GENERAL HISTOLOGY

Detailed explanation-1: -Complete answer: The water vascular system is found in the phylum Echinodermata . The water vascular system is a hydraulic system that is used for locomotion, respiration, and food and waste transportation. It has canals which are connected to numerous tube feet to push the organisms against the ground.

Detailed explanation-2: -An echinoderm moves by using many tube feet. Tube feet are small, delicate projections attached along the side of a water-filled tube called a radial canal.

Detailed explanation-3: -Echinoderms have a spiny endoskeleton. They have radial symmetry as adults but bilateral symmetry as larvae. Echinoderms have a unique water vascular system with tube feet.

Detailed explanation-4: -Water vascular system performs various functions such as locomotion, capture and transport of food and respiration. During respiration, tube feet serve equivalent to the gills. Hence, the correct answer is option A.

Detailed explanation-5: -Because sea urchins have no arms, the five radial canals simply run along the inside of the solid skeletal “test", arching upwards towards the anus. The ampullae branching off from either side of the radial canals give rise to ten rows of tube feet, which penetrate through holes in the test to the outside.