In ________, a two-layered body wall encloses a single cavity in which digestion takes place.
Cnidaria
In Cnidarians, a two-layered body wall encloses a single cavity in which digestion takes place. Cnidarians possess only one digestive opening, which serves as both the mouth and the anus. This opening is surrounded by tentacles and leads to an internal digestive cavity called the gastrovascular cavity.