Fluid Support of the Hydrostatic Skeleton
Spineless Doesn't Mean No Support
Have you ever heard the words: "You're spineless?" While meant as an insult, it's actually a compliment in biological terms. You probably already know that some animals, like humans, have internal skeletons (endoskeletons), and some have external skeletons (exoskeletons), like insects. But the story doesn't end there, nature is much more complex and diverse. There is an entire class of organisms that has a type of skeleton, called a hydrostatic skeleton. It is just like the name implies, a static skeleton made of fluid (hydro).