GENERAL HISTOLOGY

Detailed explanation-1: -The podium is the tube-shaped structure that protrudes from the body and contains longitudinal muscle only. When the muscles around the ampulla contract, they squeeze water from the ampulla into the connected podium, causing the podium to elongate.

Detailed explanation-2: -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-3: -Ampullae (ampulla, sing.) are interior parts of the echinoderm tube feet. They extend into the water vascular cavity. It also refers to the posterior, expanded part of the phoronid body.

Detailed explanation-4: -Ampullae: A pouch or sack-like part of the sea star’s water vascular system that expands and contracts to move water up and down each tube foot. When the sea star wants to create a suction at the end of its tube foot, its ampullae pulls water out of the podia.

Detailed explanation-5: -Protraction of the foot is made possible by the contraction of the ampulla musculature. The fluid within the ampulla cavity is driven into the podium which elongates by reason of the increased pressure within its cavity. During protraction the longitudinal muscles of the foot relax.