Question

Coelom of hemichordates is
A. Schizocoel
B. Enterocoel
C. Enterocoel with differentiation of three region
D. Absent

Answer 1

Hint: Hemichordate is the subphylum of the phylum chordates because they do not have a true notochord. Hemichordates are also termed as coelomate that means they have a true coelom. The coelom is the body cavity present between the body wall and gut.

Complete Answer:
- Coelom of hemichordates, it is an enterocoel with three different regions. Hemichordata is a subphylum of phylum chordates. As the name suggests that this phylum has some characteristics which are common to chordates.
- Hemichordates are the enterocoel with three different regions that are proboscis, collar, and trunk. It is also termed as enterocoelomates. It is present in most animals as the body cavity contains the digestive tract and other organs.
- Note that it is the cavity that is lined mesodermally between the outer body wall and the alimentary canal. Coelom formation starts in the gastrulation stage during the development of an embryo. Schizocoel is not present in the hemichordates; it is formed by the breakdown of mesoderm.
- The coelom formation by the mesoderm splits into two layers, the parietal layer and the visceral layer. The first parietal layer connects to the body wall or ectoderm and the second visceral layer surrounds the endoderm or alimentary canal.
- Apart from the above reasons, coelom plays a very important role in the immune system in the form of coelomocytes. It also has a hydrostatic skeleton. It can also allow the growth of muscles independently. Hemichordates organisms are also called coelomate organisms due to the presence of coelom.
Examples are annelids, mollusks, arthropods, echinoderms, hemichordates, and chordates. On this basis, organisms get divided into three categories
a. Acoelomate (coelom is absent)
b. Pseudocoelomates (false coelom is present)
C. Coelomate (true coelom is present).

According to the above explanation, we can say that the correct answer to this question is option ‘C’ Enterocoel with three different regions.

Note: Hemichordates are also called coelomates. It has enterocoel coelom with separate three parts that are proboscis, collar, and trunk. This is the space between the body wall and the alimentary canal lined by the mesoderm.