(FOX 5 NEWS) - New Jersey authorities are warning people about a small jellyfish that packs a big and potentially dangerous punch.
A clinging jellyfish stung a man who was swimming in the Shrewsbury River in Monmouth Beach last weekend. He was hospitalized.
The Monmouth Beach OEM said this week that locals found what may be three more clinging jellyfish in the Shrewsbury River.
Clinging jellyfish are only about an inch in diameter but their sting can cause serious medical problems, according to authorities.
Although clinging jellyfish are native to the Pacific Ocean, they have been found along the Eastern seaboard for more than a century, according to the New Jersey Department of Environmental Protection.
"They are found in shallow bay waters and cling to vegetation, such as eel grass, during the day," the department said in a fact sheet. "They do not produce large populations as some other jellyfish, but can be found in local areas in small to moderate numbers. ... Additionally, clinging jellyfish are not likely to be abundant in areas heavily used by swimmers, but could affect casual waders and people gathering shellfish near eelgrass beds."