Question

Coelom is formed by the splitting of
(a) Mesoderm
(b) Ectoderm
(c) Endoderm
(d) All of the above

Answer 1

Hint: In the triploblastic species three germ layers are present. The coelom is created by splitting the middle germ layer. This germ layer is responsible for forming a variety of essential structures and organs inside the developing embryo including the skeletal system, the muscle system, the excretory system, the circulatory system, the lymphatic system, and the reproductive system.

Complete step by step answer:
One of the two methods given below can form the coelom or true body cavity which contains the viscera.
- In schizocoelous formation, the coelom emerges from the splitting of mesodermal bands arising from the blastopore area and developing between the ectoderm and endoderm.
- In enterocoelous formation, the coelom comes from archenteron pouches or primitive intestines.
Animals that originate from schizocoely are called schizocoelomate, eg: annelids and arthropods.
A coelom can absorb shock or provide a skeleton with a hydrostatic impact. In the form of coelomocytes, it may also support an immune system that can either be attached to the coelom wall or float around freely in it. The coelom enables muscles to develop independently from the body wall which is the feature visible in the tardigrade digestive tract (water bears) that is suspended within the body in the mesentery derived from a mesoderm-lined coelom.
So, the correct answer is, ‘(a) Mesoderm’.

Note: In most species, the coelom is the principal body cavity and is located within the body to cover the digestive tract and other organs. It is covered with mesothelium in some species. It remains undifferentiated on other species, such as molluscs. Coelom features have been used in the past, and for practical purposes, to classify bilaterian animal phyla into informal groups.