Figure 1.  Anatomy of the moon jelly, Aurelia aurita.  Redrawn from Barnes 1980. 

Figure 2.  Life cycle of the moon jelly, Aurelia aurita showing typical Scyphozoan life stages.  Embryos develop into a free-swimming larval stage called the planula that settles to the bottom and develops into the scyphistoma.  This stage develops into a strobila that buds off many tiny ephyra that later develop into the familiar jellyfish form of the medusa.  Redrawn from Barnes 1980.