The coelom is a cavity formed during the embryonic development of some types of animals (annelids, echinoderms, mammals...) called, for this reason, &quotcoelomates".
This cavity is bordered by a mesodermal membrane which forms several organs: dermis, blood circulation system, etc.
The coelom, which full of liquid, has several advantages:
- It creates a space for the growth and movement of organs such as the digestive tube or heart;
- It is a buffer against mechanical shock and thermal variations;
- It forms a hydrostatic skeleton;
- It facilitates excretion of metabolic waste through the liquid that bathes the organs.
In man, coelomic cavities and their walls form the pleural cavities of the lungs, the pericardial cavity that houses the heart and the peritoneal cavity that surrounds the internal organs.