We are creating a world more like the late Precambrian than the late 1800s -- a world where jellyfish ruled the seas and organisms with shells didn't exist. We are creating a world where we humans may soon be unable to survive, or want to. [...]
Even sober scientists are now talking of the jellification of the oceans. And the term is more than a mere turn of phrase. Off southern Africa, jellyfish have become so abundant that they have formed a sort of curtain of death, "a stingy-slimy killing field," as Gershwin puts it, that covers over 30,000 square miles. [...]
Jellyfish reproduction is astonishing, and no small part of their evolutionary success: "Hermaphroditism. Cloning. External fertilization. Self fertilization. Courtship and copulation. Fission. Fusion. Cannibalism. You name it, jellyfish [are] 'doing it.'" But perhaps the most unusual thing is that their eggs do not develop immediately into jellyfish. Instead they hatch into polyps, which are small creatures resembling sea anemones. The polyps attach to hard surfaces on the sea floor, and are particularly fond of man-made structures, on which they can form a continuous jelly coating. As they grow, the polyps develop into a stack of small jellyfish growing atop each other that look rather like a stack of coins. When conditions are right, each "coin" or small jellyfish detaches and swims free. In a few days or weeks, a jellyfish bloom is observed. [...]
The question of jellyfish death is vexing. If jellyfish fall on hard times, they can simply "de-grow." That is, they reduce in size, but their bodies remain in proportion. That's a very different outcome from what is seen in starving fish, or people. And when food becomes available again, jellyfish simply recommence growing. Some individual jellyfish live for a decade. But the polyp stage survives pretty much indefinitely by cloning. One polyp colony started in 1935 and studied ever since is still alive and well in a laboratory in Virginia.
One kind of jellyfish, which might be termed the zombie jelly, is quite literally immortal. When Turritopsis dohrnii "dies" it begins to disintegrate, which is pretty much what you expect from a corpse. But then something strange happens. A number of cells escape the rotting body. These cells somehow find each other, and reaggregate to form a polyp.
They are turning OUR
atmosphere ocean into THEIR atmosphere ocean: