Question

A sponge harmful to the oyster industry is
A. Spongilla
B. Euspongia
C. Hyalonema
D. Cliona

Answer 1

Hint: Sponges are multicellular species, consisting of jelly-like mesohyl sandwiched between two thin layers of cells, having bodies full of pores and channels that allow water to flow through them. Some of the sponges seek to have shelter in the oyster which is harmful to oysters.

Complete answer:
a) The Cliona genus belongs to the family Clionaidae. They are classified as successful calcareous material excavators that include corals and shells. In oyster shells, these sponges tend to find refuge and make holes in them. Thus, for pearl oysters, they are destructive. They are indirectly impacting the pearl industry by reducing the production of pearls in the oceans. They are, therefore, regarded as harmful to the pearl industry.
b) Spongilla is a genus of freshwater sponges in the family Spongillidae found in lakes and sluggish streams. Spongilla sponges bind to rocks and logs and filter water for different small aquatic species, such as protozoa, bacteria and other free-floating pond life.
c) Due to its body texture that consists of woolly, sponge-like fibres, Euspongia is commonly known as a bath sponge. In the oyster shells in which pearl processing takes place, they do not cause any damage.
d) Hyalonema is a marine and free-living sponge found on the coast of New England and America at large depths. They are commonly named as Glass-rope sponge. They do not cause harm to the oysters. Therefore, option D is the correct answer.

Note: Spongology is the branch of zoology which studies sponges. Cliona sponges are detrimental to the oyster industry and indirectly to the pearl industry. Pearls are the concentric accumulation in the shells of pearl oysters of calcium carbonate. They are used for ornaments and jewellery purposes. Its hue, lustre, and shine decide the worth of a pearl.