Vascular: relating to the tissues of the body that move blood or nutrient-rich fluids.
This purple urchin moves along the bottom of the aquarium in much the same way it would in the ocean. You can see some of the tube feet attached to the rocks as it pulls itself along. The tube feet are part of the urchin's water vascular system. Urchins can also move using their spines, which are controlled by strong muscles.
CJ Kazilek. (2009, December 23). Movement. ASU - Ask A Biologist. Retrieved April 6, 2020 from https://askabiologist.asu.edu/fr/movement
CJ Kazilek. "Movement". ASU - Ask A Biologist. 23 December, 2009. https://askabiologist.asu.edu/fr/movement
CJ Kazilek. "Movement". ASU - Ask A Biologist. 23 Dec 2009. ASU - Ask A Biologist, Web. 6 Apr 2020. https://askabiologist.asu.edu/fr/movement