food produced by tiny plants called zooxanthellae; zooplankton
diameter to 13 inches (33 cm)
crown jelly; Family: Cepheidae
Mediterranean Sea, coastal lagoons
At the Aquarium
After receiving Mediterranean jelly polyps from the New England Aquarium, Wyatt Patry, senior aquarist, helped raise them behind the scenes to display them at the Aquarium. "The most unique thing about these guys is probably how fast they grow—from just a few millimeters to the size of a quarter in a couple weeks," he says.
"They start off as polyps and we raise the temperature from 20 degrees Celsius to 25 degrees," Wyatt says. Warming the water causes the Mediterranean jellies to strobilate, or asexually reproduce, and release tiny medusae, or baby jellies. "From there, we put them in floating bowls and that's where they start to grow," Wyatt explains. The Mediterranean jellies then move from the floating bowls into floating bags because they need soft walls to bump up against. "These guys are a little bit more sensitive," Wyatt says.
Mediterranean jellies can live in any of our Aquarium tanks when they grow to be a bit larger. "Once we get them to about the size of a quarter, there's really no special requirement," Wyatt says.
The unusual looking Mediterranean jelly, also known as the "fried egg" jelly, has a smooth, elevated bell surrounded by a ring. It has numerous short, clublike appendages that expand and flatten at the ends, in addition to some longer ones. The clustered appendages contain mouth-arm openings that are colored deep purple.
This jelly only lives for about half a year, from summer to winter. Researchers think this short life span is the result of adapting to a highly seasonal environment where the water temperature varies greatly.
Massive blooms of the Mediterranean jelly appeared in the Mar Menor coastal lagoon in the Mediterranean area after human activities, including agriculture, caused nutrients to seep into ground and eventually to the lagoon through coastal runoff.
Jelly populations naturally ebb and flow. Scientists are now wondering whether human impacts like overfishing, pollution and possibly climate changes might affect jelly populations also.