Cnidaria
The Cnidaria is a phylum that contains more than 10,000 species of animals that are only found in aquatic environments. In addition to this, these animals also have specialized cells in order to capture their prey. Their bodies are also made up of mesoglea which is something that is a jelly-like substance that is one cell thick. In addition these creatures also have two basic body forms. These organisms can come in the form of jellyfish, coral, and sea anemone.
The Cnidaria do not have a cardiovascular system because they do not need one at all to survive. All of their cells are already in full contact with water, which provides both the nutrients and oxygen that are needed for survival. In addition, the cells of the Cnidaria also experience diffusion in order to export waste and import the oxygen and nutrients. The Cnidaria also has a gastrovascular cavity, this makes the needed nutrients and materials spread to where they need to be in the body of the organism.
The Cnidaria do not have a cardiovascular system because they do not need one at all to survive. All of their cells are already in full contact with water, which provides both the nutrients and oxygen that are needed for survival. In addition, the cells of the Cnidaria also experience diffusion in order to export waste and import the oxygen and nutrients. The Cnidaria also has a gastrovascular cavity, this makes the needed nutrients and materials spread to where they need to be in the body of the organism.