Biologists and environmental groups are monitoring an invasive jellyfish with a painful sting that has spread into Vineyard waters in recent years.

Little is known about how the clinging jellyfish (Gonionemus), named for the sticky pads on the ends of its 80 tentacles, made it to the Island.

Clinging jellyfish (Gonionemus) named for the sticky pads on the ends of its 80 tentacles. — Ray Ewing

Sightings have been confirmed in Farm Pond, Lake Tashmoo, Sengekontacket Pond, Squibnocket Pond and Stonewall Beach.

“They’re liking it here,” Edgartown shellfish constable Paul Bagnall said last week after a scientist from the Woods Hole Oceanographic Institution traveled to the Vineyard to examine some of the creatures found in the Edgartown Great Pond. “We don’t have the understanding of their life cycle enough to try and interrupt it.”

The jellyfish are difficult to spot because of their small size, translucence and earthy color that allows them to camouflage within their surroundings, according to WHOI researcher Mary Carman, who has co-authored scientific papers on clinging jellyfish. The creatures are roughly the size of a dime and have a prominent cross on their body.

Ms. Carman said there are toxic and nontoxic types within the species. She said both are Gonionemus jellies and require DNA samples to differentiate. The only way to be sure is to be stung, a painful and potentially dangerous experience.

“It’s similar to a bee sting,” said Mr. Bagnall. “Except you’re not getting stung by one bee, you’re getting the swarm going down your arm.”

The first clinging jellyfish in the region were recorded in Eel Pond in Woods Hole in the 1890s. The first sting was reported in 1990. In 2015, the jellyfish were reported on Island congregating near eelgrass beds in Farm Pond.

Oak Bluffs shellfish constable Dave Grunden said he has seen the population grow dramatically in recent years, particularly in Farm Pond.

Last summer, Mr. Grunden put out a net in the pond and found about 300 in under an hour. He left with a sting on his lip and finger.

Emily Reddington (left) and Mary Carmen. — Ray Ewing

“Not the way you want to discover things,” he said.

Last month there were two unconfirmed sightings of the jellyfish in the Edgartown Great Pond, one during water sampling by the Great Pond Foundation.

The jellyfish are more typically found in a higher-salinity environment, but Ms. Carman said polyps could have attached to the bottoms of boats.

Emily Reddington, director of science and education for the foundation who has done field research with Ms. Carman, suggested that they could have entered the pond when the pond was cut to the sea — an event that is done about four times a year.

“A lot of new species get introduced to the pond when the water is refreshing,” Ms. Reddington said. “Just like how things go from the pond into the ocean, things from the ocean come into the pond.”

Mr. Bagnall chalks up the influx to warmer waters caused by climate change. He said other invasive aquatic species like the green crab have been moving north and into Vineyard waters in recent years due to the higher ocean temperatures.

“Through time we mix the good and the bad through all the seven seas,” the longtime biologist said.

Last week Ms. Carman and Ms. Reddington took a small skiff out on the Great Pond and found a group of jellyfish while snorkeling along the shore of Kanomika Point. Three were taken for further study at WHOI.

“These guys like protected, quiet backwaters,” said Ms. Carman. “They’re very established on the Vineyard now. It’s clear we need to monitor them over the next few years.”

For swimmers, kayakers and snorkelers wanting to avoid being stung, Mr. Grunden suggested staying away from eelgrass beds.

“They cling to eelgrass blades and when disturbed, swim to the surface,” he said.

Ms. Reddington agreed.

“Don’t wade or swim into aquatic vegetation in the Great Pond right now,” she said. “We don’t want to scare people, but inform them.”