water-vascular system

The water-vascular system is a unique hydraulic system found in echinoderms, such as starfishes and sea urchins. This system is crucial for locomotion, respiration, and feeding. It consists of a network of fluid-filled canals lined with ciliated epithelium, which are derived from the coelom.1

Key components include:
* Madreporite: A porous plate that connects the system to the outside environment.1
* Ring canal: A circular canal surrounding the mouth.1
* Radial canals: Canals that extend into each arm of the animal.1
* Tube feet (podia): Small, muscular sacs that extend from the radial canals and are used for movement and attachment.12

When the sacs contract, fluid is pushed into the tube feet, causing them to elongate and adhere to surfaces. This system allows echinoderms to move, capture prey, and exchange gases with their environment.1