The Jellyfish Are On the Move: Apocalypse Soon

Once in a very great while one encounters an article that is so startling, so fascinating, and so scary that it is necessary to go back over it to make sure that someone isn’t playing a joke. I encountered such a piece in the New York Review of Books by Tim Flannery: They’re Taking Over! Who is the "they?" Jellyfish!

The story Flannery tells is extracted from a book by Lisa-ann Gershwin: Stung! On Jellyfish Blooms and the Future of the Ocean. Gershwin has spent a good portion of her life studying jellyfish.

Jellyfish are perhaps the oldest species of marine animal. They are thought to predate the Cambrian era when nature went wild experimenting with new types of creatures. Given half a billion years of evolution, they exist in many different forms and they have learned how to survive in much more hostile environments than exist today. The theme of Gershwin’s book is that as we upset the delicate balance in the marine ecosystem by overfishing, polluting, and changing the chemistry of the oceans, we are creating an environment where jellyfish can thrive at the expense of other species.

By eliminating or diminishing jellyfish predators, lowering the oxygen level, and raising the acidity level in our oceans, we are creating conditions that are difficult for many species, but leave jellyfish relatively unaffected. Flannery includes this quote from the book:

"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."

Shellfish seem to have a dim future. Acidity rises as more carbon dioxide is absorbed into the water.

"Already our oceans are 30 percent more acidic than they were thirty years ago, and creatures with shells are suffering. In recent years, there has been mass failure of oyster spawning off the American Northwest, and tiny snails in the Arctic and Antarctic oceans are having their shells eaten away by the acid. Jellyfish lack hard parts: they, it seems, will pull through the acidification crisis admirably."

Jellyfish are also designed to survive in the oxygen-poor environment we are creating in our oceans.

"Jellyfish are almost ubiquitous in the oceans. As survivors of an earlier, less hospitable world, they can flourish where few other species can venture. Their low metabolic rate, and thus low oxygen requirement, allows them to thrive in waters that would suffocate other marine creatures. Some jellyfish can even absorb oxygen into their bells, allowing them to "dive" into oxygen-less waters like a diver with scuba gear and forage there for up to two hours."

Jellyfish unleashed make a formidable foe. The box jellyfish, native to the waters around Australia, is referred to as the "most venomous creature on earth."

"Box jellyfish have bells (the disc-shaped "head") around a foot across, behind which trail up to 550 feet of tentacles. It’s the tentacles that contain the stinging cells, and if just six yards of tentacle contact your skin, you have, on average, four minutes to live—though you might die in just two."

"Most jellyfish are little more than gelatinous bags containing digestive organs and gonads, drifting at the whim of the current. But box jellyfish are different. They are active hunters of medium-sized fish and crustaceans, and can move at up to twenty-one feet per minute. They are also the only jellyfish with eyes that are quite sophisticated, containing retinas, corneas, and lenses. And they have brains, which are capable of learning, memory, and guiding complex behaviors."

And then there is the nasty little jellyfish known as Irukandi, an Aboriginal word.

"The Irukandjis are diminutive relatives of the box jellies. First described in 1967, most of the dozen known species are peanut- to thumb-sized. The name comes from a North Queensland Aboriginal language, the speakers of which have known for millennia how deadly these minuscule beings can be."

"It’s now known that the brush of a single tentacle is enough to induce "Irukandji syndrome." It sets in twenty to thirty minutes after a sting so minor it leaves no mark, and is often not even felt. Pain is initially focused in the lower back. Soon the entire lumbar region is gripped by debilitating cramps and pounding pain—as if someone is taking a baseball bat to your kidneys. Then comes the nausea and vomiting, which continues every minute or so for around twelve hours. Shooting spasms grip the arms and legs, blood pressure escalates, breathing becomes difficult, and the skin begins to creep, as if worms are burrowing through it. Victims are often gripped with a sense of "impending doom" and in their despair beg their doctors to put them out of their misery."

Jellyfish really are on the move—including Irukandi.

"....Irukandji have recently been detected in coastal waters from Cape Town to Florida."

What makes jellyfish a worldwide problem is their efficiency in reproduction. Consider the specimen known as Mnemiopsis.

"One of the fastest breeders of all is Mnemiopsis. Biologists characterize it as a ‘self-fertilizing simultaneous hermaphrodite,’ which means that it doesn’t need a partner to reproduce, nor does it need to switch from one sex to the other, but can be both sexes at once. It begins laying eggs when just thirteen days old, and is soon laying 10,000 per day. Even cutting these prolific breeders into pieces doesn’t slow them down. If quartered, the bits will regenerate and resume normal life as whole adults in two to three days."

Jellyfish eggs hatch as polyps that attach themselves to hard surfaces. These polyps then proceed to produce a stream of jellyfish.

"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."

Jellyfish do not make good neighbors. They are voracious eaters with apparently unlimited appetite.

"Mnemiopsis is able to eat over ten times its own body weight in food, and to double in size, each day. They can do this because they are, metabolically speaking, tremendously efficient, being able to put more of the energy they ingest toward growth than the more complex creatures they compete with. And they can be wasteful. Mnemiopsis acts like a fox in a henhouse. After they gorge themselves, they continue to collect and kill prey. As far as the ecosystem goes, the result is the same whether the jellyfish digest the food or not: they go on killing until there is nothing left. That can happen quickly."

For those who are not yet worried about the effects of uncontrolled jellyfish population growth, consider what occurred when Mnemiopsis infiltrated the Black Sea.

"Would you believe, Gershwin asks, that ‘a mucosy little jellyfish, barely bigger than a chicken egg, with no brain, no backbone, and no eyes, could cripple three national economies and wipe out an entire ecosystem’? That’s just what happened when the Mnemiopsis jellyfish (a kind of comb jelly) invaded the Black Sea. The creatures arrived from the east coast of the US in seawater ballast (seawater a ship takes into its hold once it has discharged its cargo to retain its stability), and by the 1980s they were taking over. Prior to their arrival, Bulgaria, Romania, and Georgia had robust fisheries, with anchovies and sturgeon being important resources. As the jellyfish increased, the anchovies and other valuable fish vanished, and along with them went the sturgeon, the long-beloved source of blini toppings."

"By 2002 the total weight of Mnemiopsis in the Black Sea had grown so prodigiously that it was estimated to be ten times greater than the weight of all fish caught throughout the entire world in a year. The Black Sea had become effectively jellified."

If jellyfish can destroy that ecosystem, they can destroy others. The term "jellification" is not as bizarre as it sounds.

"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. The curtain is formed of jelly extruded by the creatures, and it includes stinging cells. The region once supported a fabulously rich fishery yielding a million tons annually of fish, mainly anchovies. In 2006 the total fish biomass was estimated at just 3.9 million tons, while the jellyfish biomass was 13 million tons."

Gershwin believes we have passed some point of no return with respect to our oceans. They will evolve to an unknown, but definitely undesirable state. Flannery provides her final thoughts.

"When I began writing this book,… I had a naive gut feeling that all was still salvageable…. But I think I underestimated how severely we have damaged our oceans and their inhabitants. I now think that we have pushed them too far, past some mysterious tipping point that came and went without fanfare, with no red circle on the calendar and without us knowing the precise moment it all became irreversible. I now sincerely believe that it is only a matter of time before the oceans as we know them and need them to be become very different places indeed. No coral reefs teeming with life. No more mighty whales or wobbling penguins. No lobsters or oysters. Sushi without fish."

Her advice to humanity:

"Adapt."

All of this may seem a bit overwrought. However, in the grand sweep of the earth’s history it has often become a rather hostile place for life. There have been several instances that have risen to the category of "mass extinctions." The most severe episode occurred about 250 million years ago and earned itself the title "The Great Dying."

"’The Great Dying was the biggest of all the mass extinctions,’ said study researcher Darcy Ogden of the Scripps Institution of Oceanography in San Diego. ‘Estimates suggest up to 96 percent of all marine species and 70 percent of all land species were lost’."

Who knows? Perhaps what we are facing is the second edition of "the revenge of the jellyfish."

It is good to encounter articles like this occasionally. They give one something to worry about when they grow weary of worrying about the economy.