GENERAL HISTOLOGY

Detailed explanation-1: -The ring canal connects the radial canals (there are five in a pentaradial animal), and the radial canals move water into the ampullae, which have tube feet through which the water moves.

Detailed explanation-2: -Water gets from the madreporite to the tube feet through the radial canal. Valves keep water from flowing back into the radial canal (Fig. 3.84).

Detailed explanation-3: -The lateral canals branch from the radial canal and bring the water into the ampullae and podia of the tube feet. The tube feet extend between the endoskeletal plates to reach outside of the organism.

Detailed explanation-4: -each arm, the radial canal gives out two series of short, narrow, transverse branches called lateral or podial canals. Each lateral canal is attached to the base of a tube foot and its provided with a valve to prevent backward flow of fluid into the radial canal.