GENERAL HISTOLOGY

Detailed explanation-1: -The lateral canals branch from the radial canal and bring the water into the ampullae and podia of the tube feet.

Detailed explanation-2: -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-3: -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-4: -The radial canals carry water to the ampullae and provide suction to the tube feet. The tube feet latch on to surfaces and move in a wave, with one body section attaching to the surfaces as another releases. Most sea stars cannot move quickly.

Detailed explanation-5: -The radial canals in crinoids run along each arm into an ambulcral groove and tube feet. The ambulacral groove with its many cilia and hydraulically driven tube feet manipulate captured food down the ambulacral grooves along the arms down to the mouth, situated at the tegmen which is positioned at the base of the arms.