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The Portuguese war (''Physalia physalis''), also known as the man-of-war or bluebottle, is a marine
hydrozoa Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomy (biology), taxonomic class (biology), class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline wat ...
n found in the
Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
and the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
. It is the only species in the genus ''Physalia'', which in turn is the only genus in the family Physaliidae. The name ''man o’ war'' comes from the
man-of-war In Royal Navy jargon, a man-of-war (also man-o'-war, or simply man) was a powerful warship or frigate of the 16th to the 19th century, that was frequently used in Europe. Although the term never acquired a specific meaning, it was usually rese ...
, a sailing warship, and the animal's resemblance to the Portuguese version (the caravel) at full sail. The man o' war are part of the
neuston Neuston, also called pleuston, are organisms that live at the surface of a body of water, such as an ocean, estuary, lake, river, wetland or pond. Neuston can live on top of the water surface or submersed just below the water surface. In additio ...
, organisms that live on the surface of the water. A gas-filled bladder provides buoyancy that lets the animal stay afloat on the surface of the water while tentacles which can be up to165 ft (9 to 50 m) long hang below the surface, containing venomous cnidocytes that help capture prey. The cnidocytes can deliver a sting powerful enough to kill fish, and even, in some cases, humans. A sail on the bladder, which may be left or right-handed, propels it about the sea, often in groups. Although it superficially resembles a
jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...
, the Portuguese man o' war is in fact a
siphonophore Siphonophorae (from Ancient Greek σίφων (siphōn), meaning "tube" and -φόρος (-phóros), meaning "bearing") is an order within Hydrozoa, a class of marine organisms within the phylum Cnidaria. According to the World Register of Marine ...
. Like all siphonophores, it is a
colonial organism In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger pre ...
, made up of many smaller units called
zooid A zooid or zoöid is an animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooids can ...
s. Although they are morphologically quite different, all of the zooids in a single specimen are genetically identical. These different types of zooids fulfill specialized functions, such as hunting, digestion and reproduction, and together they allow the colony to operate as a single individual. Because it frequently washes up on beaches on the coast of the Atlantic, Indian and Pacific Oceans and is seen in the open ocean, the man o' war is the best-known genus of siphonophore, as nearly all siphonophores live in the cold, dark ocean depths where they can only be observed in their natural habitat by a submersible or ROV.


Taxonomy

''Physalia physalis'' is the only species in its genus, ''Physalia'', and family, Physaliidae. The Pacific man o' war, distinguished by a smaller float and a single long fishing
tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...
, was originally considered a separate
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
in the same
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
(''P. utriculus''). However, it and other supposed ''Physalia'' species are now considered synonyms of ''P. physalis.''


Description

Like all siphonophores, ''P. physalis'' is a colonial organism: each animal is composed of many smaller units (
zooid A zooid or zoöid is an animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooids can ...
s) that hang in clusters from under a large, gas-filled structure called the pneumatophore. The individual
zooid A zooid or zoöid is an animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooids can ...
s in a colony are evolutionarily derived from either polyps or
medusae Jellyfish, also known as sea jellies or simply jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals, althoug ...
, i.e. the two basic body plans of
cnidaria Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...
ns. Both of these body plans comprise entire individuals in non-colonial cnidarians (for example, a
jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...
is a medusa, while a
sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. 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 organism from an
ecological Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...
perspective, but is made up of many individuals from an
embryological Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, ''-logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos an ...
perspective. Seven different types of zooids have been described in the man o' war, and these all depend on each other for survival and performing different functions, such as digestion (
gastrozooid {{Short pages monitor * Chondrophore


References


External links


Siphonophores.org
General information
Portuguese Man-of-War
National Geographic ''National Geographic'' (formerly ''The National Geographic Magazine'', sometimes branded as ''Nat Geo'') is an American monthly magazine published by National Geographic Partners. The magazine was founded in 1888 as a scholarly journal, nine ...

Bluebottle
Life In The Fast Lane
PortugueseManOfWar.com

''Physalia physalis''
discussed on RNZ
Critter of the Week ''Critter of the Week'' is a weekly RNZ National programme about endangered and neglected native plants and animals of New Zealand. Beginning in 2015, ''Critter of the Week'' is an approximately 15-minute discussion between Nicola Toki (origi ...
, 24 December 2021. {{Authority control Physaliidae Animals described in 1758 Cnidarians of the Atlantic Ocean Cnidarians of the Caribbean Sea Cnidarians of the Indian Ocean Cnidarians of the Pacific Ocean Taxa named by Carl Linnaeus Venomous animals Colonial animals