Public safety officials are warning beach-goers after several Portuguese man-of-war sightings on Sullivan's Island.
No stings had been reported as of Wednesday, but officials are urging everyone to be cautious on the beach and in the water, the town said in a statement.
The Portuguese man-of-war is a predatory marine jellyfish-type creature found in the Atlantic, Pacific and Indian oceans. Its long tentacles can dispense painful stings to swimmers, leaving red welts and lasting inflammation.
In extreme cases the venom can travel to the lymph nodes and mimic a dangerous allergic reaction.
An allergic reaction from a Portuguese man-of-war sting is rare, said Dr. Keith Borg, associate professor of emergency medicine at the Medical University of South Carolina. A key difference between the animals and other jellyfish-type organisms is the length of the tentacles, which can break off and still cause harm to unsuspecting humans.
"Portuguese man-of-war tentacles are much, much worse," Borg said.
Though he has not seen any patients so far this season with stings from the jellyfish relative, Borg said Portuguese man-of-war stings he's seen in the past have been more severe than those from most true jellyfish.
"The treatment initially is straightforward," Borg said, adding that stings should be treated with a mixture of water and sand to scrape off any remaining barbs.
The man-of-war can be found washed up on beaches or floating on the water's surface.
The same migratory phenomenon was seen along the South Carolina coast this time last year. The animals are sometimes found in groups of 1,000 or more, and most commonly move by drifting on currents by the power of the wind.
The bulbs of the animals can run as big as a basketball, while their painful tentacles can stretch for dozens of feet below the water.