A 20-year-old man stung by what was believed to be a clinging jellyfish says that it was some of the worst pain he has ever experienced.

Matt Carlo, of Lincroft, was swimming in the Shrewsbury River after dark in Oceanport when he was stung on his side.

"It just felt a little tingly and weird at first then a half-hour after that, it hit my muscles and my whole body from like from my toes to my fingertips. Everything just kind of hurt," Carlo says.

Carlo says that he went to the doctor after he was stung, but he was sent home because doctors thought it was a regular jellyfish sting. When his symptoms became worse, he went to the hospital.

"There wasn't much they could do for me, all they could do was treat my symptoms, and since all it was was pain, they could just give me pain medication," he says. "I was just on morphine for about 24 hours."

Scientists with the New Jersey Department of Environmental Protection and Montclair State University searched the Shrewsbury River, Barnegat Bay and Manasquan River for more jellyfish. Several more were found.

Clinging jellyfish are a dangerous species of jellyfish that are usually found in the Pacific Ocean. They were recently discovered along the Jersey Shore.

"We're trying to get a handle on what the actual numbers are," says the DEP's Dr. Gary Buchanan. "We want to get a sense if there are just isolated areas that have them."

The jellyfish gets its name because it is usually found clinging to eelgrass or seaweed. Clinging jellyfish prefer calm waters, rather than the rougher surf in the ocean. They typically stay near the bottom of the water during sunlight and emerge to feed at night and on overcast days.

Being stung by a clinging jellyfish can lead to a variety of symptoms and, in severe cases, lead to kidney failure.