Question

Which one of the following is not part of water vascular system of starfish?

• A. Stone canal
• B. Madreporite
• C. Circular canal and tube feet
• D. Osphradium

Answer 1

The correct option is D Osphradium

Starfish belongs to the group of echinoderm. Echinoderm has a unique vascular water system. This system opens to the exterior through a sieve-like madreporite on the aboral surface of the animal. The madreporite is linked to a slender duct called the stone canal. This canal extends to a ring canal that encircles the mouth or oesophagus. From this, radial canals extend along the arms. Short lateral canals branch off the radial canals, each one ending in an ampulla. Part of the ampulla can protrude through a pore to the exterior and is known as a podium or tube feet. Osphradium is an olfactory organ present in certain molluscs.
Therefore, the correct answer is option D.