Moon Jelly    Aurelia labiata

 

The Moon jelly is a large, semi-transparent relative of the Lion’s Mane jelly and the Fried Egg jelly.  The body color ranges from light white of the swimming bell and mouth to a whitish pink of the horseshoe shaped gonads.  The Moon jelly can be seen in the late summer and fall usually in large groups that may include several hundred or more individuals.  Why they form aggregations is not known, although several theories have been suggested such as orientation to currents or the earth’s magnetic field or for mass spawning. They normally range in size from 5 to 10 inches (swimming bell diameter).  Occasionally they have been found up to 15 inches.


The edge of the swimming bell is scalloped into eight major lobes each of which are notched resulting in 16 individual lobes.   A close relative, the Atlantic moon jelly (A. aurita), may occur here, but it has only eight, undivided lobes.


Extending along the margin of the swimming bell are fine tentacles.  Within the bell, the corners of the mouth sprout frilly lobes (oral arms) that are used for feeding.


The females carry developing larvae on the oral arms.  After “hatching”,  the larvae swim off and attach under floats or other underwater hard surfaces away from sunlight.  After feeding over the winter, the anemone-like form , called a scyphistoma,  buds off juvenile medusa that swim away as the next generation.


The native Moon Jelly ranges from SE Alaska to southern California and west the Hawaii.