The New Jersey Department of Environmental Protection is reminding the public to be aware of clinging jellyfish, a small jellyfish capable of inflicting an extremely painful sting that is found in some bay and estuarine waters of New Jersey, including in the Metedeconk River, which serves as the northern border between Lakewood and Howell, and winds through Jackson and Brick.

In a statement today, the DEP said they continue to monitor the jellyfish populations, recently integrating a new testing technique that improves early detection capabilities through environmental DNA, or eDNA, markers in the water column.

“Fortunately, populations of clinging jellyfish and their distribution have been largely stable since the species was first confirmed in New Jersey in 2016,” Commissioner of Environmental Protection Shawn LaTourette said in a statement.

“However, clinging jellyfish pack such a potentially powerful sting that it is important for the public to be vigilant and take precautions when recreating in coastal bays and rivers where they are found,” he added.

It is highly unlikely for clinging jellyfish to be found in ocean waters or beaches in New Jersey. Rather, the species prefers shallow, slow-moving estuarine waters, where they attach themselves to algae or marine vegetation such as eel grass.

Clinging jellyfish range from the size of a dime to a quarter. Adults are marked by a distinctive reddish-orange to yellowish cross within their translucent bodies.

Clinging jellyfish are a non-native species that was first confirmed in New Jersey in 2016.

The species, native to the Pacific Ocean, likely was transported to the East Coast in ballast water from ships or being attached to ships’ hulls, perhaps as early as the late 1800s in New England. They can be found from Maine to New Jersey.

In New Jersey, clinging jellyfish populations are established in several locations including the Metedeconk River, the bayside of Island Beach State Park, the Shrewsbury River, a salt pond in North Wildwood located adjacent to Hereford Inlet Lighthouse, Lower Township Thorofare (a type of coastal waterway) and the Cape May National Wildlife Refuge.

The jellyfish are found from mid-May to late July, or until bay water temperatures reach or exceed 82 degrees Fahrenheit.

Adult clinging jellyfish prefer to be attached to eelgrass and seaweed during the day but become active in the water column if disturbed and after sunset. If disturbed, they will attempt to reattach to the substrate, which provides shelter and protection.

The public can find confirmed clinging jellyfish locations on the NJ Clinging Jellyfish Interactive Map. The map is updated weekly as research scientists from the DEP and Montclair State University continually monitor areas where the species are established and investigate reported sightings and places with suitable habitat.

To minimize chances of an encounter, the DEP urges the public to: 

• Avoid wading into areas where the species has been observed; clinging jellyfish attach themselves to algae and submerged aquatic vegetation such as seagrass.
• Reduce the risk of being stung by wearing waders and long-sleeved clothing in these waters.

Reactions to stings can vary from person to person. Those who are stung by a clinging jellyfish will experience an initial burning sensation.

If stung by a clinging jellyfish:

• Rinse the area with saltwater and remove any remaining tentacle materials using gloves, a plastic card or a thick towel.
• If symptoms persist or pain increases instead of subsiding, seek prompt medical attention.