It goes by many names (moon jelly, moon jellyfish, common jellyfish and saucer jelly) but scientists call it Aurelia aurita. In Alabama it’s commonly called the moon jelly, pest or other names not fit to print. The moon jelly, when mature is about the size of a dinner plate.
Before Hurricane Lee this year there were ten of thousands of these jellyfish in Alabama and Mississippi coastal waters. They were particularly heavy off the barrier islands and drifted around Fairhope and its pier, washed up heaps on the barrier Islands and were so numerous in Orange Beach waters that it looked as if you could walk across Perdido pass without getting your feet wet. Why they are here in such numbers is a question that needs to be asked? It doesn’t seem to have anything to do with the oil leak.
The moon jelly is found throughout nearly all of the world’s oceans and ranges from the tropics to the north 70 degrees near Iceland and Norway. In it goes south down to Australia and the Indian ocean. In our part of the world this species is found along the eastern Atlantic coast of Europe and western Atlantic coast of North America in New England, Eastern Canada and the Gulf Coast. The moon jelly is an inshore genus and can be found in nearshore waters, bays, bayous and creeks.
The adult jellies can reach up to 16 inches in diameter. The juveniles bud off of polyps that mature on the ocean bottom. They feed on plankton from various species including clams, crabs, fish eggs and most of the various types planktonic organisms. Both the adults and the larvae of moon jelly have nematocysts they use to capture prey and to protect themselves from predators. The nematocysts use mucus to capture food which is moved by down into the stomach
Moon jellyfish don’t sting so if you feel their soft bodies against your arms and legs as you swim don’t worry about it. They ranging in color from a light pink to white and have short tentacles with and obvious four-leaf clover design in their center.
They are eaten by a large number of predators which includes the Ocean Sunfish, sea turtles and other very large jellyfish. Moon jellies are also eaten marine birds which can do some serious amount of damage to the jellyfish which are often found at the surface.
Moon jellies die after several months of living and reproducing. It’s rare for moon jellies to live more than about six months. After years of study marine scientists have determined that moon jellies’ numbers have a ten year cycle in the Gulf of Mexico. Apparently, we’re at the beginning of a cycle. So, if this trend holds we should be blessed with their company for the next several years.
Maybe somebody could think up a jellyfish excluder device for shrimp trawls as it is just about impossible to catch anything in areas with moon jellies around.
Think Global – Act Local!