Question

Define coelom. Explain the two types of coelom formation in animals.

Answer 1

Coelom:

1. Coelom means body cavity.
2. The true coelom is seen as a body cavity that is formed during embryo development from the 3 germinal layers.
3. The body cavity is a fluid-filled space that has organs in it.
4. The coelom was lined by the mesodermal epithelium cells.

Types of coelom: Based on formation they are of two types:

1. Schizocoelom
   1. It is seen in the protostomes.
   2. The body cavity or coelom originates due to the splitting of the mesoderm.
   3. One part of it attaches to the ectoderm and the other surrounds the endoderm.
   4. The space present between them further develops into the coelom.
   5. The blastopore forms the mouth.
   6. Examples – Arthropoda and Annelida.
2. Enterocoelom
   1. It is seen in the deuterostomes.
   2. The coelom is formed due to the fusion of the internal outgrowths of the archenteron, which pinches off and fuses together to form a coelom lined by the mesoderm.
   3. Examples – Chordates and Echinodermata.