A clam does not contain any bones so the only thing that the skeletal system contains is its shell. It's shell contains two valves that the clam uses for protection and muscles attachment. This makes for a very simple system.

The skeletal system of a frog is much more complex than that of a clam. Since the frog is a vertebrate it contains a backbone. The skeletal system can be broken up into two different parts: an axial skeleton and an appendicular skeleton. The axial skeleton contains the skull, vertebrae and sternum. Th appendicular skeleton contains the pectoral, pelvic, and limb bones.

The SKELETAL System