The Portuguese Man-of-War is the sole member of the Siphonophora with a unisexual colony; it is distinguished by a contractile, horizontal float. Although Siphonophora are generally considered to be the most specialized hydrozoans, some researchers claim that it is in fact the most primitive order, with the medusa and the polyp not fully differentiated. Additional support for this view comes from the observation that the regenerative powers of the man-of-war are poor, in contrast to most other jellyfish.
Physalia physalis is not especially rare, and not considered to need special conservation effort at this time.
US Federal List: no special status
CITES: no special status
This species can hurt tourists and tourism in areas where it is common, due to stings (of neurotoxins) from its cnidocytes. Much money is spent each year to treat swimmers who have been stung by the tentacles of individuals that have washed up on beaches. The inflammatory response resulting from stings is due to the release of histamines from mast cells within the victim.
Negative Impacts: injures humans (bites or stings, venomous )
The Portuguese Man-of-War is eaten by some fish and crustaceans (e.g. the sand crab) that can be of commercial value.
The Portuguese Man-of-War traps its food in its tentacles. It feeds 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% of the prey are fish.
The tentacles, or dactylozooids, are the Man-of-War's main mechanisms for catching its prey and are also used for defense. P. physalis 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.
This species has been found in the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Caribbean, and the Sargasso Sea. It floats on or near the surface of the water.
Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
The Portuguese man-of-war floats on the surface of tropical, marine waters. Generally, these colonies live in warm tropical and subtropical water such as along the Florida Keys and Atlantic coast, 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.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: pelagic ; coastal
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 gametes for reproduction. Cnidocytes (stinging cells) are located in the tentacles. Their action is based on their individual osmotic and hydrostatic pressure. 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.
The stinging cells, or cnidocytes, are the characteristic food-getting mechanisms of jellyfish and their close relatives. P. physalis has two sizes of cnidocytes, some small and others are large. These cells retain their potency long after an individual has been washed up along the shore, as many hikers along beaches have discovered to their dismay and discomfort.
Other Physical Features: ectothermic ; heterothermic ; radial symmetry ; venomous
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.
Physalia are dioecious. Their larvae probably develop very rapidly to small floating forms.
Fertilization of P. physalis is assumed to occur in the open water, because gametes 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.
Germ Cell Development
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. 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.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Parental Investment: no parental involvement
The Portuguese man o' war (Physalia physalis), also known as the man-of-war,[6] is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or bluebottle, which is found mainly in the Pacific Ocean.[7] The Portuguese man o' war is the only species in the genus Physalia, which in turn is the only genus in the family Physaliidae.[8]
The Portuguese man o' war is a conspicuous member of the neuston, the community of organisms that live at the ocean surface. It has numerous venomous microscopic nematocysts which deliver a painful sting powerful enough to kill fish, and has been known to occasionally kill humans. Although it superficially resembles a jellyfish, the Portuguese man o' war is in fact a siphonophore. Like all siphonophores, it is a colonial organism, made up of many smaller units called zooids.[9] All zooids in a colony are genetically identical, but fulfill specialized functions such as feeding and reproduction, and together allow the colony to operate as a single individual.
The blue bottle, Pacific man o' war or Indo-Pacific Portuguese man o' war, distinguished by a smaller float and a single long fishing tentacle, was originally considered a separate species in the same genus (P. utriculus). The name was synonymized with P. physalis in 2007, and it is now considered a regional form of the same species.[10][11]
The name man o' war comes from the man-of-war, a sailing warship,[12] and the animal's resemblance to the Portuguese version (the caravel) at full sail.[13][5][6]
The siphonophore Physalia physalis, commonly known as the Portuguese man o' war, is one of the most conspicuous, but poorly understood, members of the neuston.[9] The neuston is the floating community of ocean organisms that live at the interface between water and air. This community is exposed to a unique set of environmental conditions including prolonged exposure to intense ultraviolet light, desiccation risk, and rough sea and wave conditions.[14] Despite their tolerance for extreme environmental conditions and the very large size of this habitat, which makes up 71% of the Earth's surface and is nearly three times the area of all terrestrial habitats, very little is known about the organisms that make up this highly specialized polyphyletic community.[15][9]
The Portuguese man o' war is aptly named after a warship: it uses part of an enlarged float filled with carbon monoxide and air as a sail to travel by wind for thousands of miles, dragging behind long tentacles that deliver a deadly venomous sting to fish.[16][17] This sailing ability, combined with a painful sting and a life cycle with seasonal blooms, results in periodic mass beach strandings and occasional human envenomations, making P. physalis the most infamous siphonophore.[15][9]
The development, morphology, and colony organization of P. physalis is very different from all other siphonophores.[9] Siphonophores are a relatively understudied group of colonial hydrozoans. Colonies are composed of functionally specialized bodies (termed zooids) that are homologous to free living individuals. Most species are planktonic and are found at most depths from the deep sea to the surface of the ocean.[18][19][20] They are fragile and difficult to collect intact, and must be collected by submersible, remotely operated vehicle, by hand while blue-water diving, or in regions with localized upwellings.[21][22] However, Physalia physalis is the most accessible, conspicuous, and robust siphonophore, and as such, much has been written about this species, including the chemical composition of its float, venom (especially envenomations), occurrence, and distribution.[15][23][24] Fewer studies, however, have taken a detailed look at P. physalis structure, including development, histology of major zooids, and broader descriptions of colony arrangement.[25][26][27][28] These studies provide an important foundation for understanding the morphology, cellular anatomy, and development of this neustonis species. It can be difficult to understand the morphology, growth, and development of P. physalis within the context of siphonophore diversity, as the colony consists of highly 3-dimensional branching structures and develops very different from all other siphonophores.[9]
The bluebottle resembles a jellyfish but is actually a siphonophore, a colonial organism composed of small individual animals called zooids.[29] There are four zooids depending on each other for survival and performing different functions, such as digestion (gastrozooids), reproduction (gonozooids) and hunting (dactylozooids). The last zooid, the pneumatophore, is a gas-filled float or sac that supports the other zooids and acts like a sail so the bluebottle is constrained to the ocean surface, moving at the mercy of the wind, waves and marine currents. The bluebottle's long tentacles hang below the float as they drift, fishing for prey to sting and drag up to their digestive zooids.[29][30]
The species is found throughout the world's oceans, in tropical, subtropical and (occasionally) temperate regions.[9][30]
Like all siphonophores, the Portuguese man o' war is colonial: each man o' war is composed of many smaller units (zooids) that hang in clusters from under a large, gas-filled structure called the pneumatophore.[31] New zooids are added by budding as the colony grows. As many as seven different kinds of zooids have been described in the man o' war: three of the medusoid type (gonophores, nectophores, and vestigial nectophores) and four of the polypoid type (free gastrozooids, tentacle-bearing zooids, gonozooids and gonopalpons).[32] However, naming and categorization of zooids varies between authors, and much of the embryonic and evolutionary relationships of zooids remains unclear.[9]
The pneumatophore, or bladder, is the most conspicuous part of the man o' war. It is translucent and tinged blue, purple, pink, or mauve, and may be 9 to 30 cm (3.5 to 11.8 in) long and rise as high as 15 cm (6 in) above the water. The pneumatophore functions as both a flotation device and a sail for the colony, allowing the colony to move with the prevailing wind.[9][31] The gas in the pneumatophore is part carbon monoxide (0.5–13%), which is actively produced by the animal, and part atmospheric gases (nitrogen, oxygen and noble gases) that diffuse in from the surrounding air.[33] In the event of a surface attack, the pneumatophore can be deflated, allowing the colony to temporarily submerge.[34]
The colony hunts and feeds through the cooperation of two types of zooid: gastrozooids and tentacle-bearing zooids known as dactylozooids[9] or tentacular palpons. The dactylozooids are equipped with tentacles, which are typically about 10 m (30 ft) in length but can reach over 30 m (100 ft).[35][36] Each tentacle bears tiny, coiled, thread-like structures called nematocysts. Nematocysts trigger and inject venom on contact, stinging, paralyzing, and killing adult or larval squids and fishes. Large groups of Portuguese man o' war, sometimes over 1,000 individuals, may deplete fisheries.[32][34] Contraction of tentacles drags the prey upward, into range of the gastrozooids, the digestive zooids. The gastrozooids surround and digest the food by secreting enzymes. P. physalis typically has multiple stinging tentacles, but a regional form (previously known as a separate species, P. utriculus) has only a single stinging tentacle.
The main reproductive zooids, the gonophores, are situated on branching structures called gonodendra. Gonophores produce sperm or eggs (see life cycle). Besides gonophores, each gonodendron also contains several other types of specialized zooids: gonozooids (which are accessory gastrozooids), nectophores (which have been speculated to allow detached gonodendra to swim), and vestigial nectophores (also called jelly polyps; the function of these is unclear).[9]
The man o' war is described as a colonial organism because the individual zooids in a colony are evolutionarily derived from either polyps or medusae,[37] i.e. the two basic body plans of cnidarians.[38] Both of these body plans comprise entire individuals in non-colonial cnidarians (for example, a jellyfish is a medusa; a sea anemone is a polyp). All zooids in a man o' war develop from the same single fertilized egg and are therefore genetically identical; they remain physiologically connected throughout life, and essentially function as organs in a shared body. Hence, a Portuguese man o' war constitutes a single individual from an ecological perspective, but is made up of many individuals from an embryological perspective.[37]
Portuguese man o' war washed up on a beach
They are often found ashore in large groups
Found mostly in tropical and subtropical waters,[39][40] the Portuguese man-o-war lives at the surface of the ocean. The gas-filled bladder, or pneumatophore, remains at the surface, while the remainder is submerged.[41] Portuguese man-o-war have no means of propulsion, and move passively, driven by the winds, currents, and tides.
Winds can drive them into bays or onto beaches. Often, finding a single Portuguese man o' war is followed by finding many others in the vicinity.[35] The Portuguese man o' war is well known to beachgoers for the painful stings delivered by its tentacles.[30] Because they can sting while beached, the discovery of a man o' war washed up on a beach may lead to the closure of the beach.[42][43]
.jpg)
Looking down from above a man o' war, showing its sail. Sails can be left-handed or right-handed.
![The bluebottle course at zero angle of attack is dependent on the sail camber[30]](http://en.wikipedia.org/wiki/File:Bluebottle_(Physalia_physalis)_sail_camber.png)
The bluebottle course at zero angle of attack is dependent on the sail camber[30]
Despite being a common occurrence, the origin of the man o' war or bluebottle before reaching the coastline is not well understood, and neither is the way it drifts at the surface of the ocean.[30]
For each man o' war or bluebottle, the float can be oriented towards the left or the right (dimorphism), believed to be an adaptation that prevents the entire population from being washed on shore to die.[44][45] The "left-handed" bluebottles sail to the right of the wind, while the "right-handed" bluebottles sail to the left. The wind will always push the two types of bluebottles in different directions, so at most half the population will be pushed towards the coast.[44][45] Regional populations of Portuguese man o' war can have substantial differences in float size and the number of long tentacles used for hunting. The regional form previously known as P. utriculus, the bluebottle, has a float rarely exceeding 10 cm in length and has one long hunting tentacle that is less than 3 m long. In comparison, the typical man o' war has a float of around 15 cm, reported up to 30 cm, and several hunting tentacles that can reach 30 m in mature colonies when fully extended.[9][30]
A Portuguese man o' war is somewhat asymmetrically shaped: the zooids of the colony hang down not quite from the midline of the pneumatophore, but offset to either the right or left side of the midline. When combined with the trailing action of the tentacles (which function as a sea anchor), this left- or right-handedness makes the colony sail sideways relative to the wind, by about 45° in either direction.[46][47] Colony handedness has therefore been theorized to affect man o' war migration, with left-handed or right-handed colonies potentially being more likely to drift down particular respective sea routes.[46] While previously believed to develop as a result of what winds a colony experienced, handedness in fact emerges early in the colony's life, while it is still living below the surface of the sea.[9]
Since they cannot swim, the movement of the man o' war or bluebottle can be modelled mathematically by calculating the forces acting on it, or by advecting virtual particles in ocean and atmospheric circulation models. Earlier studies modelled the movement of the man o' war with Lagrangian particle tracking to explain major beaching events. In 2017, Ferrer and Pastor were able to estimate the region of origin of a significant beaching event on the Basque coast.[48] They ran a Lagrangian model backwards in time, using wind velocity and a wind drag coefficient as drivers of the man o' war motion. They found that the region of origin was the North Atlantic subtropical gyre.[48] In 2015 Prieto et al. included both the effect of the surface currents and wind to predict the initial colony position prior to major beaching events in the Mediterranean.[49] This model assumed the man o' war was advected by the surface currents, with the effect of the wind being added with a much higher wind drag coefficient of 10 percent. Similarly, in 2020 Headlam et al. used beaching and offshore observations to identify a region of origin, using the joint effects of surface currents and wind drag, for the largest mass man o' war beaching on the Irish coastline in over 150 years.[50][30] These earlier studies used numerical models in combination with simple assumptions to calculate the drift of this species, excluding complex drifting dynamics. In 2021, Lee et al. provide a parameterisation for Lagrangian modelling of the bluebottle by considering the similarities between the bluebottle and a sailboat. This allowed them to compute the hydrodynamic and aerodynamic forces acting on the bluebottle and use an equilibrium condition to create a generalised model for calculating the drifting speed and course of the bluebottle under any wind and ocean current conditions.[30]
.jpg)
Blue dragon, Glaucus atlanticus
Violet snail, Janthina janthina
The Portuguese man o' war is a carnivore.[35] Using its venomous tentacles, a man o' war traps and paralyzes its prey while "reeling" it inwards to the digestive polyps. It typically feeds on small adult fish and fish fry (young fish), and sometimes zooplankton, shrimp and other small crustaceans.[51]
The organism has few predators of its own; one example is the loggerhead turtle, which feeds on the Portuguese man o' war as a common part of its diet.[52] The turtle's skin, including that of its tongue and throat, is too thick for the stings to penetrate. Also, the blue sea slug Glaucus atlanticus specializes in feeding on the Portuguese man o' war,[53] as does the violet snail Janthina janthina.[54] The ocean sunfish's diet, once thought to consist mainly of jellyfish, has been found to include many species, the Portuguese man o' war being one such example.[55][56]
The blanket octopus is immune to the venom of the Portuguese man o' war; young individuals have been observed to carry broken man o' war tentacles,[57] which males and immature females rip off and use for offensive and defensive purposes.[58]
The man-of-war fish, Nomeus gronovii, is a driftfish native to the Atlantic, Pacific and Indian Oceans. It is notable for its ability to live within the deadly tentacles of the Portuguese man o' war, upon whose tentacles and gonads it feeds. Rather than using mucus to prevent nematocysts from firing, as is seen in some of the clownfish sheltering among sea anemones, the fish appears to use highly agile swimming to physically avoid tentacles.[59][60] The fish has a very high number of vertebrae (41), which may add to its agility[60] and primarily uses its pectoral fins for swimming—a feature of fish that specialize in maneuvering tight spaces. It also has a complex skin design and at least one antibody to the man o' war's toxins.[60] Although the fish seems to be 10 times more resistant to the toxin than other fish, it can be stung by the dactylozooides (large tentacles), which it actively avoids.[59] The smaller gonozooids do not seem to sting the fish and the fish is reported to frequently "nibble" on these tentacles.[59]
The Portuguese man o' war is often found with a variety of other marine fish, including yellow jack. These fish benefit from the shelter from predators provided by the stinging tentacles, and for the Portuguese man o' war, the presence of these species may attract other fish to eat.[61]
Man o' war individuals are dioecious, meaning each colony is either male or female.[31][9] Gonophores producing either sperm or eggs (depending on the sex of the colony) sit on a tree-like structure called a gonodendron, which is believed to drop off from the colony during reproduction.[9] Mating takes place primarily in the autumn, when eggs and sperm are shed from gonophores into the water.[31] As neither fertilization nor early development have been directly observed in the wild, it is not yet known at what depth they occur.[9]
A fertilized man o' war egg develops into a larva that buds off new zooids as it grows, gradually forming a new colony. This development initially occurs under the water, and has been reconstructed by comparing different stages of larvae collected at sea.[9] The first two structures to emerge are the pneumatophore (sail) and a single, early feeding zooid called a protozooid; later, gastrozooids and tentacle-bearing zooids are added. Eventually, the growing pneumatophore becomes buoyant enough to carry the immature colony on the surface of the water.[9]
The stinging, venom-filled nematocysts in the tentacles of the Portuguese man o' war can paralyze small fish and other prey.[24] Detached tentacles and dead specimens (including those that wash up on shore) can sting just as painfully as those of the live organism in the water and may remain potent for hours or even days after the death of the organism or the detachment of the tentacle.[62]
Stings usually cause severe pain to humans, leaving whip-like red welts on the skin that normally last two or three days after the initial sting. The pain normally subsides after about one to three hours (depending on the victim's biology). However, the venom can travel to the lymph nodes and may cause symptoms that mimic an allergic reaction, including swelling of the larynx, airway blockage, cardiac distress and an inability to breathe. Other symptoms may include fever and shock and, in some extreme cases, even death,[63] although this is extremely rare. Medical attention for those exposed to large numbers of tentacles may become necessary to relieve pain or open airways if the pain becomes excruciating or lasts for more than three hours, or if breathing becomes difficult. Instances in which the stings completely surround the trunk of a young child are among those that may be fatal.[64]
The species is responsible for up to 10,000 human stings in Australia each summer, particularly on the east coast, with some others occurring off the coast of South Australia and Western Australia.[65]
Stings from a Portuguese man o' war can result in severe dermatitis characterized by long, thin, open wounds that resemble those caused by a whip.[66] These are not caused by any impact or cutting action, but by irritating urticariogenic substances in the tentacles.[67][68]
In 2017, vinegar (acetic acid, 5% acidity) rinsing (irreversibly inhibiting cnidae discharge), then applying heat, water or hot pack, at 45 °C (113 °F), for 45 minutes, was found to be the most effective treatment, while rinsing with seawater, cold packs, urine, baking soda, shaving cream, soap, lemon juice, alcohol, rubbing alcohol, and cola will trigger the release of more venom.[69]
In 2009, isolated studies had suggested that in some individuals vinegar dousing may increase toxin delivery and worsen symptoms.[70][71] In 1988, vinegar was claimed to provoke hemorrhaging when used on the less severe stings of cnidocytes of smaller species.[72]
Man o' war warning sign, Hawaii
Portuguese man o' war, Miami Beach, Florida, March 2008
Portuguese man o' war, Palm Beach, Florida, May 2013
Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. 
The name comes from a resemblance of the animal to a sailing warship, the Portuguese man-of-war (the caravel c. 1500) The Portuguese man o' war (Physalia physalis), also known as the man-of-war, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or bluebottle, which is found mainly in the Pacific Ocean. The Portuguese man o' war is the only species in the genus Physalia, which in turn is the only genus in the family Physaliidae.
The Portuguese man o' war is a conspicuous member of the neuston, the community of organisms that live at the ocean surface. It has numerous venomous microscopic nematocysts which deliver a painful sting powerful enough to kill fish, and has been known to occasionally kill humans. Although it superficially resembles a jellyfish, the Portuguese man o' war is in fact a siphonophore. Like all siphonophores, it is a colonial organism, made up of many smaller units called zooids. All zooids in a colony are genetically identical, but fulfill specialized functions such as feeding and reproduction, and together allow the colony to operate as a single individual.
