Aside from their small size and clear membrane, these stinging jellyfish are much like they’re portrayed in cartoons — aggressive swimmers with dangerous capabilities.
Clingers, scientifically known as gonionemus, earned their name with their affinity for adhering themselves to eelgrass and other vegetation in saltwater pond environments. “The stings occur when people disturb eelgrass,” Annette Govindarajan, a research specialist at Woods Hole Oceanographic Institution (WHOI), said. “They don’t swarm. They live in more quiet, protected areas, in saltwater ponds where there’s a lot of eelgrass.”
Like most jellyfish, clingers are not fond of high-energy environments, which means the beaches are clear, but the calm waters of Island ponds are a little more risky, as these coin-size creatures are known to pack a punch. In a few cases, clingers have landed people in the hospital for emergency treatment.
There’s little question that these jellyfish are understudied and overpopulated in Island ponds. Oak Bluffs shellfish constable David Grunden is currently working with biologists Mary Carman and Ms. Govindarajan from WHOI to remedy both issues.
After a day on Farm Pond collecting clingers for research, Ms. Carman told The Times, “Gonionemus seem to be in the greatest abundance I’ve ever seen; they’re very dense in Farm Pond.” Ms. Carman believes that the population will continue to grow unless a natural predator emerges. Furthermore, she is curious to study how these jellyfish interact with their environment. Ms. Carman has observed a clinger stinging a fish. “The fish immediately dropped to the seafloor. It’s possible they could have a negative impact on fish populations,” she said, pointing to the necessity for further research on the species.
Responding to a question on whether someone jumping into Farm Pond would get stung, Mr. Gruden said, “I think you probably would.” While Farm Pond is no destination for swimming, clingers are congregating in some of the more recreationally utilized ponds as well, including Sengekontacket Pond, Lake Tashmoo, Stonewall Pond, and Squibnocket Pond. In April, Ms. Govindarajan reassured The Times that the public shouldn’t feel too inclined to run for the sea, as the jellyfish tend to stick to the heavily vegetated areas — literally — where people are less likely to be anyway.
“We know that the stinging cells stay active after they’ve stung,” Mr. Grunden said, noting that he learned this the hard way, after touching his face during research. While Mr. Grunden experienced only minor, short-lived swelling, others have had more extreme reactions to clinger stings. In the same way that different people’s bodies react differently to bee stings, so goes it with clingers.
The clinger is currently classified as an invasive species from the northern Pacific. They were first documented in Woods Hole in 1894 by biologists. “They went away in the 1930s when there was an eelgrass blight, but in the past 15 to 20 years, we’ve been seeing them come back, and we’ve been getting reports of some pretty nasty stings,” Ms. Govindarajan told The Times.
Mr. Grunden said he found the first clinger in Farm Pond in 2006.
Ms. Carman has her own theories about the presence of gonionemus in Island waters. Research has shown that there are two types of these jellyfish, one that stings and another that does not, and they’re very hard to tell apart. As Ms. Govindarajan’s recent paper, published on PeerJ, suggests, these could be two different species of gonionemus.
The first news of local clinger stings arose in the 1980s. The toxic clingers are commonly found in Russia, whereas the benign clingers live on America’s West Coast. Ms. Carman is curious to learn whether or not the benign strain are in fact native to this region. The meeting of these two species on the East Coast inspired further questions for Ms. Carman and her colleagues, such as if these groups are interbreeding. If so, the fertility of the offspring could offer clarification about whether toxic and nontoxic clingers are the same species. Offspring of the same species should be fertile to sexually reproduce. “If they’re different species,” Ms. Carman said, “it may be similar to a mule, where offspring will be infertile.”
Clinger life cycle
Scientists know that the clingers live one summer as an adult before they die off in early autumn. Before they reach adulthood, they go through the microscopic larvae and polyp stages. It’s not known how long the polyp stage can last, but it is known that the polyp can form an outer shell so it can survive the New England winter. It’s likely that the clinger survived the eelgrass blight in the 1930s by hunkering down in the polyp stage.
“The polyp stage is interesting, because one polyp can make several jellyfish; it’s an asexual stage in their life cycle,” Ms. Govindarajan said. “The adults reproduce sexually, and they produce larvae, which form polyps, and the polyps in the asexual stage make the jellies,” she said. “When jellyfish occur in blooms, it’s because a polyp can make a lot of jellies, and a lot of polyps can make an awful lot of jellies.”
Although the jellyfish was first discovered in Woods Hole over a century ago, scientists have yet to determine what preys on clingers, and why an animal that feeds on small zooplankton has a sting so toxic it can temporarily paralyze humans.
In the past, researchers have speculated that degraded water quality may be a boon to clingers. “It’s more of a domino effect,” Ms. Carman clarified. “Excess nitrogen in the water leads to excess plants and phytoplankton, which provide the habitat and food sources of gonionemus in great amounts.”