Cyanea is a genus of jellyfish, primarily found in northern waters of the Atlantic and Pacific Oceans and southern Pacific waters of Australia[1] and New Zealand, there are also several boreal,[2] polar, tropical and sub-tropical species. Commonly found in and associated with rivers and fjords.[3][4][5][6][7][8][9][10][11][12][13][14][15][16] 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).[17]
The taxonomy of Cyanea species has seen increased scrutiny in recent years.[1][18][2] Early zoologists suggested that all species within the genus should be treated as one.[19][20] Recent molecular and integrative taxonomic studies have refuted this assertion[1][21][22] as the scyphozoan community has restored many of the previous species.[23] For example, in the North Sea, the lion's mane jellyfish and the blue jellyfish appear as distinct species.[24] On the East Coast of the United States there are at least two co-occurring species, C. fulva and C. versicolor.[25] Cyanea may be a species complex of recently diverged species.