What are the similarities and differences between an exoskeleton a hydro-skeleton and internal skeleton?

Exoskeletons, hydro-skeletons, and internal skeletons are all structural systems that provide support and shape to organisms. Exoskeletons, like those found in insects and crustaceans, are rigid outer structures made of chitin or calcium carbonate. Hydro-skeletons, seen in organisms like jellyfish, rely on fluid pressure within a cavity to maintain shape and support movement. Internal skeletons, or endoskeletons, such as those in vertebrates, are internal structures made of bone or cartilage that provide support while allowing for growth and flexibility.