Question

Tube-feet are the locomotor organs of
A) Platyhelminthes
B) Echinodermata
C) Mollusca
D) Arthropoda

Answer 1

Hint:Different animals have different kinds of locomotion systems. Tube feet are very similar in function to suction cups that hold hooks to the wall, and need a wet surface to stick well as well a system of releasing pressure.

Complete answer:
Tube-feet are the locomotor organs of Echinodermata. This phylum includes animals like the starfish. Tube feet work through hydraulic pressure, much like suction cups. The water is pulled in to the arms of the starfish through a water vascular system, and through a series of tubes, moves down into the tube feet. By alternating the water pressure, these feet stick and release to the substratum, propelling the animal along, or moving food towards its mouth.
Answer (A) is incorrect, because Platyhelminthes do not have tube-feet. They may move through a muscular system or beating of cilia on epithelial cells.
Answer (C) is also incorrect. Mollusca like gastropods have a single muscular foot which varies in size depending on the kind of mollusc.
(D) is also incorrect. Arthropoda, which include all the insects, have segmented organs of locomotion. Muscles are attached on the inside of the exoskeleton. Their movement is therefore very similar to that of vertebrates, except that the vertebrates have an endoskeleton.

Hence the correct answer is option ‘B’.

Note:Hundreds of tube-feet or ambulacral are arranged along the arms of the starfish. However, this movement is not coordinated, with each moving independently of one another, so it can be quite jerky.