Lake With Jellyfish

Jellyfish (also known as jellies or sea jellies or medusozoa) 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 not).  The jellyfish in these groups are also called, respectively, scyphomedusae, stauromedusae, cubomedusae, and hydromedusae. All jellyfish are embodied in the Medusozoa  subphylum. Medusa is another word for jellyfish, and as such is used to refer specifically to the adult stage of the life cycle.