Ecology: Cotylorhiza Tuberculata

The Greek Jellyfish – Cotylorhiza C. Tuberculata

Posted Portes Magazine ECOLOGY
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Kingdom: Animalia | Phylum: Cnidaria | Class: Scyphozoa | Order: Rhizostomeae | Family: Cepheidae | Genus: Cotylorhiza | Species: C. tuberculata


The Mediterranean Sea boasts a myriad of fascinating creatures. One of the most elaborate and graceful is the Cotylorhiza tuberculata, commonly known as the “καφετιά μέδουσα,” “fried egg jellyfish,” or Mediterranean jellyfish. The scientific name Cotylorhiza is a combination of two Greek words: “κοντύλι,” meaning cup, and “ρίζα,” meaning root. Its characteristic brown dome top, yellow skirt, and bright purple tentacles make it an easy sighting against the deep blue hue of Greek waters.

A typical adult C. tuberculata usually measures 17 to 20 centimeters wide, though they can reach 50 centimeters across. The jellies mainly feed on zooplankton, tiny organisms that drift with the water. Jellyfish reproduce asexually. Larva attach themselves to a hard ocean surface and grow in a polyp colony that looks like a stack of saucers. Tiny baby jellyfish are then released from capsules like spaceships and drift away.

“Swimmers should not freak out, they’re very graceful, you can swim around them and have great fun.” – Dr. Peter Nicolaides

With their alien-like appearance, jellyfish are notorious for their stinging nature and often dreaded by humans and other sea creatures alike. “All these creatures sting you with a very clever mechanism called a nematocyst,” explains Dr. Peter Nicolaides, a marine biologist-oceanographer with the Aegean Institute, a Paros-based diving college. “As soon as you brush against the spike on the tentacle area, it triggers out an infolded whip that causes tiny lacerations in the skin and releases a little bit of poison.”

But the C. tuberculata’s touch, he says, is relatively harmless to both humans, and the juvenile mackerel fish which dart in and out of the jelly mass. “It’s a floating safe house for them…it moves around with the planktonic drift and the mackerel have a chance,” Dr. Nicoladies says. “C. tuberculata are very elegant creatures.” Little is known about what leads to population explosions of jelly fish, but researchers attribute this phenomenon to favorable circumstances in the ecosystem. “It’s like a sort of red tide…when the conditions are right you have a bloom,” he says. The sight of a medusa swarm can be breathtaking, as these docile creatures float graciously onward. “Many years ago there were huge populations of jelly fish in general and the tourist organization got worried,” recalls Dr. Nicolaides. “And then the next year there was nothing.”

One of C. tuberculata’s natural predators is the Caretta caretta, a sea turtle and favorite sighting among tourists and marine enthusiasts. “The turtles love it, they go bananas for the medusa,” Dr. Nicolaides says. Luckily, C. tuberculata is not in immediate danger of disappearance, unlike the Caretta caretta. Yet, they are still important in the balance of sea life. “An ecosystem is a perfect class for management. You have all these components that are interconnected…the more biodiversity there is, the more stable the system is,” says Dr. Nicolaides. “Oligopolies are the worst thing.”

While C. tuberculata would not make for a good aquarium pet, these creatures make themselves easily accessible in their natural habitat, peacefully drifting along with the ocean’s flow. Dr. Nicolaides, who has spent years observing sea life, is very fond of the non-stinging C. tuberculata. “Swimmers should not freak out, they’re very graceful, you can swim around them and have great fun,” he says.

Take a look at the Greek jellyfish up close here.