The Blue jellyfish, known scientifically as Cyanea lamarckii, is similarly shaped to the Lion’s Many jelly with its bell shape and dense, trailing tentacles. However, unlike the Lion’s Mane, the Blue jellyfish is born pale and grows to be a striking blue color as it matures. The Blue jellyfish is also smaller than the Lion’s Mane. Preferring the open ocean, the Blue jellyfish can usually be spotted floating around the U.K. coast, the North Sea, the Irish Sea, the English Channel, along Scotland’s west coast in summer and autumn. The Blue jellyfish lives for less than a year.