What is the function of endoderm and endoderm in coelenterates?

The outer, ectodermal layer is involved in a number of functions. Due to the skin-muscle cells, which contract and relax, the hydra can move and respond to external stimuli by contracting these cells, reducing its body size. The signal about the effect of the stimulus on the hydra is transmitted by other cells of the outer layer – nerve cells. They are distributed throughout the ectoderm and are interconnected in the form of a network. The function of protection and hunting is performed by stinging cells.
The inner layer performs the function of digestion, involving in this process glandular cells, which secrete substances that dissolve food and digestive-muscle cells involved in the movement of food through the intestinal cavity and the absorption of digested substances from it.