The phylum Cnidaria, includes jellyfish, hydras, corals, sea anemones, and sea fans. Cnidarians are simple soft bodied carnivorous aquatic animals that are radially symmetrical and have specialized tissues. Cnidarians digest through extracellular digestion where food is broken down in a digestive system and then absorbed. Cnidarians have a gastrovascular cavity or a single opening where food is taken in and where wastes are expelled. Cells lining this cavity release enzymes and absorb digested food. Nutrients are then transported to cells throughout the body.
Montastrea Cavernosa (Great Star Coral) Polyps obtain food by preying on small organisms such as plankton and fish. It obtains its food by using its tentacles to catch and paralyze its prey. Once the prey is paralyzed, it is brought into the mouth and gastrovascular cavity where it is to be digested. Once digested, the mouth opens and wastes are released.
Aurelia aurita (Moon Jellyfish) The moon jellyfish, obtains its food by using its tentacles to collect mollusks, plankton, and small jellyfish which are then brought into its body for digestion. The food is brought into its gastrovascular cavity where digestive enzymes break down the food. Wastes are then expelled through its single tentacle lined opening.
Anthothoe chilensis (Striped Anemone) The Striped Anemone, contains a gastrovascular cavity with a single opening that serves as both a mouth and anus from where food is obtained and wastes are excreted. It obtains its food by using tentacles to create moving currents to trap its prey. The prey is then brought into the gastrovascular cavity where it is digested.