Cnidaria Essay -- essays research papers

phylum Coelenterata is a large phylum composed of some of the most beautiful of both the salt and freshwater organisms the true jellyfish, box jellyfish, coral and sea anemones, and hydra. Although phylum Coelenterata is an incredibly diverse group of animals, there are several traits that marry them together. Most cnidarians are dipoblastic, which means that they are composed of only twain layers of cells. The outer layer is known as the ectoderm or epidermis, and the inner(a) layer is known as the endoderm or gastrodermis. These layers contain the gist nets that control the muscular and sensory functions of the animal. Between these layers is a jelly-like noncellular center of attention known as mesoglea, which in true jellyfish constitute the huge bulk of the animal (hence their common name). In other species, the mesoglea may be nearly absent. All cnidarians have a single opening into the carcass which acts as both the babble and anus, taking in food and sack waste. I n most species the mouth is lined with tentacles which act to capture food. The mouth leads to a body cavity known as the coelenteron, where the food is digested. This body cavity has given this phylum its other, less commonly used, name of Coelenterata. Cnidarians have a complex life cycle that, depending on the species, may alternate in the midst of two forms. The first form is known as a polyp, which is stalkless (anchored to one spot). The polyps are tubular in shape, with the mouth, often lined with tentacles, confront upwards. The bodies often con...