Define the term: Coelom.

(N/A) The coelom is defined as the body cavity that is lined by the mesoderm layer on all sides.
In animals,the presence or absence of a cavity between the body wall and the gut wall is very important in classification.
Animals possessing a coelom are called coelomates (e.g.,annelids,molluscs,arthropods,echinoderms,hemichordates,and chordates).