, also known as ectoplasma
, is the clear, inert, jellylike substance that makes up most of the bodies of jellyfish
, comb jellies
and certain primitive sea creatures in the phylum cnidaria
. It acts as the creatures' structural support in water, as they lack bones
or other more common means of support. Because mesoglea is a gel with such a high water content, these creatures tend to collapse on land.