|The body plan of a Moon
Jellyfish is in two different forms during its lifetime but both body
plans are fairly simplistic. The primary similarity between both
is that they have radial symmetry. Also, the basic body plan is a
sac-like structure with an internal gastrovascular cavity. The
gastrovascular cavity has one opening which acts as both a mouth and an
anus. The opening is surrounded by tentacles which assist
in feeding and protection.
The body wall consists of three
layers: the epidermis,
the mesoglea, and the gastrodermis. The epidermis is the outermost
layer, the gastrodermis is the innermost layer, and the mesoglea is
between the two.
Moon Jellyfish do not have
lungs, gills, or a tracheal system of any sort. They simply
receive oxygen by diffusion through their thin membrane. Their
large surface area to volume ratio increases their ability for diffusion.
are found most abundant on the
tentacles or oral arms. In the cnidobcytes are nematocytes which
sting as a form of protection.
The first major stage is the polyp
stage. Two distinctive characteristics of this organism are that
it is usually attached to a substrate and
has a mouth that opens upward.
The second major stage is the
medusa stage which is characterized by a bell-shaped body, being free-swimming, and having a
mouth that opens downward. An
identifiable characteristic of Moon Jellyfish is 4 violet or pink,
crescent shaped gonads at the center of the bell-shaped body.