The Phylum Cnidaria
The cnidaria phylum is consisted of many beautiful salt water and fresh water organisms. Some of these animals are: Hydra, Sea Anemones, Jellyfish, then box jellyfish, and Corals. These animals are specifically found in aquatic or marine environment. Cnidaria aslo have specialized cells used for capturing prey called cindocytes.
Jellyfish's Circulatory System
One animal that lies in the Cnidaria class is the jellyfish. Jellyfish are different from other animals. Jellyfish are such a unique kind of marine animal that they actually dont have a specialized circulatory system. They dont even have a specialized respiratory system or nervous system. They can easily absorb oxygen when needed through their thin bodies. They can also absorb food through their gastrodermis. The gastrodermis then absorbs the nutrients into the epidermis.
Circulatory System in Coral
Another organism in the Cnidaria phylum is the coral. Corals, Coelentrerates, have a gastrovascular system. A gastrovascular system is a type of system where the circulatory system and the digestive system are meshed together. The gastrovascular system in the Coral actually gives better circulation through the many species of fish that live symbiotically with it. Living symbiotically means that two organisms that have a close association with each other and may or may not benefit each other.
Remember this from a certain movie involving a clown fish?
This organism is a Sea Anemone. Sea anemones their bodies are composed of an adhesive peal disc, or a foot, a cylindrical body, and an array of tentacles surrounding a central mouth. Like the circulatory system in Corals, Sea Anemone also have a gastrovascular system. Since sea anemones dont have a centralized circulatory system, they have to circulate their oxygen and nutrients somehow. Anemones breath air through the openings in their mouths. They are sort of like humans in the way that they are carnivores. They trap and eat their prey using their venomous tentacles. Certain fish also live symbiotically with the Sea anemone such as clown fish. The clown fish is provided with shelter from predators due to its immuness to the anemones toxins; at the same time, the clownfish allows more circulation in and out of the Sea anemone.