Body Plan
Fact Sheet


The lifecycle of Aurelia aurita is composed of two major stages: polyp and medusa.  The jellyfish embryo develops into ciliated planula larva which implants into the ocean floor and grows into a scyphistoma.  The scyphistoma becomes a strobila which is the mature polyp form.  The polyp form is usually still rooted in the ocean floor and thus unable to swim.  The strobila undergoes one of a variety of types of asexual, or occasionally sexual, reproduction resulting in production of either more polyps or formation of ephyra which are simply small medusa.  The first form of asexual reproduction that may occur is budding in which a new organism grows out from the body of the parent organism.  This is the most common way for an ephya to form.  Fission, which is when an adult splits lengthwise into two new organisms, also may occur.  Lastly, fragmentation, which is when part of an adult regenerates missing pieces to form a complete organism, can take place.  The ephyra matures into the medusa which is the jellyfish form we are all familiar with.  The medusa will sexually reproduce to create embryos.  Typically this process involves gametes being released from the mouth/anal opening and fertilization occuring in open water.  The eggs then hatch into ciliated larvae.  The larvae become part of the plankton, settle, and grow into a polyp.

In some Aurelia aurita, the polyp stage does not exist.