How does a hydrostatic skeleton provide support?

Hydrostatic refers to a skeleton that supports a frame using water pressure; imagine a balloon filled with water. The water is held within a body cavity called the coelom. This skeleton is considered an endoskeleton, or a skeleton the inside of the body. Arthropods, like insects and crustaceans have an external skeleton, or exoskeleton.

A hydrostatic skeleton is found on soft bodied animals such as mollusks, cephalopods, and echinoderms.

Jellyfish also have hydrostatic skeletons.