Portuguese Man-of-War The Portuguese man o’ war (Scientific name: Physalia physalis) is often called a jellyfish, but is actually a species of siphonophore, a group of animals that are closely related to jellyfish. A siphonophore is unusual in that it is comprised of a colony of specialized, genetically identical individuals called zooids — clones — with various forms and functions, all working together as one. Found mostly in tropical and subtropical seas, men o' war are propelled by winds and ocean currents alone, and sometimes float in legions of 1,000 or more! [Source: NOAA]
The Portuguese Man-of-War is the sole member of the Siphonophora with a unisexual colony. Distinguished by a contractile, horizontal float, it is comprised of chains of polyps that hang from a gas-filled float. Each of the four specialized chains of a man o’ war has a specialized function: one tends to reproduction; another specializes in stinging and capturing prey; another absorbs nutrients from the prey; and another is involved in floating, . The chains form tentacles, which can extend for more than 20 meters. The Portuguese man-of-war packs a very potent and toxic poison. Humans that are stung usually feel excruciating pain but do not die.
Portuguese man-of-war are been found in the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Caribbean, and the Sargasso Sea. They float on or near the surface of the water and can be found in coastal areas and the open sea. They are often seen along the Florida Keys and the Atlantic coast, in the Gulf Stream, the Gulf of Mexico, the Indian Ocean, the Caribbean Sea, and other warm areas of the Atlantic and Pacific oceans. They are especially common in the warm waters of the Sargasso Sea. /=\
Man-of-wars were 18th-century armed sailing ship. The sea creatures gets its name from their resemblance to the Portuguese versions of these ships at full sail. The sea creature’s sail is a gelatinous “candle” between 15 and 30 centimeters wide that allows the animal to be pushed by winds at the surface of the ocean.
Portuguese man-of-war are reasonably common. Known as bluebottles in Australia, they are not considered endangered or threatened. They have not been evaluated for the International Union for Conservation of Nature (IUCN) Red List. They have no special status according to the Convention on the International Trade in Endangered Species (CITES).
Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures
Portuguese Man-of-War Physical Characteristics
Portuguese man-of-war are venomous, ectothermic (use heat from the environment and adapt their behavior to regulate body temperature), heterothermic (have a body temperature that fluctuates with the surrounding environment) and have radial symmetry (symmetry around a central axis). [Source: Mindy B. Kurlansky, Animal Diversity Web (ADW) /=]
Resembling an 18th-century Portuguese warship under full sail, the man o’ war is recognized by its balloon-like float, which may be blue, violet, or pink and rises up to six inches above the waterline. Lurking below the float are long strands of tentacles and polyps that grow to an average of 10 meters (about 33 feet) and may extend by as much as 30 meters (about 100 feet). The tentacles contain stinging nematocysts, microscopic capsules loaded with coiled, barbed tubes that deliver venom capable of paralyzing and killing small fish and crustaceans.While the man o’ war’s sting is rarely deadly to people, it packs a painful punch and causes welts on exposed skin. [Source: NOAA]
According to Animal Diversity Web: The Portuguese man-of-war is a floating hydrozoan. It is actually a colony consisting of four types of polyps: a pneumatophore, or float; dactylozooids, or tentacles; gastrozooids, or feeding zooids; and gonozooids which produce eggs and sperm for reproduction.Cnidocytes (stinging cells) are located in the tentacles. Sensory cells are numerous and are located in the epidermis of the tentacles and the region around the mouths. Generally, the sensory cells are receptors for touch and temperature. /=\
Portuguese Man-of-War Locomotion, Feeding and Predators
The Portuguese man-of-war cannot swim. They float and are pushed by winds with the aid of its pneumatophore, or float Locomotion is generally passive, driven by wind and current.. The float is a long, gas-filled bladder, formed as an overgrown polyp in the shape of a closed bag. Some Men-of-War are "left-sided," while others are "right-sided." The "left-sided" individual drifts at an angle of 45 degrees to the right of the direction from which the wind is blowing, and the "right-sided" individual does the opposite. This distinction is crucial in the spreading of the animals more evenly over the warm oceans of the world. [Source: Mindy B. Kurlansky, Animal Diversity Web (ADW) /=]
Portuguese man-of-war feed mainly on fish fry (young fish) and small adult fish, and it also consumes shrimp, other crustaceans, and other small animals in the plankton. Nearly 70 to 90 percent of the prey are fish. The Portuguese man-of-war is eaten by some fish and crustaceans (such as the sand crab) that can be of commercial value. /=\
Portuguese man-of-war trap food in their tentacles. According to Animal Diversity Web: The tentacles, or dactylozooids, are the Man-of-War's main mechanisms for catching its prey and are also used for defense. Portuguese man-of-war sometimes traps and consumes larger fishes such as flying fish and mackerel, though fishes as large as these generally manage to escape from the tentacles. The food of the Man-of-War is digested in its bag-like stomachs (gastrozooids), which are located along the underside of the float. The gastrozooids digest the prey by secreting enzymes that break down proteins, carbohydrates and fats. Each Man-of-War has multiple gastrozooids complete with individual mouths. After the food has been digested, any undigestible remains are pushed out through the mouths. The nourishment from the digested food is absorbed into the body and eventually circulates to the different polyps in the colony.
The man-of-war fish is a small fish that hangs around Portuguese man-of-wars when it is a juvenile for protection and scraps of food in the same way that clownfish hang out at sea anemones. Strangely enough though it has only limited immunity to the jellyfish’s sting and instead relies in its swimming dexterity to avoid being stung, It also occasionally feeds on jellyfish tentacles which makes it more of parasite than a benign creature involved in a symbiotic relationship.. When the fish becomes an adult it leaves the Portuguese man-of-war and heads for deeper waters.
Portuguese Man-of-War Reproduction
Portuguese man-of-war are oviparous (young are hatched from eggs) and iteroparous (offspring are produced in groups). They engage in seasonal breeding and employ sexual fertilization in which sperm from the male parent fertilizes an egg from the female parent. Reproduction is external, meaning the male’s sperm fertilizes the female’s egg outside her body.There is no parental involvement in the raising of offspring.[Source: Mindy B. Kurlansky, Animal Diversity Web (ADW) /=]
Portuguese man-of-war are dioecious (they are divided into male and female individuals). An "individual" is actually a colony of unisexual organisms. Every individual has specific gonozooids (sex organs or reproductive parts of the animals, either male or female). Each gonozooid is comprised of gonophores, which are little more than sacs containing either ovaries or testes. /=\
Fertilization of Portuguese man-of-war is assumed to occur in the open water, because eggs and sperm from the gonozooids are shed into the water. This may happen as gonozooids themselves are broken off and released from the colony. The release of gonozooids may be a chemical response occurring when groups of individuals are present in one locality. Critical density is probably required for successful fertilization. Fertilization may take place close to the surface. Most reproduction takes place in the fall, producing the great abundance of young seen during the winter and spring. It is not known what triggers this spawning cycle but it probably begins in the Atlantic Ocean. /=\
Portuguese Man-of-War Development
One person posted on Quora.com: Siphonophores like the Man o' War are confusing animals but often the "colonial" concept does more to confuse people than clarify how they work. It is easier to think of them as one big animal (or usually looooong animal — up to 30 meters) with different parts serving different functions — not so different from a more typical animal where different organs do different things. The zooids are all connected to each other and genetically identical, sharing nutrition and nervous impulses, so no need to transfer DNA, etc. They start out as little buds and then grow and differentiate.
Larvae probably develop very rapidly to small floating forms. According to Animal Diversity Web: Each gonophore has a central spadix of multinucleate endodermal cells separating the coelenteron from a layer of germ cells. Covering each germ cell is a layer of ectodermal tissue. When gonophores first bud, the germ layer is a cap of cells on top of the endodermal spadix. As gonophores mature, the germ cells develop into a layer covering the spadix. [Source: Mindy B. Kurlansky, Animal Diversity Web (ADW) /=]
Spermatogonia form a thick layer, while oogonia form a convoluted band several cells wide, but only one cell layer thick. There is very little cytoplasmic material within these cells, except during rare instances when cell division is occurring. Oogonia begin development at approximately the same size as spermatogonia, but become considerably larger. All oogonia are apparently formed at an early stage of gonophore development prior to the occurrence of enlargement. Interestingly, there appears to be yolk globules within the cytoplasm of most oogonia.
Portuguese Man-of-War Stings
Portuguese man o’ war’s stings are rarely deadly to people, but they are painful and cause welts on exposed skin. Man-of-war tentacles have coiled stingers. Cnidocytes (stinging cells) are located in the stingers. Toxin are forced out of the man o’war by osmotic and hydrostatic pressure. Cnidocytes are the characteristic predator-deterring and food-obtaining mechanisms of jellyfish and their close relatives. Portuguese man-of-war have two sizes of cnidocytes, small ones and large ones. Beachcombers be warned: These cells retain their potency long after an individual has died. The stalwart man o’ war may still sting you even weeks after having washed ashore. [Source: Mindy B. Kurlansky, Animal Diversity Web (ADW) /=]
Some sources say there have been no recorded deaths due to Portuguese man o’war’s stings albiet they can be extremely painful. Experts speculate that some people may have been stung and then drowned as they suffered an allergic reaction. These may account for deaths attributed to the jellyfish-like creature.
When stung by a Portuguese man o' war, what exactly is happening with each individual sting? Christopher Corn, a teacher posted on Quora.com in 2015: Each tentacle has around a gazillion stinging cells called nematocysts. Each cell has a little harpoon nestled in it. When you brush up against the tentacle, they fire (just like a harpoon), pierce your skin and and inject venom.
Man-of-war venom — a neurotoxin — is meant to paralyze small fish until they can be eaten. In humans, reactions can be mild to moderate. In rare cases, they can be life-threatening. The inflammatory response resulting from stings is due to the release of histamines from mast cells within human victims. According to Mount Nittany Health: After a sting, the tentacles leave long, stringy red welts on the skin. The welts last from minutes to hours. There is local pain, burning, swelling, and redness. This rash may come and go for up to 6 weeks. Cramps, fever, sweating, weakness, faintness, dizziness, nausea, vomiting, and diarrhea may also occur in stronger reactions. Over-the-counter medicines are used to treat generalized symptoms of pain, itching, and swelling. Severe reactions require hospital treatment. [Source:Mount Nittany Health]
What's Its Like to be Stung by a Portuguese Man O' War?
Sophia Marcinik posted on Quora.com in 2020: I was literally just stung about three hours ago in Maui. I am an 18 year old girl. I was swimming and the tentacles wrapped around all four of my limbs. Imagine being shocked with electricity nonstop all over your body. Then it turns into bee stings. And the pain is paralyzing. It’s horrible. It hurts right now but I’m ok. Do NOT do the following; wash with fresh water, use vinegar, or touch it. I lost consciousness for about a minute and then paramedics came. I was told to take a warm bath but I have yet to do that. [Source: Quora.com
John Carlton, a Naval Architect, posted; Once, long ago, while sailing a little racing dinghy by myself, from Sydney Harbour a wave full of Blue Bottles (Portuguese Men of War in Australian) broke over the boat. The water drained out through the centreboard case, but the Blue Bottles stayed. Sailing the boat from trapeze kept me out of them, but every time I tacked, which in the Nor’Easter was maybe five times, I had to wade through them. It hurt like hell, and I was bit of a mess, and feeling very sorry for myself, by the time I got off the boat. But, after a few days, it was a good story, and that is about all.
Christopher Corn, a teacher, posted in 2015: Feels like a burn. I was surfing off of Bondi in Sydney and had a Portuguese man of war tentacle get wrapped around my arm. I didn't see the sail (the air bag floats on top of the water that is above the main body of the jellyfish) so it was likely just a piece that had been ripped of by the surf. It looked like a round cooked rice noodle with little blue beads suspended in it. I peeled it off with my fingers. The nematocysts that actually sting you are not powerful enough to fire through the thicker skin on your hands. I've heard that if you are really tangled up, Ammonia can be used to cause the unfired nematocysts to fire so it doesn't make it worse when you try and remove them. It felt like a ring of fire with a narrow red welt where it was wrapped around my arm. The burning sensation lasted for about 20 minutes and after that it just itched for a day. No scarring or other lasting injury.
Brian Collins, a student at the University of Queensland, posted in 2017: It hurts and the pain lasts all day. Unlike the other answer, I got stung by a small live one. I originally went over what happened here (you can read that for the background info): Submerging it in warm water helps. At some points the pain went away completely when I had my hand submerged in warm water, but then it would come back. The biggest difference for me between that, and the ones in the Puget Sound where I am from, are that Portuguese Man O’ War venom sticks. You have this blue crap all over you, and then when you wipe it off, it burns your other body parts. You have to be careful not to touch it, while wiping the venom off of you. The scariest part for me was when the pain spread to my shoulder. I panicked a little in the hospital waiting room and tied a belt around my arm at one point. It left marks on three of my fingers which are still here 5 days later:
Mike Stobaugh, posted in 2021: I spent many hours during my youthful years surfing in Hawaii. Honestly I’ve lost count how many times I’ve been stung by a Portuguese Man-of-War. Many times these occurred far from shore. The best treatment for us was to scrub the sting with common sand. A buddy would dive to the ocean bottom and bring up a handful of sand and put on my surfboard. The scrubbing would be slightly irritating but far less painful than the sting itself. Sometimes I’d repeat this a few times, always getting enough relief to stay out and catch more waves. They were very common. Rarely one would splash atop our surfboard and find its way into our swim trunks. I’d laugh when it happened to one of my buddies, cry if it happened to me (same remedy).
Bad Sting from a Portugese Man O' War
Describing what happened after he leapt into water unknowingly filled with Portuguese jellyfish at night, Brooke Morton wrote in Scuba Diving: The pain is instant. The night sky is as inky as the water surrounding me, but I don’t need to see to know what just happened...The heat of the sting starts radiating up my arms and legs...There is no wind....Caribbean winters are famous for consistent trade winds, which typically blow these deadly beasties far offshore — but not this week....In every direction, purple yarn tentacles knot with my movements, creating a nest. I’m scared to lift my arms to swim to the ladder, but it’s the only option. [Source: Brooke Morton, Scuba Diving November 19, 2016
“This grimace-inducing burning isn’t centralized like a bee sting, but spread out, as if dozens of hands are extinguishing cigarettes on my skin. But I can’t recoil. When I retract, water swirls the tentacles right back on top of me. Finally, I grasp the ladder. I want to be deliriously happy, but I’m racing a clock. Stinging marine injuries need to be handled swiftly....I rack my brain to recall the remedy. Scrape a credit card across the affected area to remove the sticky stinging cells. I’ve no wallet on me, so I run to the beach for the next best thing — sand. I pull up handfuls to slough my arms from the nematocysts. Again and again, but I don’t think it’s working. I don’t feel good yet.
Then comes the bad idea. Wanting to wash off this nightmare, I drive home to shower. Too bad that in my fog of adrenaline, I forget that freshwater is the worst action for marine injuries. The introduction of a foreign environment triggers the cells to release toxins. For a few brief moments, I feel better. Then breathing becomes difficult. It’s as if I’ve swallowed an entire shaker of pepper. Drinking water does nothing, and I know I’m in over my head.. I dial 9-1-1. Sleep tempts, but I can’t nod off. An hour passes. I call 9-1-1 again to find that the ambulance arrived — but at the wrong address. Just as I’m about to pass out, bundled in a wool blanket to warm my chill, the paramedics knock. Under the ER’s glaring lights, I’m given three shots: Epinephrine. Steroids. Antihistamines.
The drugs settle in. I learn I suffered anaphylactic shock. Oops. I sleep soundly through the night, waking to find that my injuries have rendered my bum too sore to sit. It’s painful, sure, but nothing compared to the suffering that comes when I learn that the rumors of my stupidity traveled quickly, unlike last night’s ambulance.
Treatment for Portuguese Man-of-War Stings
What is the best way to treat a Portuguese Man O War sting? Thierry Meier who lives in Zurich posted on Quora.com in 2013: Don't scratch if you got stung, if you do so, the tentacles will release even more of their powerful toxin in to your bloodstream. A lot of people say Vinegar is the weapon of choice. This is certainly true when it comes to box jellyfish, for blue bottle jellyfish respectively Portuguese Man O War, this is not true. Ice helps because it controls the spread of the poison and numbs the area you got stung. However, it does not deactivate the toxin which got injected in to your bloodstream. Believe it or not, hot water is the best thing you can do. If you got stung in your hand, put your hand in to a
According to Mount Nittany Health: These tips can help you prevent and care for a sting: 1) Before swimming in oceans or bays, check local beach reports for warnings of Portuguese man-of-wars. Don't swim in the water when they are present. 2) If you find one washed up on the beach, don' touch it. Even dead man-of-wars or detached tentacles can sting. 3) If you are stung, rinse the area with saltwater. Apply concentrated vinegar solution if available. This will inactivate the stingers and prevent the release of more toxin. Then with a gloved hand try to remove the tentacles. 4) Put the affected area in hot saltwater for about 20 minutes. 5) Get medical care for moderate to severe reactions. [Source: Mount Nittany Health
The following guidelines will help you care for yourself at home: 1) Well after the sting was treated and all tentacles were removed, put an ice pack over the injured area for 20 minutes. Do this every 2 hours for the first day. Do this 3 to 4 times a day for the next few days until the pain and swelling improve. To make an ice pack, put ice cubes in a plastic bag that seals at the top. Wrap the bag in a clean, thin towel or cloth. Never put ice or an ice pack directly on the skin. Over-the-counter creams with hydrocortisone and benzocaine may reduce the itching and local pain. Oral antihistamines containing diphenhydramine can be found at pharmacies and grocery stores. Unless a prescription antihistamine was given, you may use these to reduce itching if large areas of the skin are affected. You may use ibuprofen for pain and swelling, unless another pain medicine was prescribed.
Image Sources: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated May 2023