Basis of as well as locomotion employed by .

Associated with the water are the tube feet of members of phylum Echinodermata. The system is literally a series of tubes found throughout the animals through which water can moved in a manner and to an extent that is controlled by the animal.

A water vascular system can be compared with both and open circulatory systems. Indeed, a progression can be made with closed circulatory systems keeping the fluid flowing throughout the organism within the animal and more or less in , the open circulation system keeping the fluid flowing within the animal, and the water vascular system keeping the fluid flowing but not completely within the animal.