Jelly Fish

Jellyfish (also known as jellies or sea jellies) are free-swimming members of the phylum Cnidaria. Jellyfish have several different morphologies that represent several different cnidarian classes including the Scyphozoa (over 200 species), Staurozoa (about 50 species), Cubozoa (about 20 species), and Hydrozoa (about 1000-1500 species that make jellyfish and many more that do notThe jellyfish in these groups are also called, respectively, scyphomedusae, stauromedusae, cubomedusae, and hydromedusae; medusa is another word for jellyfish.
Jellyfish are found in every ocean, from the surface to the deep sea. Some hydrozoan jellyfish, or hydromedusae, are also found in fresh water and are less than half an inch in size. They are partially white and clear and do not sting. This article focuses on scyphomedusae. These are the large, often colorful, jellyfish that are common in coastal zones worldwide