"I saw a man-of-war! I'm getting out of here!" yelled the swimmer, who'd gotten in only up to his ankles. Others stopped at water's edge, where gelatinous clumps of jellyfish were washing onto the sands of the Outer Banks. In the shallows drifted the still-whole versions of the things. The only people to brave the threat strings were those on rafts.

"Stinging nettles," drawled a woman from Richmond. "They're all over Virginia Beach, but this is the first time I've seen them here" in North Carolina.

Actually there were neither the venomous Portuguese man-of-war -- which sometimes floats in from the Gulf Stream on a southeasterly wind -- nor the "stinging nettle," a kind of weed, but Chrysaora (Dactylometra) quinquecirrha, the very common sea nettles, come on the tides to visit from Pamlico Sound.

Jellyfish can be a curiosity or the bane of a vacation. You can't wait them out; they keep swimming around long after it's too cold for people. David G. Cargo, a research associate at the Chesapeake Biological Laboratory, estimates that we can see some 25 species in this area -- when one floats off, there's always another.

"Even though the jellyfish situation has abated slightly in the Nags Head area, we do have the cabbage-head or jellybomb" in the inlets of Pamlico Sound, said Frank J. Schwartz, at the University of North Carolina's Institute of Marine Sciences in nearby Morehead City. The cabbage-head, he said, is "as big as a bowling ball, no tentacles, and has a little brown skirt."

High temperature and high salinity bring them, said Schwartz, a professor of zoology and marine sciences. High salinity is a result of drought last year and this. "The jellybomb is a pain in the neck in such abundance," he said. "We have had waterways so clogged you couldn't get a boat through. They're not fishing much this time of year, but when they do fish their nets just come up solid jam-packed with jellybombs."

But these don't sting, and you can always swim around them. "You can have a lot of fun tossing them back and forth as beachballs," suggested Schwartz.

Other jellyfish are not so much fun: jellyfish with stinging cells that, triggered physically or chemically, fire a coiled thread that carries a toxin. The most common reaction to being stung is a rash and itching or burning, but sometimes a severe attack will cause difficulty in breathing, which can kill someone whose resistance is low. "We don't have any suggestion that any deaths have resulted from the sea nettle," Cargo said reassuringly. "But some species are lethal, especially in the Australian area."

If you are stung by sea nettles, "meat tenderizer is good," said Cargo. "Or a first-aid cream or spray with an anesthetic; maybe alcohol or baking soda. If it works and somebody feels better for it, I think that is what they ought to try. Some of it is psychosomatic." If nothing else is available, flush the affected area with water.

"Everyone uses something different," said Schwartz. "Talk to the fisherman, he uses crankcase oil, pickle juice. A lot of people just rub sand into it -- of course, that's the worst thing to do. That just aggravates it. If you could get straight papaya juice, then you could do away with meat tenderizer." In any case, in four or five hours it will be all over.

Though Cargo had thought it would be a banner year for jellyfish in the Chesapeake Bay because of high salinity in April, so far it's only been "an average year." At the Chesapeake Biological Laboratory at Solomons, people count them alongside a 700-foot pier that juts out into the bay. "Instead of an average of 300 jellyfish" at any one time, as they'd expected, "it's an average of 100," he said.

Jellyfish, with the pulsing bell shape and hanging tentacles that characterize the medusa or swimming stage, are at the mercy of the wind. They're swept in to shore; an offshore wind may sweep them out again. When waves are wafting things along in a gentle fashion, the shorelines are full of jellyfish, said Cargo. They eat most anything they can capture and stun with their stinging cells: a lot of plankton, crustaceans, small marine worms, the occasional small fish, and the sea walnut, a fellow invertebrate. Do jellyfish have an economic value? "Not so far as we know," said Cargo, "except that some species are eaten in the Orient."

Jellyfish are people-resistant. The "polyp" stage of the sea nettle winters over on the bottom of the Bay, "attached to the undersides of almost anything -- rocks, bottles, cans, logs -- you name it," said Cargo. They reproduce asexually by budding in this stage and heterosexually by laying and fertilizing eggs in the mature medusa stage.

"We don't think we are ever going to be able to control them or reduce their numbers. They have so many resistant stages," said Cargo. "Their overwintering stages are where oysters are prevalent. "We can't start throwing things around in those areas, you see." And even if they found something that would erase only jellyfish, the Bay is just too big.

The laboratory studied the control of jellyfish for about eight years: "The more we looked, the less we thought we were going to be able to do that. So we want to make visitors to the Tidewater area better able to live with it," said Cargo.

The lab monitors life stages to predict how many jellyfish there'll be and where, looking for more esthetically acceptable and efficient swimming-beach barriers; and it's had some promising results with water jets, as opposed to the nettle nets that have been strung out in swimming areas at beaches along the Bay. The nettle nets, said Cargo, need continued maintenance, are expensive to install and not foolproof, since nettles that are swept into them with any force break up and parts of them go through and sting anyway. The lab is also trying to work up some anti-venom or anti-toxic principle that will either protect in advance or relieve the pain afterward.

After a few days of being plagued with jellyfish at Nags Head, and realizing that they were not going to rise out of the sea and attack, young girls dared to scoop them up in buckets and plastic strainers and dump them, tentacles dragging, on the sand. Some swimmers felt a little safer for that, and went in for a dip near where the girls were jellyfishing. But this may have been less than helpful: According to Schwartz, in Egyptian tombs there have been discovered dead and dried-up jellyfish that still pack a punch. "The stinging cells are very resistant to desiccation," he said. "People think they are being helpful by throwing the jellyfish on the pier and letting them dry in the sun -- then they step on them and are surprised at the sting."