Answer
Hydrostatic skeletons are the most primitive type of skeletons. They are composed of fluid-filled cavities that provide limited structure and form. Annelids and hydras have hydrostatic structures, as well as mammals such as elephants.
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Hydrostatic skeletons are the most primitive type of skeletons. They are composed of fluid-filled cavities that provide limited structure and form. Annelids and hydras have hydrostatic structures, as well as mammals such as elephants.