What's that blob on beach?

The large mystery jellyfish found on the beach at Isle of Palms is likely either a lion's mane or sea nettle.

ISLE OF PALMS - It's been a weird year for jellyfish - a tropical box jelly showed up in New Jersey a few months back. So when a big ugly blob washed up on its back at the Wild Dunes beach last week, it could well have been an "upside-down" jelly, a type rarely seen here.

That's what Rod Stadum suspected, after he combed a coastal fauna guide to identify it. S.C. Department of Natural Resources biologists didn't think so when a photograph was forwarded to them.

Maybe it's a moon jelly, DNR biologist Mollie McDonough Reynolds ventured. But neither she nor others could be sure.

The problem is, there aren't a lot of people who study jellyfish exhaustively enough to be considered expert.

And the jelly is one amorphous critter, all right. It can get tough to ferret out a type among more than 350 types of jellies worldwide.

They're nothing if not prolific. Some scientists are alarmed that jellyfish swarms sometimes covering hundreds of miles have begun taking over the ocean in regions of the world - starving out food fish, injuring swimmers, overloading nets and capsizing fishing boats, and clogging the pipes to power plants and nuclear vessels.

The concern is that warmer waters, overfishing and pollution are depleting other species while giving jellyfish the habitat they need to thrive.

Upside-down jellies are cool creatures, for sure. They float on their backs along the seafloor with a flurry of tentacles extending up, feeding on algae. But they are strictly Caribbean creatures, and aren't considered to wander far.

They haven't been found in the South Atlantic Bight waters that include South Carolina's coast.

And they rarely if ever get as big as the one Stadum wandered across, three times as big as his boot.

The retired physicist and computer engineer has been coming to and spending winter months at Isle of Palms for a decade or more and regularly walks the beach. He had never come across anything like that.

"It was clearly round and flexible, and the rim was flapping around," he said. "I've never seen a jellyfish with a body that was attached to plankton or whatever the brownish material was."

Luckily for Stadum, the Southeast coast does have at least one resident jellyfish guru - biologist William Gillan, of Boynton Beach, Fla. Among his other credits, he discovered a type, the Bonaire banded box jellyfish.

Stadum's jelly is a variety of Chrysaora, Gillan said after looking at the emailed photo. It's likely a lion's mane, which can have a wide variety of colors, hues, and shading patterns and is common along the East Coast, he said. Then he added, or it could be a (very similar) sea nettle.

That should settle it.