Just because it can be pink and frilly, don’t assume that this animal is female.
Instead, you might want to inquire what the moon jellyfish, which can have hues of pink, purple, orange, or red, had for dinner. It seems that the light shade of color that these gelatinous bodies take on is a result of their meal choice. Carnivorous moon jellyfish that eat certain types of crustaceans show more orange, while those that prefer shrimp tend to have shades of pink or lavender.
Dining choices aside, these late summer visitors never miss a reservation. They are currently drifting in near shore waters and ponds Islandwide. Sometimes you see jellyfish in large groups, called a smack, and sometimes you will find only one or two individuals washed up on the beach or floating alongside of you in your favorite swimming hole.
Look, but don’t touch. While these animals have stinging cells, their sting is not as virulent as some other jellyfish such as the Lion’s Mane. It is also unlikely that moon jellyfish’s stinging cells, called nematocysts, can pierce human skin. They can, however, irritate those who are very sensitive, so give these jelly blobs their space.
Moon jellyfish are identifiable by their four horseshoe-shaped reproductive organs found in the center of their body. This jellyfish can be up to 10 inches in diameter and has more than 200 finger-like tentacles and dangling mucous-laden mouthparts. These waving appendages sting to kill and stick to capture their prey, which is then moved up into their mouth.
The jellyfish is a simple-bodied animal (not related to fish) that consists of only two layers of cells, inner endoderm and outer ectoderm. Within those two layers is the mesoglea or jelly–like substance that makes up their bulk. With this setup, and the fact that they are 95 per cent water, their swimming ability is limited. Moon jellyfish are drifters, floating with the tides, although by contracting their bodies they have some limited movement through the water column.
With that body type, it is not surprising that moon jellyfish do not have a circulatory, respiratory, or excretory system. Simple functions occur on a cellular level. And as an invertebrate, there are no bones about it either.
What is complex about moon jellyfish is their method of reproduction. In their case, breeding can either be very simple asexual budding or a more complex life cycle change that lasts through multiple generations. It makes insect metamorphosis seem simple. The large gelatinous mass that we are most familiar with is the medusa stage. There are male and female medusas and fertilization occurs on the underside of the female. The resultant larvae, called planula, are released into the water and initially float freely. Soon however, the planulas will attach to a hard surface and become sessile polyps that resemble a plant with a stalk. At this stage they can feed and reproduce for years before they go to their next free-floating phase called ephyra. From here, they metamorphose into the well-known medusa.
The name moon jelly refers to this animal‘s circular shape, but interestingly enough in recent history these animals did a fly-by of the moon. In 1991, aboard the space shuttle 25,000 larva of moon jellyfish went into orbit as part of a study of weightlessness.
Whether weightless in space or heavy in Island waters, these jellyfish will persist. They have since prehistoric times, outlasting dinosaurs and even pre-dating sharks. In fact, many jellyfish species are thriving and recently have been called the cockroaches of the open ocean by The New York Times due to their worldwide proliferation. Jellyfish shouldn’t take this intended slander personally, but just continue as they always have and go with the flow.