What are the differences between the various support systems found in animals?The hydroskeleton is formed by inner liquids (as in earthworms); the dermoskeleton is found under the skin and muscle tissue (as in starfish); the exoskeleon is an external skeleton, which acts like armour (as in insects and crustaceans); the endoskeleton is internal, as in the human body. Vertebrates have an endoskeleton with a flexible spine that runs the whole length of the animal’s back. Invertebrates don’t.