Question

Discuss the evolution of the coelom and pseudocoelom. What advantages do coelomate animals have over acoelomates?

Answer 1

The pseudocoelom is the first partial body cavity to evolve. It is filled up with the fluid. It lies between the body wall and the digestive cavity. The pseudocoelom is said to arose from the blastocoel during embryonic development in the roundworms ancestors. It is then progressed to the true coelom during evolution. A theory says that the coelomate is evolved from the gastric pouches of some cnidarians. These gastric pouches are said to be separated from gastric cavity and form coelom pouch.

The main advantages the coelomates have over acoelomates are as follows-

1. The coelom helps in the circulation of the nutrients and gases in the body. The acoelomates generally have pores to exchange gases and water which is less efficient.

2. The coelom also helps the proper removal of waste products in an efficient manner unlike acoeloms.

3. The coelom is filled with body fluid which helps in the locomotion of organisms.

4. The internal organs are well protected in the coelomates.