What are the names of the two types of true tissue found in the Cnidarians?

Cnidarians, or jellyfish, are made of two cell layers called the ectoderm and the gastrodermis. There is also another jelly-like substance that fits in between the two layers called the mesoglea; however, it is non-cellular and therefore, not a living tissue structure.

The outer ectoderm on a jellyfish contains the cnidocysts, or the stinging cells. The inner layer, the gastrodermis, is the lining of the gut of the jellyfish. Jellyfish are diploblastic, which means that there are only two cells and tissue layers in the organism. The mesoglea is the layer in between the ectoderm and the gastrodermis, which contains collagen fibers and scattered cells; this layer is also known as the mesenchyme.