People who frequent a New Jersey river known for its fishing and kayaking are advised to watch out for a rare type of 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.

(AP)