Coelom

Coelom
Cross-section of an oligochaete worm. The worm's body cavity surrounds the central typhlosole.
Details
Pronunciation	(/ˈsiːləm/ SEE-ləm, plural coeloms or coelomata /siːˈloʊmətə/ see-LOH-mə-tə)
Identifiers
Greek	koilōma
Anatomical terminology [edit on Wikidata]

The coelom (or celom)^[1] is the main body cavity in many animals^[2] and is positioned inside the body to surround and contain the digestive tract and other organs. In some animals, it is lined with mesothelium. In other animals, such as molluscs, it remains undifferentiated. In the past, and for practical purposes, coelom characteristics have been used to classify bilaterian animal phyla into informal groups.