Q What is the system that permits fixation and movement to echinoderms?
The system that permits fixation and movement to substrates in echinoderms is called the ambulacral system. In these animals water enters through a structure called madreporite passes through channels and reaches the ambulacral feet in the undersurface of the body. In the ambulacral region in contact with the substrate there are tube feet emptied and filled by water thus acting as suckers.