Question

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

• A. Tube feet
• B. Polian vesicle
• C. Tiedemann's body
• D. Axial sinus

Answer 1

The correct option is D Axial sinus

In case of echinoderms, there is a water vascular system. This system plays an important role in movement, nutrient transport and respiration. The water vascular system is a part of the coelom. The system consists of many organs and structures like the madreporite, stone canal, ring canal and the radial canal. Tiedemann's body, lateral canals and tube feet are also associated with the this water vascular system.

Axial sinus is the part of perihaemal system. This is the walled tube which surrounds the stone canal. This is not involved in the system and thus, not a part of water vascular system. It is also derived from coelom.

Thus, the correct answer is option D.