Question

The locomotory organs of echinodermata are____________
A. Tube feet
B. Muscular feet
C. Jointed legs
D. Parapodia

Answer 1

Hint:
The unique feature of echinoderms is the water vascular system.
 It is the complex system of the water containing tubes and the bladders which pass through the pores in the skeleton.

Complete answer:
- The members of phylum Echinodermata walk with the help of tube feet.
- Water vascular system of echinodermata helps in locomotion and in the movement of the organisms.
The tube feet are small tube-like projections on the oral side of the echinoderms. These tube feet are used for the locomotion, exchange of gases and for feeding.

Therefore, the correct answer is option A.

Additional information:
- Tube feets are locomotory organs of the echinoderms.
- They are marine animals with spiny skin.
- They have an exoskeleton of the calcareous plates from which the spine arises.
- Adults are radially symmetrical, while the larvae are bilaterally symmetrical in nature.
- Most echinoderms are sessile as they live in the groups, while others are solitary.
- A very unique feature of the echinoderms is the water vascular system.
- It is the complex system of water containing tubes and bladders which pass through pores in the skeleton.
- The echinoderms reproduce sexually and the sexes take place separately.
- Some of the echinoderms like starfish and the brittle stars have arms arising from the central disc.

Note:
> The vascular system runs through each arm, carrying seawater to the tube feet and causing them to extend and to retract as they are filled and emptied.
> The system supplies water through canals of small muscular tubes to the tube feet.
> Since the tube feet press against a moving object, water is withdrawn from them, this results in the suction effect.