi LI