Clinging jellyfish are showing up in more New Jersey waters, and that has scientists worried.
The dime-size species, Gonionemus vertens, packs one heck of a sting — one that will most likely send victims to the hospital.
"This is the first year we've seen them in Barnegat Bay," said Paul Bologna, director of marine biology and coastal sciences at Montclair State University.
Earlier this month, about 40 clinging jellyfish were confirmed in north-central Barnegat Bay, on the bay side near Island Beach State Park, a popular watercraft area. The find prompted an advisory by the New Jersey Department of Environmental Protection.
Already this year, two men who were stung by clinging jellyfish were sent to the hospital, said Bologna. The pain begins with the "pins and needles" most jellyfish inflict. But it never subsides and builds to become excruciating, Bologna said.
"A couple hours later, people end up in hospital in incredible pain," he said.
Clinging jellies have a distinctive orange-brown cross on their transparent bodies. They get their "clinging" name because the sticky pads on their tentacles allow them to anchor onto sea grasses and seaweed.
Fortunately for beach-goers, they prefer calm, shallow water with plenty of sea grass and generally avoid the surf.
Clinging jellyfish, which are native to coastlines of the Pacific and Atlantic Oceans, especially near Vladivostok, Russia, and the Sea of Japan, are not new to the United States.
They first appeared along the East Coast near Cape Cod, Mass., and Groton, Conn., in 1894. But they nearly vanished in the 1930s after an eelgrass die off, according to the Woods Hole Oceanographic Institution.
Biologists first spotted adult clinging jellyfish in New Jersey in summer 2016 in the Shrewsbury, Metedeconk, and Manasquan Rivers in North Jersey. They are thought to have been carried to New Jersey by ships from New England or in the discharged ballast water of a ship from Asia.
"Any time you have an invasive species, there are more questions than answers," said Bologna, who operates the Facebook page New Jersey Jellyspotters, where people can post photos of jellies and get proper identification. Montclair State and the DEP have been working together to locate the jellies.
But finding their haunts in order to study them can be tricky. "They are just bloody teeny," said Bologna.
"The only way to get rid of them is to know how to get rid of the polyps," Bologna said about one of the developmental stages of the jellyfish.
Clinging jellyfish are not the only venomous sea creatures making a return to the Jersey Shore this summer. The Portuguese man-of-war was recently spotted in Wildwood.
After Hurricane Sandy, sea nettles — a common local jelly with a more mild sting that is known to feast on other non-native jellies — took a hit.
"They were the top predators," said Bologna. "All other species now can bloom and grow."
"I'd take a sea nettle over a clinging jelly any day of the week," said Bologna.
To avoid a clinging jellyfish sting, the DEP suggests that anyone wading in shallow areas near vegetation wear protective boots.
If stung by a clinging jellyfish, the DEP recommends: