Growing concern over lion’s mane jellyfish sightings

A purported lion’s mane jellyfish.

SWAMPSCOTT — There is a growing concern among residents about the increased sightings of lion’s mane jellyfish, with at least two reports of potential stings in Swampscott over the weekend. 

The lion’s mane jellyfish is the largest species of jelly, with tentacles that can grow up to 120 feet long. Over the past month, sightings at Massachusetts beaches have increased, prompting the state’s Department of Conservation and Recreation to issue “purple flag warnings” at times in Swampscott, Lynn, and Nahant, letting swimmers know a potentially dangerous animal is in the waters. 

The lion’s mane jellyfish stings with its tentacles. Although stings are not thought to be fatal, they can be quite painful. 

On Sunday, Swampscott resident Melissa Weinand was at Eisman’s Beach with her husband and their two sons, ages 4 and 6, who were playing in water at about chest height. Her four-year-old suddenly “popped up and started screaming,” before her husband ran to retrieve him from the water.

“He was covered in these tentacles that were wrapped around his belly and around his body all the way up to his face,” Weinand said. 

Weinand said her husband carefully removed the “many” tentacles and the family rushed back to their nearby home to pour vinegar on the boy’s wounds — vinegar is a recommended solution, including by New England Aquarium, for alleviating the pain from stings, but water should not be poured on stings, and the vinegar should not be rubbed onto the wounds. 

After about 10 to 15 minutes, the pain subsided, Weinand said, and her son is back to feeling normal. However, it was a frightening experience for the family that has lived in the area for over six years and never heard of the lion’s mane jellyfish before this summer. 

“When my husband took the tentacles off of him, and even after putting the vinegar on, it looked like my son had been whipped,” Weinand said. “He had these raised, red markings.”

Weinand said her son’s friend was also stung this past weekend. Another Swampscott resident, who did not wish to be named, said her son was stung by what seemed like “floating pieces” of tentacles in the water on Saturday. 

Town Administrator Sean Fitzgerald said Sunday that the town’s Health Department “has been evaluating the situation,” but said people should not be scared to go in the water.  

“We urge folks to be cautious and aware of the risks, but we want folks to enjoy the waterfront and the beaches,” Fitzgerald said. 

For the past month, sightings of lion’s mane jellyfish have increased. On June 9, the town put out an advisory on its official Facebook page reminding residents no swimming is allowed off the pier at Fisherman’s Beach, a regulation now “even more important than usual as there have been sightings of lion’s mane jellyfish, which can sting and cause bodily harm.”

Swampscott Board of Health Chairwoman Marianna Hartmann wrote there had been reported sightings not only near the pier, but at other beaches in town as well. 

Swampscott residents have also been posting photos on the Facebook community group Swampscott 01907 of lion’s mane jellyfish washed up on beaches, with one having a body the diameter of “a dinner plate.”

In response to the increase in sightings, nonprofit group The Swampscott Conservancy has begun working on a public service announcement for residents, and the group asks any video of lion’s mane jellyfish in the water be sent to

Bigelow Laboratory for Ocean Sciences, a marine biology research institute based in Maine, has also been collecting reports on lion’s mane jellyfish sightings as part of its research into why the sightings have increased. Fill out a report at



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