JELLYFISH
CASSEOPEIDEA
Mangrove Upsidedown Jelly
Cassiopea xamachana
Size
To 30cm

Description
:
Flattened dome with 4 branching oral arms with grape-like clusters.
Numerous brown leaf-like appendages (cf Upsidedown Jelly, C. frondosa). Green-greyish, sometimes blueish, reddish.

Ecology
Although they can swim, usually found resting on the bottom with the oral arms upwards to allow the symbiotic (mutualism) algae to photosynthesize and produce food for the animal. 
It does not have the typical physical characteristics of jellyfish. The green or gray/blue coloration is the result of numerous densely packed symbiotic zooxanthellae, e.g. Symbiodinium microadriaticum. The medusa, the dominant adult phase of the life cycle, possesses four branching tentacles that extend from the body, up into the water column. These structures are used in feeding and provide nutrients in combination with what is made available by the photosynthetic dinoflagellates. The large, dome shaped exumbrella of the medusa contains a central depression that is used mainly for attachment purposes as the up-side down jellyfish remains sedentary throughout a majority of its lifecycle.
Resides inshore in shallow, tropical, marine waters, on particular sandy mudflats. It most commonly uses muddy substrata in mangrove leaves to settle upon.
Mild sting.

Life Cycle
Cassiopea xamachana is dioecious, with each sex contributing one type of gamete (sperm or eggs) that will combine to form a zygote. The developing embryos are covered in specialized mucus and wrapped around the bases of sex specific vesicles. This brooding will continue until cilliated planula emerge and begin to swim, commonly characterized as searching behavior. Eventually, the larva will settle on a suitable substrate and irreversibly attach, beginning the metamorphosis into the sedentary polyp stage of the life cycle. Once the development of the oral opening is complete the scyphopolyp will begin to acquire photosynthetic algal symbionts. After acquiring the needed amount of Symbiodinium and when temperatures exceed 20◦C, these scyphistomae will begin to strobilate through a process called monodisc strobilation. Through this process the calyx, the spicules containing a portion of the upper tentacular part of the polyp, will constrict and eventually separate. Over the course of the following week this will transform into an ephyra, an immature medusa stage of the life cycle. The polyp will regenerate its lost tentacular portion and the ephyra will continue to grow and mature to adulthood as a sexually reproducing medusa.
    Ecological Descriptors
Habitat Size (cm) Diet Behaviour Sex 
S, M, Man 30 Pla * I F
Mangrove Upsidedown Jelly
292
* Much energy is gained from symbiotic algae