Semaeostomeae - Jellyfish, Oral Arm

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Semaeostomeae (literally "flag mouth") is an order of large jellyfish characterized by four long, frilly oral arms flanking their quadrate mouths. The umbrella is domed with scalloped margins, and the gastrovascular system consists of four unbranched pouches radiating outwards from the central stomach; there is no ring canal. 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). Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria.