What is an hydrostatic animal?

A hydrostatic animal is one that relies on the pressure of fluid within its body to maintain its shape and support its structure. This type of organism typically has a body filled with a fluid-filled cavity, known as a coelom or hydrostatic skeleton, which enables movement and provides rigidity. Common examples include jellyfish, worms, and certain mollusks, which use this internal fluid pressure to facilitate locomotion and other bodily functions.