Jellyfish sting Edgartown and Vineyard Haven swimmers

Portuguese man-of-war washes ashore on Lobsterville Beach.

A Portuguese man-o-war float washed up on Lobsterville Beach in Aquinnah. — Kaysea Cole Hart

Edgartown Harbor was mobbed with large pink and white jellyfish toward the end of last week and into the weekend, according to harbormaster Charlie Blair.

“They came in with the last northeast wind, and they were thick,” he said.

Blair said several swimmers in Edgartown waters received stings.

“In the water they looked about two feet,” Chappy Ferry captain Liz Villard said.

On Saturday, 9-year-old Jesse Lieber was swimming at Long Point in Edgartown when he felt stings, his father Jasper told The Times. “Suddenly Jesse was yelling, Ow, ow, ow,” he said.

Jesse was stung three or four times on the arm and once on the chin, his father said. “First it felt like a brush touching my arm, then it hurt a lot,” Jesse said.

Jesse received vinegar and benzocaine towelettes from Trustees of Reservations staff, but by then, he said, the pain was ebbing. After about 20 minutes it subsided. The stings left no marks, he said, and he never saw a jellyfish.

On Friday, two kids were stung at Owen Park Beach in Vineyard Haven, Tisbury harbormaster John Crocker said. A boy who Crocker estimated was in his early teens was stung on the hand and elsewhere while swimming. A girl, who Crocker guessed was about 8 years old, had been swimming out by the raft off the beach when she was stung. She climbed on the raft and had to be rescued by the lifeguard, Crocker said. Her stings were more numerous, and based on how she was faring after the stings, Crocker said he decided to dial for medical aid. Both the swimmers were taken by ambulance to the Martha’s Vineyard Hospital, according to Fire Chief John Schilling. Crocker said at no time did he see a jellyfish.

Larry Madin, deputy director and vice president for research at the Woods Hole Oceanographic Institution, spent many years researching jellyfish. He told The Times the lion’s mane jellyfish is among the most common locally, and is a possible suspect for recent encounters in Edgartown.

“That’s one we typically see in our waters,” he said.

In the North Atlantic, lion’s mane jellyfish can grow to 3 meters in diameter and trail hundreds of fine tentacles up to 30 meters long, Lisa-Ann Gershwin wrote in the 2016 book “Jellyfish: A Natural History.” However, based on the white and pink color descriptions, Madin said it was possible the hordes of jellyfish seen in Edgartown Harbor were Pelagia noctiluca, what he described as a more offshore species. The name means “drifting night light,” Gershwin wrote in her book. This jellyfish travels in swarms and has a “fierce sting,” Gershwin noted, but it is small, less than 7 centimeters in diameter.

A seasonal Aquinnah resident sent The Times a photograph of a bluish bladder found on Lobsterville Beach thought to be a Portuguese man-of-war. Madin reviewed the image and agreed it was the “float” of a man-of-war.

While related to jellyfish, Madin said the man-of-war is different in that it is not a single organism but an aggregation of individual creatures known as a siphonophore. The individual creatures are described as “persons” by Gershwin.

“It’s a colony, you might say; multiple mouths and stomachs,” Madin said.

The colony is buoyed by a float and drifts, he said. Ones found in Vineyard waters likely came up the Gulf Stream from where they are normally found off Florida, Georgia, and the Carolinas, he said.

Though notorious, men-of-war are not generally lethal, he said, but are extremely painful. He likened accidentally swimming into its mass of tentacles as “pretty similar to swimming into a wasp nest.”

In the daytime, men-of-war tend to contract their tentacles, he noted, but at night, when they feed on small fish, they can extend 10 to 20 feet away from the float.

Despite their tendency to draw their tentacles in during the day, Madin suggested swimmers give the floats a wide berth should they spot one while in the water.

Washed up on a beach, the colony’s tentacles can still sting, he warned. They only lose the capacity once they dry out.