Jellyfish always much greater than the Lion's Mane, whose bell diameter can reach . The rarely encountered deep-sea jellyfish "Stygiomedusa gigantea" is another candidate for "largest jellyfish", with its thick, massive bell up to wide, and four thick, "strap-like" oral arms extending up to in length, very different from the typical fine, threadlike tentacles that rim the umbrella of more-typical-looking jellyfish, including the Lion's Mane. Jellyfish have a complex life cycle which includes both sexual and asexual phases, with the medusa being the sexual stage in most instances. Sperm fertilize eggs, which develop into larval planulae, become polyps, bud into ephyrae
Jellyfish ahypoxic (low in oxygen). This in turn kills fish and other animals, but not jellyfish, allowing them to bloom. Jellyfish populations may be expanding globally as a result of land runoff and overfishing of their natural predators. Jellyfish are well placed to benefit from disturbance of marine ecosystems. They reproduce rapidly; they prey upon many species, while few species prey on them; and they feed via touch rather than visually, so they can feed effectively at night and in turbid waters. It may be difficult for fish stocks to reestablish themselves in marine ecosystems once they have become dominated by