The medusa, or the bell of the moon jellyfish can range between 5 to 40 cm in size. Their medusa, or bell, is translucent and often has a pattern of stripes or spots. The four horseshoe shaped gonads of the moon jellyfish are easily visible through its translucent bell and offer the simplest way to identify a moon jellyfish. The moon jellyfish, unlike some other species of jellyfish, has both oral arms and tentacles to facilitate its feeding process.
The moon jellyfish are commonly found in coastal regions in warm and temperate waters. They are found in almost all the waters of the world between 70 degrees N and 40 degrees S, but are most abundant in Atlantic, Pacific and Indian Oceans. They are also known to inhabit inland seas and sometimes, even brackish waters. In brackish waters, however, the bell of the moon jellyfish is a lot flatter due to decreased salinity. Although moon jellyfish can withstand salinity as low as 0.6%, they thrive best in waters with relatively high salinity. Moon jellyfish can also withstand temperatures between -6 degrees C and 31 degrees C, their optimum temperature range is between 9 degrees C and 19 degrees C.
Like most other jellyfish are only capable of an upward thrust on their own and essentially depend upon the tides and currents of the waters to keep them suspended and for horizontal movement. Moon jellyfish usually stay near the surface of the water and travel with the tides.
The Moon jellyfish is carnivorous and mainly feeds on plankton like mollusks, crustaceans and copepods. They are also known to feed on zooplankton like hydromedusae and ctenophores. Moon jellyfish of all ages are equipped with venom filled nematocysts on their tentacles to help them procure food by stinging their victim and trapping in within mucus. On the other hand, moon jellyfish are fed upon by a number of large fish and the sea turtle. Even some marine birds are known to feed on moon jellyfish, especially because moon jellyfish tend to stay close to the surface of the water.
Moon jellyfish reproduce sexually and have both males and females in the species. They are most likely to be sexually mature around spring and summer of each year.
Moon Jellyfish are the most commonly kept species of jellyfish, in both public aquariums and by serious hobbyists. If you have visited an aquarium that keeps jellyfish, you are very likely to have seen specimens of these species. Learn more about keeping jellyfish as pets.
The sting of the moon jellyfish is not fatal or dangerous to humans. In severe cases, the victim may experience some stinging sensation on the surface of the skin where he/she has been stung.
Written by Nathan Dickerson and Sudarsana Sinha.