Phylum Echinodermata, meaning spiny skin in Greek, consists of organisms usually identified by their five point symmetry, such as starfish, sea urchins, sea dollars, and sea cucumbers. There are about 7000 known species and about 1300 that have been extinct. This is the largest phylum without any freshwater and terrestrial forms. They are mostly all found in the ocean. They don’t have a full muscular system and movement is mainly based on their vascular system.
Regarding muscular movement, echinoderms have tube feet that have suction disks at the bottom that helps them to crawl and attach themselves to objects. They also have a water vascular system that serves for movement which is a network of hydraulic canals that branch into their tubed feet that function in locomotion, feeding, and gas exchange.