portuguese man o' war portuguese man o' war 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 blue bottle, 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. portuguese man o' war scientific classification kingdom: animalia phylum: cnidaria class: hydrozoa order: siphonophorae suborder: cystonectae family: physaliidaebrandt, 1835 genus: physalialamarck, 1801 species: p. physalis binomial name physalia physalis(linnaeus, 1758) synonyms family-level synonym physalidae brandt, 1835 (original spelling) genus-level synonyms arethusa oken, 1815 holothuria linnaeus, 1758 physalis tilesius, 1810 physsophora modéer, 1789 species-level synonyms arethusa caravell oken, 1815 holothuria velificans osbeck, 1765 medusa utriculus gmelin, 1788 physalia australis péron, 1807 physalia gigantea bory de st vincent, 1894 physalia glauca tilesius, 1810 physalia megalista lesueur & petit physalia pelagica lamarck, 1801 physalia pelasgica bosc, 1802 physalia utriculus gmelin, 1788 physalis afer tilesius, 1810 physalis arethusa tilesius, 1810 physalis cornuta tilesius, 1810 physalis elongata lamarck, 1816 physalis glauca tilesius, 1810 physalis lamartinieri tilesius, 1810 physalis megalista lamarck, 1816 physalis osbeckii tilesius, 1810 physalis pelagica tilesius, 1810 physalis pelagica lamarck, 1816 physalis tuberculosa lamarck, 1816 physsophora physalis modéer, 1789 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 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. taxonomy 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. etymology the name man o' war comes from the man-of-war, a sailing warship, and the animal's resemblance to the portuguese version (the caravel) at full sail. overview 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. 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. 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. 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. 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. the development, morphology, and colony organization of p. physalis is very different from all other siphonophores. 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. 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. 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. fewer studies, however, have taken a detailed look at p. physalis structure, including development, histology of major zooids, and broader descriptions of colony arrangement. 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. the bluebottle resembles a jellyfish but is actually a siphonophore, a colonial organism composed of small individual animals called zooids. 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. the species is found throughout the world's oceans, in tropical, subtropical and (occasionally) temperate regions. anatomy and physiology anatomy of a physalia physalis colony with descriptions of the function of each zooid 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. 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). however, naming and categorization of zooids varies between authors, and much of the embryonic and evolutionary relationships of zooids remains unclear. 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. 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. in the event of a surface attack, the pneumatophore can be deflated, allowing the colony to temporarily submerge. the colony hunts and feeds through the cooperation of two types of zooid: gastrozooids and tentacle-bearing zooids known as dactylozooids 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). 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. 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). coloniality 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, i.e. the two basic body plans of cnidarians. 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. distribution portuguese man o' war washed up on a beach they are often found ashore in large groups found mostly in tropical and subtropical waters, 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. 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. the portuguese man o' war is well known to beachgoers for the painful stings delivered by its tentacles. 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. drifting dynamics 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 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. left- and right-handedness 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. 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. 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. 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. 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. 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. mathematical modelling since they cannot swim, the movement of the man o' war or bluebottle can be modelled mathematically by calculating the