Moon Jelly (Aurelia aurita)
Color: Translucent white with darker tentacles
and four yellowish pink gonads.
Size: Up to 12 inches in diameter.
Habitat: Open water, near the surface, close to shore.
Seasonal appearance: Late summer to mid-fall.
The moon jelly is one of the most common jellyfish in Rhode Island. Its body shape resembles an umbrella, with four equal-sized horseshoe-shaped gonads in the center of its body. Moon jellies are made up almost entirely of water and will not hold their shape when out of the water. Rather than having long tentacles like other species of jellyfish, the moon jelly has many relatively short tentacles. Four elongated feeding appendages, called "oral arms," surround the mouth.
Life History and Behavior
This species of jellyfish doesn't feed with long tentacles; rather, it uses the underside of the umbrella, or bell, which is covered with a mucous lining, to trap plankton. The oral arms are used to scrape the plankton off the mucous lining and carry it into the mouth. This method of feeding is known as "suspension feeding." In general, jellyfish are considered to be among the largest members of Rhode Island's planktonic community. They are categorized as plankton because they don't have any method of locomotion beyond raising and lowering themselves in the water column. As such, they are at the mercy of tides and currents.
Adapted from The Uncommon Guide to Common Life on Narragansett Bay. Save The Bay, 1998.