Question

The collar cord of protochordata consist of a cavity called
A. Protocoel
B. Mesocolon
C. Neurocoel
D. Metacoel

Answer 1

The lower chordates are called protochordate. They have proper notochord. It provides structural support to the body. They do not have a proper skull or cranium. These organisms are triploblastic with the presence of the body cavity.

Complete answer: The protochordate are also known as Acraniata. These are marine organisms that have a notochord. The body is triploblastic, segmented and bilaterally symmetrical which contain coelom. They exhibit organ level or organisation. The body contains three parts: proboscis, collar, and trunk. The collar consists of arms and tentacles. The collar cord arises from the epidermis and is sunken to take a position inside. It is similar to the nerve cord of Chordates. The collar cord consists of a cavity called the neurocoel. The neurocoel is present in the central nervous system which comprises the central canal of the spinal cord and the ventricles of the brain. The neurocoel is mesodermal in origin. It is present in the interior of the vertebra. They have a dorsal nerve cord.
a) Mesocolon is present in humans. It is the organ which attaches the intestine. Metacoel is the cavity of the medulla oblongata.
Thus, the correct answer is option C.

Additional information: Other characteristic features of Protochordata are:
a) Presence of the pharyngeal slit.
b) They do not have a backbone.
c) The circulatory system consists of the dorsal heart.
d) The nervous system is diffuse.

Note: Protochordates are invertebrates of the phylum Chordata. This group consists of phylum Hemichordata and subphylum Urochordata and Cephalochordata. Examples of protochordate are Amphioxus , Salpa , Doliolum.