Question

Notochord like structure is present in hemichordata in the region
A. Proboscis
B. Collar
C. Trunk
D. Tail

Answer 1

Hint:-Hemichordata is a separate subphylum of Chordata. This is because they do not show any similarities with chordata except the presence of Notochord like structure. Their body is divided into three parts such as proboscis (protostome), collar (mesosome) and trunk (metasome).

Complete step-by-step solution:-
Hemichordata belongs to phylum Chordata also called Acorn worms. They are separated from other classes of phylum Chordata because of their similar characteristics. The name hemichordata means half Chordata. They possess only typical Chordates characteristics. Hemichordata are differentiated by a tripartite partition of the body. At the forward end of the body there is a preoral lobe, behind the preoral lobe there is a collar and then the last portion is trunk. They have branchial openings or gill slits that open up into pharynx. This pharyngeal gill-slits is the only link that connects hemichordata with the phylum Chordata. There is no central nervous system. The nervous tissues are concentrated in the collar region which is linked with the nervous system in the epidermis. They have bilateral symmetry and are found either in solitary or colonial conditions. Heart and kidney present in preoral lobe also known as proboscis and are supported by stomochord a notochord like structure. Notochord in hemichordata is present in proboscis.
Hence the correct answer is option A.

Note:- Hemichordata do not show any similarities with phylum Chordata except the presence of notochord like structure which is a false Notochord. So hemichordata is considered as a separate sub-phylum. Notochord in hemichordates is also known as buccal diverticulum. Hemichordata consist of three classes i.e. Enteropneutsa, Pterobranchia and planctosphaeroidea.