Mesoglea is the translucent, inert, jelly-like substance that makes up most of the bodies of jellyfish, comb jellies and certain primitive sea creatures in the phyla Cnidaria and Ctenophora. It acts as the creatures' structural support in water, as they lack bones or cartilage, endo- or exoskeletons, or similar means of support. Because the mesoglea is a gel with a very high water content, these creatures tend to collapse on land.
The mesoglea is an evolutionary advancement in body plan from Porifera (sponges). The lack of very many cells in this structure allows a lower metabolism. This means that cnidarians need to feed less often.
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