Stinging, Clinging Jellyfish Return To Jersey Shore

NEW JERSEY — As beachgoers begin packing the Jersey Shore and wading in the river mouths and lagoons of the Barnegat Bay, they may not see the tiny stinging jellyfish that make their home there — but they sure will feel it if they get stung.

Clinging jellyfish have been spotted in Cape May and the Barnegat Bay already this year, according to posts on the online New Jersey Jellyspotters group.

Paul Bologna, a biology professor and the director of the Marine Biology and Coastal Sciences Program at Montclair State University, has been researching and monitoring the jellyfish for several years and posts updates on the Jellyspotters page. Bologna said that a captain with Skimmer Tours spotted the tiny jellies on the weekend of May 16, and that he saw them himself in the northern part of the bay that weekend.

The non-native species, which was first confirmed in New Jersey in 2016, delivers a powerful sting, and the presence of the jellyfish has been monitored since then by the state Department of Environmental Protection and by scientists at Montclair State University.

Monitoring in 2021 began in late May, but so far the number of clinging jellyfish found at the Shore, from the Shrewsbury River to the Forked River, has been low. A map maintained by the state DEP shows where clinging jellyfish have been confirmed and sites that have been investigated but no clinging jellyfish were found (click here).

The clinging jellyfish, a native of the Pacific Ocean, is small and very difficult to spot in the water. They range from the size of a dime to about the size of a quarter and have a distinctive red, orange or violet cross across their middle.

Both the adult, or medusa, and polyp stages of the clinging jellyfish are capable of stinging, a mechanism the species uses to stun prey and to defend against predators. Each jellyfish can trail 60 to 90 tentacles that uncoil like sharp threads and emit painful neurotoxins. Tentacles grow to be about 3 inches long, and they primarily feed on zooplankton.

They are not known to inhabit ocean beaches or other sandy areas but tend to attach to submerged aquatic vegetation and algae in back bays and estuaries. Anyone wading through these areas, especially near aquatic vegetation, should take precautions, such as wearing boots or waders to protect themselves. Swimming at lifeguarded beaches is always encouraged.

A sting can produce severe pain and other localized symptoms and can result in hospitalization in some individuals. There is no method to effectively control clinging jellyfish populations in the aquatic environment.

Sea nettles, another type of jellyfish with a less powerful sting, are common in Barnegat Bay but are much larger. They prey on clinging jellyfish.

This story contains reporting from Patch's Karen Wall.