Jellyfish canal. Cilia in these canals circulate the fluid in a regular direction. The box jellyfish is largely similar in structure. It has a squarish, box-like bell from each of the four lower corners of which hang a short pedalium or stalk which bears one or more long, slender tentacles. The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates, allowing box jellyfish to swim faster than true jellyfish. Hydrozoans are also similar, usually with just four tentacles at the edge
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.