What is a secondary body cavity and how does it differ from the primary? what are its functions?

The primary cavity does not have its own cell walls, it is formed from the remnants of the blastula. The secondary cavity has a coelomic epithelium, formed from the mesoderm and fills the space between the body and internal organs with fluid. The secondary cavity appeared already in annelids. The value of the secondary cavity is the division of the body into different sections; performance of the support function; carries out the movement of nutrients to tissues and the release of metabolic products, the formation of germ cells and phagocytes.