MONMOUTH BEACH, New Jersey (WABC) -- State officials have issued a warning to New Jersey residents this holiday weekend about clinging jellyfish.
The jellyfish are back in the Shrewsbury River in Monmouth County. They are tiny, about the size of a dime, but they pack a powerful sting.
The jellyfish were first confirmed in the river back in 2016.
This week researchers found about 40 of them in an area off Monmouth Beach known as The Hook.
Experts say the clinging jellyfish is not known to inhabit ocean beaches or other sandy areas but tends to attach itself to submerged aquatic vegetation and algae in back bays and estuaries, areas not heavily used for swimming.
The clinging jellyfish, a native to the Pacific Ocean, is very difficult to spot in the water. A sting can produce severe pain and other localized symptoms and, in some cases, result in hospitalization. It is not known how the species found its way into the Shrewsbury River.
Anyone wading through these areas, especially near aquatic vegetation, should take precautions, such as wearing waders or boots to protect themselves. Swimming near lifeguarded beaches is, as always, encouraged.
If stung by a clinging jellyfish:
Apply white vinegar to the affected area to immobilize any remaining stinging cells.
Rinse the area with salt water and remove any remaining tentacle materials using gloves or a thick towel.
A hot compress or cold pack can then be applied to alleviate pain.
If symptoms persist or pain increases instead of subsiding, seek prompt medical attention.
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Warning issued about clinging jellyfish in river near Jersey Shore