Question

Visceral mass and a muscular foot is shown by animals belonging to
A. Medusoids
B. Annelida
C. Aschelminthes
D. Mollusca
E. Arthropoda

Answer 1

Hint: The second-largest phylum in invertebrates. Usually, the presence of a hump, covered by a shell can be seen.

Complete Answer:
1) Annelida phylum contains mostly the segmented worm type organisms and therefore the members known as annelids or ringworms also.
2) The Medusoids as the name suggests they have medusa; therefore their prime members are jellyfish-like organisms (umbrella-shaped and gelatinous with tentacles).
3) Aschelminthes are pseudocoelomate, and the organisms are vermiform but not segmented hence can be differentiated from annelids.
4) The mollusks (also can be spelled as mollusks) is the second-largest phylum after Arthropoda in invertebrates. They are usually aquatic, especially marine, a few freshwater and some are terrestrial.
- Mollusks have a ventral surface, for creeping, swimming, and burrowing purposes and thus modified into the muscular foot. The hump present in the dorsal surface of their coelomate body consists of visceral organs like heart, kidney, digestive system, etc.
This hump or visceral mass is covered by a mantle which specifies this phylum from others.
5) Arthropoda is the largest phylum in invertebrates and any hump-like structure is not present in their dorsal surface.

Therefore the correct answer to the given question is (D), i.e. mollusks.

Note: - The shell formation in mollusks is done by the material secreted by the epithelium (ectodermal) cells of the mantle. As the organism ages the shell strength and thickness increase. This shell provides safety to the delicate visceral organ.
- Characteristics features of the Mollusca have three major points: mantle layer, shell and foot, and radula (the rasping organ).