Walking on a beach or swimming in the ocean are generally harmless activities, but encounters with sea creatures can leave you feeling stung, burned, or itchy. Read on to learn what to do if you have a jellyfish or Portuguese man-of-war sting, seabather's eruption, or a coral scrape.
Jellyfish and Portuguese man-of-wars are members of a large group of venomous marine animals that also includes fire coral and sea anemones. They are present all over the world and cause injury and illness through the release of venom when their tentacles come in contact with skin (stinging). Tentacles are long, slender, flexible growths found on jellyfish, Portuguese man-of-wars, squid, and octopuses. Tentacles are used for grasping, feeling, moving, and killing prey by stinging. While the sting of a jellyfish or Portuguese man-of-war can cause severe illness and extreme pain, documented deaths are rare.
Jellyfish are often present in coastal waters, having been brought ashore by winds or ocean currents. They are most common in warm ocean waters, especially along the Atlantic coast of the United States. Stings result from contact with the tentacles, which trail from the jellyfish's see-through body. Jellyfish swimming in the water are often hard to see. Beached jellyfish, which may look like the cellophane wrapper from a cigarette pack, can sting if touched.
Jellyfish stings cause immediate, intense pain and burning that can last for several hours. Raised, red welts develop along the site of the sting, which may look like you have been hit with a whip. The welts may last for 1 to 2 weeks, and itchy skin rashes may appear 1 to 4 weeks after the sting. Fortunately, most jellyfish stings are not severe. Extensive stings, allergic reactions, or severe reactions are not common but do occur. To avoid the risk of drowning, swimmers should get out of the water as soon as they realize they have been stung.
The box jellyfish, which is found in the Indian Ocean and South Pacific, can cause a fatal reaction. It is the only jellyfish for which a specific antidote (antivenin) exists. If you get this antivenin, it may save your life.
Seabather's eruption is a rash that develops from the stings of jellyfish or sea anemone larvae. The rash can be quite itchy and annoying, but it usually goes away without medical treatment in 10 to 14 days.
Portuguese man-of-wars (hydrozoans) live in warm seas throughout the world but are most common in the tropical and subtropical regions of the Pacific and Indian oceans and in the Gulf Stream of the North Atlantic Ocean. They float on the surface of the water with their long, stinging tentacles trailing in the water below. Detached tentacles that wash up on the beach can remain dangerous for months.