For 10 points, name this set of structures involved in respiration and locomotion in echinoderms.
The purpose of one feature in this entity was the subject of experiments by Dakin and Fechter. Colacino found that only 70% of the oxygen transported by this entity was bound to hemoglobin in S. briareus. Accessory structures to it include Tiedemann's bodies, which produce coelomocytes. Both circular and longitudinal muscle are found in the ampullae, which lie proximal to this set of structures in one organism. Ophiuroids contain a slightly unorthodox version of this set of structures. Several ring canals in this set of structures surround a stone canal, the entrance to which is controlled by the madreporite. Hydraulic pressure is used to move food into this set of structures through the tube feet. For 10 points, name this set of structures involved in respiration and locomotion in echinoderms.
The purpose of one feature in this entity was the subject of experiments by Dakin and Fechter.
water vascular system