Coelom 75003 216967765 2008-06-04T00:52:50Z 122.109.58.162 {{unreferenced|date=April 2008}} The '''coelom''' (pronounced "seal-um") is a fluid filled cavity formed within the [[mesoderm]]. Coeloms developed in [[triploblast]]s but were subsquently lost in several lineages. Loss of coelom is correlated with reduction in body size. Coeloms are absent in [[diploblastic]] animals such as [[cnidarian]]s. Functionally, a coelom can absorb shock or provide a [[hydrostatic skeleton]]. It also allows organs to grow independently of the body wall. This can be seen in the digestive tract of earthworms and other [[annelid]]s, which is suspended within the body in a [[mesentery]] derived from a mesoderm-lined coelom. In [[mammals]], the coelom forms the [[peritoneal]], [[pleural]], and [[pericardial sinus|pericardial]] cavities. In the past, zoologists grouped animals based on characters related to the coelom. The presence or absence of a coelom and the way in which it was formed was believed to be important in understanding the [[phylogenetic]] relationships of animal [[phyla]]. However, recent molecular phylogenies have suggested this characteristics is not as informative as previously believed. ==See also== *[[Abdominal cavity]] {{developmental-biology-stub}} [[Category:Animal anatomy]] [[Category:Developmental biology]] [[ca:Celoma]] [[fr:Cœlome]] [[it:Celoma]] [[ja:体腔]] [[pt:Celoma]] [[ru:Целом]] [[sr:Целом]]