Answer:
diploblastic
Step-by-step explanation:
The Cnidaria phylum includes aquatic animals of which freshwater hydra, jellyfish or jellyfish, which are normally oceanic, and corals and sea anemones.
The body of the cnidarians is basically a sac formed by two layers of cells - the epidermis on the outside, and the gastrodermis in the interior - with a gelatinous mass between them, called mesogleia and open to the outside. For this reason, the cnidarians are said to be diploblastic.