Question

In the T.S. Pheretima , the correct sequence of the body wall layers from the outer to the inner side
A) Circular muscles
B) Parietal peritoneum
C) Epidermis
D) Cuticle
E) Longitudinal muscles
a) C B E A D
b) D C E A B
c) D C A E B
d) D B A E C

Answer 1

Genus Pheretima consists of the earthworms in the majority. It belongs to the phylum Annelida. They usually live in the burrows made by them in the soil. They are very useful for providing the aeration to the soil and it also helps in the composting of the dead organic matter.

Complete answer:
The body wall of the Pheretima is very thin and elastic in nature. The outermost layer is of the cuticle which is a thin, elastic, and non-cellular layer covering the whole body of the worm. This layer provides the function of the protection. It is secreted by the columnar epithelial. Then comes the layer of the epidermis which consists of the tall columnar cells which form the epidermis. It consisted of the supporting cells, gland cells, basal cells, and sensory cells. There are muscles that are present below the epidermis. This muscle layer is composed of the circular muscles and longitudinal muscles. The circular muscle is a thin and continuous layer present around the body and consists of the porphyrin pigment present in it. The contraction of the circular muscle makes the body long and narrow. The longitudinal muscle on the other hand is thicker. The contraction of the longitudinal muscle makes the body short and broad. Then the body is lined by the thin layer of coelomic epithelium. It forms the outer boundary of the coelom so it is called the peritoneum. The order of the body layer from outer to inner is cuticle, epidermis, circular muscles, longitudinal muscles, and the last layer of peritoneum.
So, the answer is ‘c) D C A E B’.

Note: The covering of the body or cuticle provides the coverage to the body and helps in the protection of the soft internal organs from getting damaged. It provides a definite shape to the body. The thin and moist body of the worm helps it in the respiration through the skin.