TOMS RIVER, N.J. (CBSNewYork/AP) — Folks who frequent a New Jersey river known for its fishing and kayaking are advised to watch out for a rare type of tiny jellyfish with a powerful and painful sting.

The Department of Environmental Protection is advising recreational users of the Metedeconk River in Ocean County to be on the lookout for clinging jellyfish. Clinging jellyfish are native to the Pacific Ocean. They were previously spotted in Monmouth County’s Shrewsbury River last month.

The jellyfish about the size of a dime and difficult to spot in the water. Their stings can produce severe pain and may result in hospitalization. They tend to attach to submerged plants and algae in areas not usually used for swimming, but officials urge caution.

The DEP is urging the public to be careful in areas where the jellyfish are suspected. Anyone wading through these areas, especially near aquatic vegetation, should take precautions, such as wearing boots or waders to protect themselves. Swimming near lifeguarded beaches is recommended.

The clinging jellyfish was first confirmed in New Jersey in 2016 in the Manasquan River at the Point Pleasant Canal. The DEP has been working with Montclair State University in studying the possible distribution of clinging jellyfish in New Jersey.

Montclair researchers this week confirmed the presence of about 15 clinging jellyfish of varying sizes off a private dock in the Metedeconk. Genetic testing is being conducted for final verification.

“We don’t know how long they’ve been here. They might have been here for decades and nobody’s actually seen them,” said Dr. Paul Bologna, director of marine biology at Montclair State. “They’re very, very small – size of a dime, size of a quarter is about as big as they get – but they’ll put you in the hospital.”

The Prendeville siblings were playing in the water behind their grandmother’s house when they found the jellyfish on seaweed. Fortunately, they had on protective gear.

“We’re the only ones that found it in the Metedeconk River,” said 10-year-old Nick. “It’s really frightening and cool at the same time.”

“I’ve never seen this type of species before and we’ve been here for a long time,” their grandmother Trudy Bonavita said.

If stung by a clinging jellyfish:

  1. Apply white vinegar to the affected area to immobilize any remaining stinging cells.
  2. Rinse the area with salt water and remove any remaining tentacle materials using gloves or a thick towel.
  3. A hot compress or cold pack can then be applied to alleviate pain.
  4. If symptoms persist or pain increases instead of subsiding, seek prompt medical attention.

Experts warn, if you see a clinging jellyfish, do not try to capture it.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

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