Lifecycle/Reproduction
The lifecycle
of Aurelia aurita is composed of two major stages: polyp and medusa.
The jellyfish embryo develops into ciliated planula larva which implant s 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. |