Question

Notochord of Hemichordata is also termed as
A. Buccal diverticulum
B. Midgut diverticulum
C. Intestinal diverticulum
D. None of the above

Answer 1

The classification of animals is based on primitive characteristics, habitats, mode of nutrition, etc. The chordates and hemichordates are also two phylums of animal kingdom in which the hemichordates are primitive forms of notochord.

Complete Answer:
- The hemichordata is a phylum that comprises marine deuterostome animals. They are also considered as the sister group of echinoderms. They are bilaterally symmetrical and triploblastic in nature and can be solitary or may be found in colonies, they consist of a true body cavity that is coelom.
- The hemichordates are considered as half chordates as they have the same characteristics as that of the chordates except, the hemichordates are a more primitive form of notochord that means stomochord means it consists of a nerve system.
- The organisms of hemichordates are reproduced asexually by the process of budding. In budding, the adult organisms produce a bump that grows in full size and then breaks down from the parent body and is considered as the new individual.
- So, buccal diverticulum is a thick walled projection that is extended towards the proboscis stalk inside the proboscis coelom. In short it is a tube like projection. It is tubular outgrowth from the cavity of mouth to the proboscis. The wall is made of a single layer of vacuolated and tall endodermal cells.
- Hemichordata is also termed as half chordata as it comprises buccal diverticulum. The structure looks like a rudimentary notochord found in the dorsal side and it involves providing support for primitive vertebrates.

Thus, the correct option is ‘A’. Buccal diverticulum.

Note: The digestive system of hemichordates comprises the gut that ends in anus terminal. The buccal cavity found behind the mouth leads inside the pharynx that possesses gill slits. This gill slit is involved in the exchange of gases.