I do believe Jellyfish and algae are buddies and a food source for each other. Click here to read the full article or an excerpt below.
Mastigias have evolved to rely on a distinctive partnership for their nutrition. They have a symbiotic relationship with single-celled marine algae. Inside the tissues of Mastigias’ frilly arms live millions of single-celled algae called zooxanthellae, which use solar energy to convert carbon dioxide and solar energy into carbohydrates that the jellyfish use for energy.
The lake-bound jellyfish migrate across the lake and back during the day, swimming continuously. Scientists believe this is for two reasons: to keep their zooxanthellae in the light, and to avoid the shadows that form at the lake edges, where Mastigias’ predators (bottom-living sea anemones) live. At night, the Mastigias stop moving horizontally and swim up and down in the lake, away from the edges. Scientists have suggested that the nightly trips might provide the algae with essential nutrients available only in deeper water.
Studying Mastigias’ movementsin Jellyfish Lake, Kakani Katija, now a postdoctoral scholar at WHOI, has proposed that swimming jellies, moving up and down en masse, could play an ecologically significant, previously unsuspected role in mixing stratified layers of water within the ocean. Her work was published in 2009 in the journal Nature.
“There’s no ecosystem like Jellyfish Lake in the world,” she said. “This is a great place to see how the jellyfish affected mixing in the lake, because there’s much less wind and tidal motion affecting the water than in the ocean, so you can isolate the effect of the jellies.”
WHOI Director of Research Larry Madin (whose doctoral adviser William Hamner was one of the first to describe the Mastigias migration) studies jellyfish and other gelatinous ocean animals, from the Antarctic to the tropics.
“These Mastigias are beautiful and hypnotic,” he said, “and they also offer a remarkable lesson in how animals and ecosystems adapt and evolve.” Interestingly, the Mastigias in each of Palau’s five jellyfish lakes, though the same species, all look different from each other and from Mastigias in the nearby ocean. The jellyfish in all five lakes have zooxanthellae, but each lake’s jellyfish may depend on its symbiotic algae for nutrition to a different degree.