Class Scyphozoa
Organisms of this class are referred to as "true jellyfish". These organisms are all marine, and dominantly medusae. Their medusa lack a velum. the mesoglea of these organisms have amoeboid mesenchyme cells, and have cnidocytes in the gastrodermis and epidermis. Gametes are produces gastrodermall. Scyphozoans have cilia in their gastrodermal cells to help circulate seawater and aid in digesting food. Scyphozoans can be dangerous to humans, but usually arent. Some organisms are able to sting humans, such as the Mastigias quinquecirrha. Scyphozoans are dioecious. During reproduction, the planula develops into a polyp called a scyphistoma (also known as a strobila). The scyphistoma lives for a year, during this year it goes through budding and creates small medusae, called ephyrae. Repeated budding causes ephyrae to stack on the scyphistoma, later on the ephyrae are released and eventually mature. This process is occurs in Aurelia.
Another type of scyphozoa is the Aurelia, its margins are divided by notches. This organism has an extensively branched canal system. Aurelia feed by slowly sinking and trapping organism on their epidermal surface with mucus. Cilia helps transfer the food to the margins of the medusa. Aurelia have four oral lobes that hang from the manubrium that scrape food from the margins of the medusa. Then cilia on the oral lobes carry food to the mouth. Aurelia have eight specialized structures in its margins, called rhopalia. Rhopalium have sensory structures surrounded by rhopalial lappets. Two of the dents are for sensory lappets (assumed to be olfactory). Associated with the rhopalia is a statocyst and photoreceptor called ocelli.