In the Sherlock Holmes tale "The Adventure of the Lion's Mane," Sir Arthur Conan Doyle left no doubt as to the pernicious nature of the jellyfish (although the clever title would mislead anyone unfamiliar with them).
Aside from the Lion's Mane Jellyfish (Cyanea capillata), other non-human culprits unmasked by the world's best-known sleuth include a "swamp adder" and, of course, a big dog. But Doyle attributed signally excruciating potency to the giant cnidarian (whose nematocyst-laced tentacles can outstretch a Blue Whale):
As he fell over, his Burberry, which had been simply thrown round his shoulders, slipped off, exposing his trunk. We stared at it in amazement. His back was covered with dark red lines as though he had been terribly flogged by a thin wire scourge. The instrument with which this punishment had been inflicted was clearly flexible, for the long, angry weals curved round his shoulders and ribs. There was blood dripping down his chin, for he had bitten through his lower lip in the paroxysm of his agony. His drawn and distorted face told how terrible that agony had been.
That was 1907, with Sir Arthur's bell-topped killer vaguely foreshadowing the kind of panic that Peter Benchley and Steven Spielberg's classic "Jaws" would spawn more than a half-century later.
Don't look now; but the narrative of the ravenous beasts is back. Unpopular anyways outside of Asian salads, the deceptively beautiful medusa is experiencing a return to scurrilousness.
So Smithsonian.com has revisited the question of a jellyfish scourge. In addition to offering an engaging boilerplate description of the animals that alone makes the piece worth reading, Abigail Tucker explores how many ill-tempered jellyfish is too many jellyfish:
All around the world, jellyfish are behaving badly—reproducing in astonishing numbers and congregating where they’ve supposedly never been seen before. Jellyfish have halted seafloor diamond mining off the coast of Namibia by gumming up sediment-removal systems. Jellies scarf so much food in the Caspian Sea they’re contributing to the commercial extinction of beluga sturgeon—the source of fine caviar. In 2007, mauve stinger jellyfish stung and asphyxiated more than 100,000 farmed salmon off the coast of Ireland as aquaculturists on a boat watched in horror. The jelly swarm reportedly was 35 feet deep and covered ten square miles.Nightmarish accounts of “Jellyfish Gone Wild,” as a 2008 National Science Foundation report called the phenomenon, stretch from the fjords of Norway to the resorts of Thailand. By clogging cooling equipment, jellies have shut down nuclear power plants in several countries; they partially disabled the aircraft carrier USS Ronald Reagan four years ago. In 2005, jellies struck the Philippines again, this time incapacitating 127 police officers who had waded chest-deep in seawater during a counterterrorism exercise, apparently oblivious to the more imminent threat. (Dozens were hospitalized.) This past fall, a ten-ton fishing trawler off the coast of Japan capsized and sank while hauling in a netful of 450-pound Nomura’s jellies.
So there's a lot of anecdotal and circumstantial evidence of mounting jelly hell. But disabling and overturning ships? Not even Spielberg depicted his Great White Antihero crippling an aircraft carrier. (That wouldn't come until "Jaws 2.")
But before you go get a bigger boat, Mr. Mundus, it's important to read on. Tucker is quick to quote experts who say the jury is still out on this possible pestilence and its likely causes, which predictably include human encroachment on their habitat and devastation of the jellyfish's natural enemies (like swordfish, anchovies, bearded gobies, and some sea turtles).
Steven Haddock, a zooplankton scientist at the Monterey Bay Aquarium Research Institute (MBARI), is concerned that researchers and the news media may be overreacting to a few isolated jelly outbreaks. Not enough is known about historical jelly abundances to distinguish between natural fluctuation and long-term change, he says. Are there really more of the creatures, or are people simply more prone to notice and report them? Are the jellyfish changing, or is our perspective? A self-described “jelly hugger,” Haddock worries that jellyfish are taking the blame for messing up the seas when we’re the ones causing the damage. “I just wish that people had the perception that jellyfish are not the enemy here,” Haddock says.Purcell, who sports jellyfish earrings the day I meet her in Monterey, says she is disgusted by what she sees as humanity’s efforts to exploit the ocean, filling it with fish farms and oil wells and fertilizer. Compared with fish, jellies are “better feeders, better growers, more tolerant of all kinds of things,” she told me, adding of the marine environment: “I think it’s entirely possible we’ve made things better for jellyfish.” Part of her likes the idea of unruly jellies causing a commotion and foiling our plans. She’s cheering for them, almost.
So it's not a direct link, but generally, it looks like the worse damage we inflict on our seas, the more we can expect jellyfish to come back and sting us. A GlobalPost headlined "The New Ocean Predator: Jellyfish?" articulated the problem this way:
Unlike sharks, orcas and other aggressive carnivores, jellyfish thrive in ecosystems damaged by human activity. From the Gulf of Mexico to the Sea of Japan, oceanographers have found a common symptom among places where overfishing, chemical pollution and rising sea temperatures have killed off other species: more jellyfish.
Jellyfish are hardy indeed. Their fossil remains date back some 500-700 million years. As polyps, they can "sit dormant for a decade or more, biding (their) time," Tucker tells us. Their sting, at 1 microsecond to hit its target, is one of the fastest animal actions in the world. When turtles or other predators chomp off hunks of jellyfish, the animals simply regenerate. The arctic Lion's Mane "continues to pulsate when half its bell is imprisoned in ice, and may revive even after being solidly frozen for hours," Rachel Carson tells us. And on and on.
While technically speaking they're sophonophores rather than "true jellies," the Portuguese Man-of-War (Physalia physalis) is a jellyfish in most people's minds. And Carson suggested after one encounter that it demonstrated a "strong illusion of sentience":
The sail, or float, of a Portuguese man-of-war is filled with gas secreted by the so-called gas gland. The gas is largely nitrogen (85 to 91 per cent) with a small amount of oxygen and a trace of argon. Although some siphonophores can deflate the air sac and sink into deep water if the surface is rough, Physalia apparently cannot. However, it does have some control over the position and degree of expansion of the sac. I once had a graphic demonstration of this when I found a medium-size man-of-war stranded on a South Carolina beach. After keeping it overnight in a bucket of salt water, I attempted to return it to the sea. The tide was ebbing; I waded out into the chilly March water, keeping the Physalia in its bucket out of respect for its stinging abilities, then hurled it as far into the sea as I could. Over and over, the incoming waves caught it and returned it to the shallows. Sometimes with my help, sometimes without, it would manage to take off again, visibly adjusting the shape and position of the sail as it scudded along before the wind, which was blowing out of the south, straight up the beach. Sometimes it could successfully ride over an incoming wave; sometimes it would be caught and hustled and bumped along through thinning waters. But whether in difficulty or enjoying momentary success, there was nothing passive in the attitude of the creature. There was, instead, a strong illusion of sentience. This was no helpless bit of flotsam, but a living creature exerting every means at its disposal to control its fate. When I last saw it, a small blue sail far up the beach, it was pointed out to sea, waiting for the moment it could take off again. (p. 150 "The Edge of the Sea")
Now, she's not claiming that Portuguese Man-of-Wars would recognize themselves in a mirror or blush at buying their clothes off the rack. However, it's not an inconceivable leap from setting a course in the wind to stinging a bather just to watch him die.
Maybe Sherlock Holmes was onto something. A jellyfish strikes again in that story, after all. But no one's saying it's the same Lion's Mane, right? Right!?