What is Cnidaria? What is it made up of? Who are the members that belong to his group? Cnidaria is an exclusively aquatic phylum. It is a group that is represented by the members, who are also called 'polyps', and these are sea anemones and corals, and also by 'medusae', which are creatures like the jellyfish. In general, both a polypoid as well as a medusoid cnidarian will be either radially or biradially symmetrical and it is an uncephalized animal with one single body opening, which is the mouth. Stinging capsules, which are embedded in the tentacles that are placed around the mouth, generally surrounds the mouth. These stinging capsules are also known as 'nematocysts', and these are capable of acting both as agents of defense as well as of offense. The most important distinguishing feature of a phylum is the presence of the intrinsic nematocysts, and in turn, nematocysts are the most widespread of the three different types of cnidae. (Cnidarians).

             Cnidarians are diploblastic, or, in other words, they are made up of two cell layers, in the body, and in the tentacles, and they are the endoderm and the ectoderm. The endoderm is also known as the 'gastrodermis', while the ectoderm is also known as the 'epidermis'. The 'mesoglae' is found between these two cell layers, and this can be as minimal as a bit of binding element like glue, like in the case of a hydra, to hold the two layers together, or it can be as big as the body of the animal, like in the case of the jellyfish, whose body is made up of a single sac-like space, also known as the 'coelenteron'. This space communicates with its surrounding areas by way of its mouth, while the coelenteron serves the function of gas exchange and digestion. All cnidarians are carnivorous, and the tentacles being used for the purpose of capturing their prey. (Cnidarians) .

             Some of the better-known names of cnidarians are the Star Coral, or the 'Astrangia Danae', which is a variety of coral found in New Jersey.