Box jellyfish box jellyfish's nervous system is more developed than that of many other jellyfish. They possess a nerve ring around the base of the bell that coordinates their pulsing movements, a feature found elsewhere only in the crown jellyfish. Whereas some other jellyfish have simple pigment-cup ocelli, box jellyfish are unique in the possession of true eyes, complete with retinas, corneas and lenses. Their eyes are set in clusters called rhopalia, located in pockets halfway up the outer, flat surfaces of the bell. Each contains two rhopalial ocelli with lenses, one directed upwards and the other downwards and inwards towards the
Cyanea (jellyfish) Cyanea (jellyfish) Cyanea is a cosmopolitan genus of stinging jellyfish, primarily found in northern waters of the Atlantic and Pacific Oceans. The same genus name has been given to a genus of plants of the Hawaiian lobelioids, an example of a "parahomonym" (same name, different kingdom). The taxonomy of "Cyanea" species is not fully agreed upon. Some zoologists have suggested that all species within the genus should be treated as one. However, in the North Sea at least, the lion's mane jellyfish and the blue jellyfish appear as distinct species. "Cyanea" may be a species complex of recently diverged species.