Question

Which of the following is detrimental to the pearl industry?
A. Chalina
B. Cliona
C. Euspongia
D. Sycon

Answer 1

Hint: The word detrimental refers or means causing harm. Pearl is a glistening, hard object which is produced within the soft tissues of shelled mollusks and other animals. Natural pearls are extremely rare and are of great economic importance.

Complete answer:
Finger sponge is the common name of Chalina. It belongs to the phylum Porifera and class Demospongiae of that phylum. The structure of the Chalina is like a honeycomb due to the branched structure and overall perforations on the body. Chalina has no specific importance to human beings.
The genus Cliona belongs to the Clionaidae family. They are considered efficient excavators of calcareous materials which include corals and shells. These sponges seek to find shelter in oyster shells and make holes in them. Thus, they are destructive to pearl oysters. They indirectly affect the pearl industry by reducing the number of pearl production in the oceans. Therefore, they are considered detrimental to the pearl industry.
Euspongia is commonly known as bath sponge due to its body texture which consists of wooly, sponge-like fibres. They do not cause any harm to the oyster shells in which pearl production takes place.
The genus Sycon belongs to the family Sycettidae. They are white or cream color sponges. They do not interfere in the process of pearl formation in the oyster shells.
So, option B is the correct option.

Note: Pearls are concentric deposition of calcium carbonate into the shells of pearl oysters. They are used for the purpose of ornaments and jewelry. The value of the pearl is determined by its color, luster, and shine.