GENERAL HISTOLOGY

Detailed explanation-1: -Each tube foot consists of two parts: the ampulla and the podium. The ampulla is a water-filled sac contained in the body of the animal that contains both circular muscles and longitudinal muscle. The podium is the tube-shaped structure that protrudes from the body and contains longitudinal muscle only.

Detailed explanation-2: -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.

Detailed explanation-3: -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-4: -Ampulla in Echinoderm Definition The organisms in this phylum contain tube feet which have a part called ampulla that is used for locomotion. The ampulla functions to stretch the tube feet and thereby help in the locomotion.