zooplankton; brine shrimp
diameter to 24 in. (60 cm)
Mediterranean jelly; Family: Cepheidae
At the Aquarium
The crown jelly is unlike any jelly species here at the Aquarium—its bell is covered with spikes. Our exhibit is the result of a two-year husbandry effort by Senior Aquarist Wyatt Patry, and our institution is the first to successfully raise the jellies from polyps to adulthood.
"We received the polyps from Zoo Berlin, which got them from waters off Japan," Wyatt says. The biggest challenge? "You have to figure out how to keep them suspended," he says. "They'll stick to the sides of the display if you let them, and degrade. So we had to make a small exhibit space seem like the open ocean."
Wyatt used yards of everyday bubble wrap to line the various-size holding tanks used to grow the crown jellies. The soft bubble wrap also keeps the jellies from hurting themselves when they happen to bump up against the walls. In our exhibit spaces, Wyatt created water currents, called "gyres," to help keep the delicate jellies in the middle of the display.
Very few studies have been done on the crown jelly, so little is known about this species. In raising this jelly in captivity for display at the Aquarium, our aquarists found the species to grow at an extremely fast rate—from just a few millimeters to the size of a dime in two to three weeks.
The crown jelly is distinguished by its array of about 30 "spikes" emanating from the broad, circular bell. Eight stout mouth-arms and more than 100 long, tapering, pointed appendages spring from this pinkish-purple jelly's central stomach.
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.
The purpose of the crown jelly's appendages is still unknown, although scientists speculate that it uses them to capture food.