Purcell and a graduate student, Amanda Winans, decided to breed moon jellyfish in water with the staggering acid levels that some scientists say will prevail in the years 2100 and 2300. “We took it to very severe acid, using the worst predictions,” Purcell says. The jellyfish reproduced with abandon. She has also conducted experiments that lead her to suspect that many jellies reproduce better in warmer water.
With the world’s human population expected to increase 32 percent by 2050, to 9.1 billion, a number of environmental conditions that favor jellyfish are predicted to become more common. Jellyfish reproduce and move into new niches so rapidly that even within 40 years, some experts predict “regime shifts” in which jellyfish assume dominance in one marine ecosystem after another. Such shifts may have already occurred, including off Namibia, where, after years of overharvesting, the once fecund waters of the Benguela current now contain more jellyfish than fish.
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.
Widmer’s lab at the Monterey Aquarium is dominated by bubbling lime-green columns of algae, which he feeds to brine shrimp, which he then feeds to jellyfish. The algae come in six other “flavors,” but he says he prefers the green type for its mad scientist aesthetic. The room is full of jellyfish tanks ranging in size from salad bowls to wading pools. The containers rotate slowly, creating a current. “Let’s feed!” Widmer cries. He scrambles up and down stepladders, squirting a turkey baster of pink krill into this tank and that.
Toward the back of the lab, haggard orange sea nettles stumble along the bottom of their tank, their bells brownish and transparent, their tentacles torn. These, Widmer says, have been taken out of the public display and retired. “Retired” is Widmer’s euphemism for “about to be snipped up with fabric scissors and fed to other jellies.”
He calls his prize specimens “golden children.” He speaks to them in cooing tones usually reserved for kittens. One tank holds the petite but striking purple-lipped cross jellies, which Widmer retrieved from Monterey Bay. The species has never been bred in captivity before. “Oh, aren’t you cute!” he trills. The other golden child is a small brown smudge on a pane of glass. This, he explains, dabbing artistically at the smudge’s edges with a paintbrush, is a colony of lion’s mane jellyfish polyps.
When jellyfish sperm and egg meet, the fertilized egg forms a free-swimming larva, what Widmer describes as “a fuzzy ciliated tic tac.” It whizzes around before landing on a sponge or other seafloor fixture. There it morphs into a weedy little polyp, an intermediate form that can reproduce asexually. And then—well, sometimes nothing happens for a good long while. A jellyfish polyp can sit dormant for a decade or more, biding its time.
When ocean conditions become ideal, however, the polyp starts to “strobilate,” or bud off new jellyfish, a process Widmer shows me under a microscope. One polyp looks as if it is balancing a stack of Frisbees on its head. The tower of tiny discs pulses slightly. Eventually, Widmer explains, the top one will fly off, like a clay pigeon at a shooting range, then the next one, and the next. Sometimes dozens of discs launch, each disc a baby jellyfish.
To test the impact of warming oceans on polyp productivity, Widmer assembled a series of incubators and seawater baths. If he heated each a few degrees warmer than the last, what would the jellyfish do? At 39 degrees Fahrenheit, the polyps generated, on average, about 20 teeny jellyfish. At 46 degrees, roughly 40. The polyps in 54-degree seawater birthed some 50 jellies each, and one made 69. “A new record,” Widmer says, awed.
To be sure, Widmer has also found that some polyps can’t produce young at all if placed in waters significantly warmer than their native range. But his experiments, which confirm research on other jellies done by Purcell, also lend some credence to anxieties that global warming may induce jelly extravaganzas.