Jellyfish restored: they eat fish eggs and juvenile fish, and compete with fish for food, preventing fish stocks from recovering. Some small fish are immune to the stings of the jellyfish and live among the tentacles, serving as bait in a fish trap; they are safe from potential predators and are able to share in the fish caught by the jellyfish. The cannonball jellyfish has a symbiotic relationship with ten different species of fish, and with the longnose spider crab, which lives inside the bell, sharing the jellyfish's food and nibbling its tissues. Jellyfish form large masses or blooms in certain
Helmet jellyfish Helmet jellyfish The helmet jellyfish ("Periphylla periphylla") is a luminescent, red-colored jellyfish of the deep sea, belonging to the order Coronatae of the phylum Cnidaria. It is the only species in the monotypic genus "Periphylla." "P. periphylla" represents an exception, very rarely found in the phylum "Cnidaria": the medusae do not go through a polyp stage, thus presenting a "holopelagic" life cycle. The medusae strew fertilized eggs in open water and these develop directly into medusae, whose development rests entirely upon the egg's high yolk supply. The ephyra stage common among other jellyfish is not observed in "P. periphylla". The