The Age of Jellyfish

The age of men is over. The time of the jellyfish has come.

From Spain to Uruguay, reports of increases in the number of jellyfish showing up at beaches is commonplace. The effect on tourism in Spain this summer has been widely noted. Some have been calling it "the year of the jellyfish." 

It might be more correct to view this as the dawning of a new age. Say hello to the soon-to-be dominant life-form that replaces us.

Jellyfish are interesting creatures, from the immortal variety, to the lion's mane jellyfish which can reach 36.5 metres (120 ft) in length, to the Nomura's jellyfish that can weigh 200 kilograms (440 lb). 

Jellyfish Lake, located on Eil Malk island in Palau, has a deep water anoxic layer that is poisonous to snorkelers or divers, as the hydrogen sulfide toxin present at about 15 to 20 meters can be absorbed through the skin. Yet the two species of jellyfish that thrive there seem to have found a way to turn this 'zone of death' to their advantage.

The golden jellyfish, for example, rise to the surface of the lake by day, exposing the symbiotic algae that reside within them to sunlight, then descend to the depths by night. Hovering just above the deadly layer, the algae now benefit by absorbing nutrients from the hydrogen sulfide-tolerant bacteria that dwell there.

Hydrogen sulfide is known as a broad-spectrum toxin. It was used by the British as a chemical warfare agent in WWI, and has an effective lethality comparable to carbon monoxide or hydrogen cyanide.

It is an effective killer of plants and animals, and is considered a top contender for the cause of the Permian-Triassic extinction event  that occurred 252 million years ago.  Theoretically, slowing ocean currents and ocean mixing, already triggered by a warming climate, could result in a dynamic very similar to that of jellyfish lake.  In fact, oceanic hydrogen sulfide emissions have already been detected in various regions around the globe, and especially off the coast of Namibia.

The current abundance of jellyfish in the world's oceans may simply be part of a 20-year cycle of blooms and declines. Or, we just might want to ask ourselves what life forms will be likely to dominate the oceans of a dying world.