Mesoglea

Mesoglea is a special kind of material found in some sea creatures like coral and jellyfish. It is part of the extracellular matrix, which means it is made outside of cells. This material acts like a support structure for these animals, helping them keep their shape.

Mesoglea is found in animals called cnidarians, which include jellyfish and coral, as well as in ctenophores, which are often called comb jellies. It works like a hydrostatic skeleton, meaning it helps these creatures stay firm and stable in the water.

This material is different from something called mesohyl, which is found in sponges. While both are made of material outside cells, they serve different purposes in their respective animals.

Description

The mesoglea is mostly made of water. It also contains special proteins like collagen and heparan sulfate proteoglycans. In animals like Cnidaria and Ctenophora, the mesoglea has tiny muscle and nerve bundles. It also has wandering cells called amoebocytes that help clean up debris and fight off harmful germs by making protective chemicals.

The mesoglea acts like an internal skeleton, giving support to the body. It can stretch and then return to its shape thanks to its stretchy properties. However, without the support of water, it isn’t strong enough to hold up the body on its own, so these animals usually flatten or collapse when out of water. The mesoglea sits between two layers: the outer epidermis and the inner gastrodermis. In some bigger jellyfish, the outer layer may wear away, leaving the mesoglea directly exposed to the water.

Uses of the term

Some scientists use the word mesoglea to talk about layers in animals like jellyfish and sponges. They do this to avoid mixing it up with a similar word used for studying how animals develop.

Other scientists, like Brusca & Brusca in 2003, suggest using mesoglea only for certain animals and keeping the original word for development studies.