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State officials warn beachgoers about lion’s mane jellyfish

A lion's mane jellyfish floated in the water at Scituate Harbor in June 2020.
A lion's mane jellyfish floated in the water at Scituate Harbor in June 2020.John Tlumacki/Globe Staff

State officials are warning beachgoers to be on the lookout for lion’s mane jellyfish in the waters off Nahant, Quincy, Hull, and Boston.

The Department of Conservation and Recreation issued an advisory stating that lion’s mane jellyfish had been seen at Nahant Beach Reservation, Wollaston Beach, and Carson Beach in South Boston. DCR officials issued a similar warning on June 4 due to recent sightings of lion’s mane jellyfish at Nantasket Beach in Hull.

The agency on Wednesday also posted purple flags at those beaches to warn the public about the presence of the jellyfish, which are known for delivering painful stings.


The tentacles of lion’s mane jellyfish can exceed 100 feet in length.

In New England waters, a typical lion’s mane jellyfish has a translucent, saucer-shaped bell that’s about 10 to 12 inches wide and tentacles trailing up to 20 feet long. But larger ones have been known to wash up on local shores, some with bells measuring several feet wide and tentacles of up to 40 to 50 feet.

Hull officials recently posted some tips for beachgoers on the town’s emergency management notifications system’s Facebook page.

“If you do see one, exit the water and give it plenty of room to avoid those long stinging tentacles,” Deputy Fire Chief William Frazier wrote in the Facebook post. “If you come upon one washed up on the sand, do not attempt to move it, the tentacles can be very difficult to see and some jellyfish can still sting while out of the water.”

Chris Doller, the supervisor of changing exhibits at the New England Aquarium and the aquarium’s resident jellyfish expert, said smaller lion’s mane jellyfish have been spotted in the water outside of the aquarium.

“They’re definitely starting to show up,” he said. “They are local. They’re actually found from Maine down to Florida. They stretch up and down the coast.”


Last summer there was an uptick in lion’s mane jellyfish sightings. They were showing up in increasing numbers at Massachusetts beaches, but researchers could not explain why.

When asked whether climate change might result in larger populations of lion’s mane jellyfish, Doller said, “There’s no concrete evidence that it’s related or not. It is pretty cyclical.”

Emily Sweeney can be reached at emily.sweeney@globe.com. Follow her on Twitter @emilysweeney.