What are cnidarians?
Cnidarians are also called coelenterates and are comprised merely of internal and external dermal layers. They have large gastric cavities (the gastrovascular cavity) and the body is radially symmetrical. They have cnidocytes that are used for attack or defense. Alternation of generations is commonly observed in their life history. Jellyfish, sea anemones, corals, and sea feathers are well known cnidarians.