'Highly Venomous' Portuguese Man-of-Wars Are Washing Ashore on South Carolina Beaches, Authorities Warn

The Portuguese man-of-war (Physalia physalis) is a jellyfish-like marine creature which possesses a powerful sting that can cause excruciating pain in humans.

There have been a number of recent sightings of the animals washed ashore on several beaches in South Carolina. And now, local authorities are warning beachgoers to beware.

On June 7, the South Carolina Department of Natural Resources (DNR)—a state agency responsible for regulating outdoor activities such as hunting and fishing, as well as regional conservation initiatives—released a statement urging people to stay away if they spotted a man-of-war.

"You should steer clear of these highly venomous relatives of jellyfish both in the water and ashore, as even a dead man-of-war has a sting strong enough to sometimes require medical attention," the DNR statement read. "Fortunately, the bright blue 'float' of a man-of-war makes them easy to recognize and avoid."

"They have recently washed onto beaches from Florida to North Carolina," the statement continued.

The balloon-like float—which can also be violet or pink in color—often rises several inches above the waterline while the the animal is floating in the sea, according to the National Oceanic and Atmospheric Administration.

With no means of propulsion, the Portuguese man-of-war relies on the wind and ocean currents to move itself. In fact, the float acts as a kind of sail to harness wind power, hence the creature's name—a reference to a type of 18th-century warship.

The man-of-war is unusual in the sense that it is not technically a single organism. While often mistaken for a jellyfish, it actually belongs to a group of closely related animals known as siphonophores.

Each siphonophore comprises a colony of genetically identical individuals known as "zooids" which each perform specific function. For example, the man-of-war contains different zooids that are responsible for floating, catching prey, feeding and reproduction.

The man-of-war has several long tentacles hanging below the float—which typically measure about 30 feet in length—that it uses to deliver venom to prey, usually small fish and crustaceans.

If a human comes into contact with the tentacles, they will likely experience severe pain lasting between one and three hours and may be left with whip-like injuries on the skin. Some stings may require medical attention and, in extreme cases, the venom can even lead to death in humans, although this is rare.

Care must be taken when encountering a man-of-war that has been washed ashore because the tentacles are still capable of stinging for some time after the animal has died or the body part has become detached.

Portuguese man-of-war
A Portuguese man-of-war. SCDNR/SERTC