Cassiopea is only found in shallow waters with high light levels on the sea floor, usually lagoons, mud flats and mangrove swamps. They do this because like corals they harbour algae in their tissues, which provide food to their host by photosynthesis. As well as their algae, they can also feed on smaller organisms as they retain the nematocysts, the stinging cells which predatory jellyfish use to kill prey, although to humans at least the sting is very weak. The group of jellyfish they belong too has modified their internal anatomy – the primary mouth at the center of the bell is closed and instead secondary openings into the digestive cavity open at the edge of the body.
|A different morph - colour is due to symbiotic algae|
|Lateral view showing the feeding arms|
(images from wikipedia)