Pelagia noctiluca are opportunistic and have been recorded feeding on a wide range of small organisms like planktonic crustaceans (cladocerans, copepods, ostracods and crustacean larvae), mollusk larvae, larvaceans, hydromedusae, siphonophorans, arrow worms, fish eggs and fish larvae, as well as detritus suspended in the open water and microscopic phytoplankton.

Car­niv­o­rous like other Cnidar­i­ans, this species preys mainly on zoo­plank­ton, small fish, crus­taceans, other jel­ly­fish, and eggs. Pela­gia noc­tiluca cap­tures its prey with ten­ta­cles armed with cnido­cytes, each of which con­tains a ne­ma­to­cyst. Ne­ma­to­cysts have barbed fil­a­ments to trap their prey and tox­ins to stun them.

P. noctiluca feeds primarily on macrozooplankton and spend most of their time searching for food. Like all jellyfish, they have stinging nematocyst cells which they use in food capture and defense. Their primary predators are fish.

Diet: Gelatinous organisms, planktonic crustaceans, fish eggs and larvae.

Examples of types of plankton consumed by this jellyfish include copepods (their favorite food), water fleas, eggs and larvae of crustaceans, fish and molluscs, smaller mauve stingers and even tiny phytoplankton (photosynthesizing plankton types like green algae and cyanobacteria).