The adult stage of the jellies' life cycle is called the medusa . This is the stage that many of us think of when we think jellyfish. Adult jellies are either male of female.
Males project their sperm out into the water.
Female jellies either do the same with their eggs or, like the moon jelly, hold them under their bell. Gametes Joyce Bergen Eggs are fertilized by chance, either out in the water or under the protection of the female jelly's bell. After the moon jelly's eggs hatch the larvae hang out under the mother's bell for a time. Larvae Joyce Bergen Out of the eggs hatch the jelly larvae, beginning yet another stage of their planktonic lives. From here the larvae float around the ocean searching for a solid surface to attach to.