Question

Porous plate present on the aboral side of starfish is
A. Umbilicus
B. Genital pore
C. Madreporite
D. Mouth

Answer 1

Hint: A starfish is an echinoderm that has a special vascular water system. The system consists of a porous opening on the upper surface of the aboral side of the body. It is a light-coloured calcareous opening. Also, it makes an essential component of the water vascular system. These are sieve-like plates in certain echinoderms.

Complete answer: Any Echinoderm contains a calcareous light-colored pore that opens externally on the aboral side of the body. Starfish is also an echinoderm and consists of this pore plate. It is used to filter water and hence aids in the water vascular system. It also acts as a pressure-equalizing valve as starfish lives in the crushing pressure of the deep sea. The pore plate appears like a small red or yellow button like spot. The central disk of the starfish consists of this pore plate and is called Madreporite. The Madreporite resembles a stony coral structure called Scleractinia. The water vascular system is not only involved in the filtration of water but it also aids in locomotion and feeding. The water vascular system is composed of a series of water-filled ducts. These ducts help in feeding and locomotion. The water vascular system contains other structures called the stone canal, the radial canal, the lateral canals, and the tube feet. Radial canals extend into the five arms attached to the central body of the starfish.
Hence, the right answer is option C.

Note: The starfish are mostly found crawling over the sea surface. They are found at 100 feet depths where the crushing pressure of the water makes them adapt by some modifications. The madreporite is one of these structures that help to stabilize the pressure gradients. Also, the water vascular system is very essential for starfish survival.