A starfish, also known as a sea star, possesses a skeleton made of calcareous ossicles that form a unique structure known as a water vascular system. Instead of a traditional bone skeleton like mammals, starfish have a hard, spiny covering made up of small calcium carbonate plates that provide both protection and support.
This skeleton allows for flexibility and aids in movement, as it is not rigid. The ossicles are connected by a thin layer of tissue and can move slightly, enabling the starfish to adapt to different environments. Additionally, the water vascular system allows for movement through hydraulic pressure, which is how they operate their tube feet. Overall, the skeletal structure of a starfish is quite different from that of creatures with a true bone skeleton, emphasizing their unique place in the marine ecosystem.