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Ants are
eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 mil ...
insect Insects (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in ...

insect
s of the
family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social territory, typically subject to the same Politic ...
Formicidae and, along with the related
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The ...

wasp
s and
bee Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

bee
s, belong to the
order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, and the habit of achieving a ...
Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Para ...

Hymenoptera
. Ants appear in the
fossil record A fossil (from Classical Latin: , literally 'obtained by digging') is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, Seashell, shells, exoskeletons, stone imprints of a ...
across the globe in considerable diversity during the latest
Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& ...
and early
Late Cretaceous The Late Cretaceous (100.5–66 Year#SI prefix multipliers, Ma) is the younger of two epoch (geology), epochs into which the Cretaceous geological period, Period is divided in the geologic time scale. Stratum, Rock strata from this epoch form the ...
, suggesting an earlier origin. Ants evolved from vespoid
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The ...

wasp
ancestors in the
Cretaceous The Cretaceous ( ) is a geological period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form elements of a hierarchy of division ...

Cretaceous
period, and diversified after the rise of
flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

flowering plant
s. More than 13,800 of an estimated total of 22,000
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
have been classified. They are easily identified by their geniculate (elbowed)
antenna Antenna (pl. antennas or antennae) may refer to: Science and engineering * Antenna (radio) In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal con ...
e and the distinctive node-like structure that forms their slender waists. Ants form
colonies In political science, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the metropole, metropolitan ...

colonies
that range in size from a few dozen predatory individuals living in small natural cavities to highly organised colonies that may occupy large territories and consist of millions of individuals. Larger colonies consist of various castes of sterile, wingless females, most of which are workers (ergates), as well as soldiers (dinergates) and other specialised groups. Nearly all ant colonies also have some fertile males called "drones" and one or more fertile females called "
queens Queens is a borough of New York City, coextensive with Queens County, in the U.S. state of New York. It is the largest borough of New York City New York City (NYC), often simply called New York, is the List of United States cities by po ...
" (
gyne The gyne is the primary reproductive female caste Caste is a form of social stratification Social stratification refers to a society's categorization of its people into groups based on Socioeconomic status, socioeconomic factors like wealth ...
s). The colonies are described as
superorganism A superorganism or supraorganism is a group of synergetically interacting organisms of the same species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a ...
s because the ants appear to operate as a unified entity, collectively working together to support the colony. Ants have colonised almost every landmass on
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
. The only places lacking
indigenous Indigenous may refer to: *Indigenous peoples Indigenous peoples, also referred to as First people, Aboriginal people, Native people, or autochthonous people, are culturally distinct ethnic groups who are native to a particular place. The term ' ...
ants are
Antarctica Antarctica ( or ) is Earth's southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Oc ...

Antarctica
and a few remote or inhospitable islands. Ants thrive in most ecosystems and may form 15–25% of the
terrestrial animal Terrestrial animals are animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. A ...
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
. Their success in so many environments has been attributed to their social organisation and their ability to modify habitats, tap resources, and defend themselves. Their long
co-evolution In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well a ...
with other species has led to
mimetic
mimetic
,
commensal Commensalism is a long-term biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their phy ...

commensal
,
parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...

parasitic
, and mutualistic relationships. Ant societies have
division of labour The division of labour is the separation of tasks in any economic system An economic system, or economic order, is a system A system is a group of interacting Interaction is a kind of action that occurs as two or more objects have an ...
, communication between individuals, and an ability to
solve complex problems
solve complex problems
. These parallels with
human societies A society is a group of individuals involved in persistent social interaction In social science, a social relation or social interaction is any relationship between two or more individuals. Social relations derived from individual agenc ...

human societies
have long been an inspiration and subject of study. Many human cultures make use of ants in cuisine, medication, and rituals. Some species are valued in their role as
biological pest control Biological control or biocontrol is a method of controlling pests such as insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was ...
agents. Their ability to exploit resources may bring ants into conflict with humans, however, as they can damage crops and invade buildings. Some species, such as the
red imported fire ant The red imported fire ant (''Solenopsis invicta''), also known as the fire ant or RIFA, is a species of ant native to South America. A member of the genus ''Fire ant, Solenopsis'' in the subfamily Myrmicinae, it was Species description, describ ...
(''Solenopsis invicta''), are regarded as
invasive species An invasive species is an introduced organism that becomes overpopulated and negatively alters its new environment. Although their spread can have beneficial aspects, invasive species adversely affect the invaded habitat Ibex in an ...
, establishing themselves in areas where they have been introduced accidentally.


Etymology

The word ''ant'' and its chiefly dialectal form ''emmet'' come from ', ' of
Middle English Middle English (abbreviated to ME) was a form of the English language English is a West Germanic language of the Indo-European language family The Indo-European languages are a language family A language is a structured sys ...
, which come from ' of
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language English is a West Germanic language of the Indo-European language family The Indo-European languages are a language family A language ...
, and these are all related to the dialectal
Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () *Dutch language , spoken in Belgium (also referred as ''flemish'') Dutch may also refer to:" Castle * Dutch Castle Places * ...
' and the
Old High German Old High German (OHG, german: Althochdeutsch, German abbr. ) is the earliest stage of the German language German ( Standard High German: , ) is a West Germanic language mainly spoken in Central Europe Central Europe is an area of Euro ...
', from which comes the modern
German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany, see also German nationality law * German language The German la ...

German
'. All of these words come from West Germanic ''*'', and the original meaning of the word was "the biter" (from
Proto-Germanic Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the reconstructed Reconstruction may refer to: Politics, history, and sociology *Reconstruction (law), the transfer of a company's (or several companies') business to a new ...
', "off, away" + ' "cut"). The family name Formicidae is derived from the
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, it became ...

Latin
' ("ant") from which the words in other
Romance languages The Romance languages, less commonly Latin or Neo-Latin languages, are the modern languages that evolved from Vulgar Latin Vulgar Latin, also known as Popular or Colloquial Latin, is non-literary Literature broadly is any collection of w ...

Romance languages
, such as the Portuguese ', Italian ', Spanish ', Romanian ', and French ' are derived. It has been hypothesised that a
Proto-Indo-European Proto-Indo-European (PIE) is the theorized common ancestor of the Indo-European language family The Indo-European languages are a language family A language is a structured system of communication used by humans, including speech ( ...
word *morwi- was used, cf.
Sanskrit Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language of South Asia that belongs to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor langua ...

Sanskrit
''vamrah'',
Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
μύρμηξ ''mýrmēx'',
Old Church Slavonic Old Church Slavonic or Old Slavonic () was the first Slavic literary language A literary language is the form of a language A language is a structured system of communication used by humans, including speech (spoken language), gestures (S ...
''mraviji'',
Old Irish Old Irish (''Goídelc''; ga, Sean-Ghaeilge; gd, Seann Ghàidhlig; gv, Shenn Yernish or ; Old Irish: ᚌᚑᚔᚇᚓᚂᚉ), sometimes called Old Gaelic, is the oldest form of the Goidelic The Goidelic or Gaelic languages ( ga, teangacha ...
''moirb'',
Old Norse Old Norse, Old Nordic, or Old Scandinavian is a stage of development of North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia Scandinavia; : ''Skades ...
''maurr'',
Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () *Dutch language , spoken in Belgium (also referred as ''flemish'') Dutch may also refer to:" Castle * Dutch Castle Places * ...
''mier'',
Swedish Swedish or ' may refer to: * Anything from or related to Sweden, a country in Northern Europe * Swedish language, a North Germanic language spoken primarily in Sweden and Finland * Swedish alphabet, the official alphabet used by the Swedish langua ...
''myra'',
Danish Danish may refer to: * Something of, from, or related to the country of Denmark * A national or citizen of Denmark, also called a "Dane", see Demographics of Denmark * Danish people or Danes, people with a Danish ancestral or ethnic identity * Danis ...
''myre'',
Middle Dutch Middle Dutch is a collective name for a number of closely related West Germanic The West Germanic languages constitute the largest of the three branches of the Germanic languages, Germanic family of languages (the others being the North German ...
''miere'',
Crimean Gothic Crimean Gothic was an East Germanic language spoken by the Crimean Goths in some isolated locations in Crimea Crimea (; ; uk, Крим, Krym; crh, Къырым, translit=Kirim/Qırım; grc, Κιμμερία/Ταυρική, translit=K ...
'' miera''.


Taxonomy and evolution

The family Formicidae belongs to the order
Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Para ...

Hymenoptera
, which also includes
sawflies Sawflies are the insects of the suborder In biological classification, the order ( la, wikt:ordo#Latin, ordo) is # a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. The well-known ranks in des ...
,
bee Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

bee
s, and
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The ...

wasp
s. Ants evolved from a lineage within the stinging wasps, and a 2013 study suggests that they are a sister group of the
Apoidea The superfamily (zoology), superfamily Apoidea is a major group within the Hymenoptera, which includes two traditionally recognized lineages, the "sphecidae, sphecoid" wasps, and the bees. Molecular phylogeny demonstrates that the bees arose from ...

Apoidea
. In 1966,
E. O. Wilson Edward Osborne Wilson (born June 10, 1929), usually cited as E. O. Wilson, is an American biologist Francesco Redi, the founder of biology, is recognized to be one of the greatest biologists of all time A biologist is a professional who has ...
and his colleagues identified the
fossil A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication used by humans, inc ...

fossil
remains of an ant ('' Sphecomyrma'') that lived in the
Cretaceous The Cretaceous ( ) is a geological period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form elements of a hierarchy of division ...

Cretaceous
period. The specimen, trapped in amber
dating Dating is a stage of romantic relationships whereby two people meet socially with the aim of each assessing the other's suitability as a prospective partner in a future intimate relationship An intimate relationship is an interpersonal re ...
back to around 92 million years ago, has features found in some wasps, but not found in modern ants. ''Sphecomyrma'' was possibly a ground forager, while '' Haidomyrmex'' and '''', related genera in subfamily
Sphecomyrminae Sphecomyrminae is an extinct subfamily of ants in family Formicidae known from a series of Cretaceous fossils found in North America, Europe, and Asia. Sphecomyrminae contains eight genera, divided into two tribes Sphecomyrmini and Zigrasimeciini. ...
, are reconstructed as active arboreal predators. Older ants in the genus ''Sphecomyrmodes'' have been found in 99 million year-old amber from
Myanmar Myanmar, ); UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, John ...

Myanmar
. A 2006 study suggested that ants arose tens of millions of years earlier than previously thought, up to 168 million years ago. After the rise of
flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

flowering plant
s about 100 million years ago they diversified and assumed ecological dominance around 60 million years ago. Some groups, such as the
Leptanillinae Leptanillinae is a subfamily of ants. They are further divided into the tribes Anomalomyrmini and Leptanillini. In all Leptanillini, the larvae feed their hemolymph to the queen through specialized processes on their prothoraces and third abdomin ...
and
Martialinae ''Martialis heureka'' is a species of ant discovered in 2000 from the Amazon rainforest near Manaus, Brazil. It was described as a new species and placed as the Monotypic taxon, sole member of a new subfamily, Martialinae. The generic name mean ...
, are suggested to have diversified from early primitive ants that were likely to have been predators underneath the surface of the soil. During the Cretaceous period, a few species of primitive ants ranged widely on the
Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea Pangaea or Pangea () was a supercontinent In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("s ...
n supercontinent (the
Northern Hemisphere The Northern Hemisphere is the half of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remain ...

Northern Hemisphere
). They were scarce in comparison to the populations of other insects, representing only about 1% of the entire insect population. Ants became dominant after
adaptive radiation In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic inte ...
at the beginning of the
Paleogene period The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous The Cretaceous (, ) is a geological period that la ...
. By the
Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define ...
and
Miocene The Miocene ( ) is the first geological epoch In geochronology, an epoch is a subdivision of the geologic timescale that is longer than an age (geology), age but shorter than a period (geology), period. The current epoch is the Holocene Epoch of ...
, ants had come to represent 20–40% of all insects found in major fossil deposits. Of the species that lived in the
Eocene The Eocene ( ) Epoch is a geological epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language belonging to the ...
epoch, around one in 10 genera survive to the present. Genera surviving today comprise 56% of the genera in
Baltic amber , Poland. The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite. It dates from 44 million years ago (during the Eocene epoch). It has been estimated that these forests created more than 100,000 tons of ...

Baltic amber
fossils (early Oligocene), and 92% of the genera in
Dominican Dominican may refer to: * Someone or something from or related to the Dominican Republic The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the C ...

Dominican
amber fossils (apparently early Miocene).Hölldobler & Wilson (1990), pp. 23–24
Termite Termites are Eusociality, eusocial insects that are classified at the Taxonomy (biology), taxonomic rank of infraorder Isoptera, or alternatively as Taxonomic rank#All ranks, epifamily Termitoidae, within the order Blattodea (along with cockroa ...

Termite
s live in colonies and are sometimes called ‘white ants’, but termites are not ants. They are the sub-order
Isoptera Termites are eusocial insects that are classified at the taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also re ...

Isoptera
, and together with
cockroach Cockroaches (or roaches) are insects of the order Blattodea, which also includes termite Termites are Eusociality, eusocial insects that are classified at the Taxonomy (biology), taxonomic rank of infraorder Isoptera, or as Taxonomic rank ...

cockroach
es they form the order
Blattodea Blattodea is an order (biology), order of insects that contains cockroaches and termites. Formerly, the termites were considered a separate order, Isoptera, but genetics, genetic and molecular evidence suggests an intimate relationship with the c ...

Blattodea
. Blattodeans are related to
mantid Mantidae is one of the largest family (biology), families in the Order (biology), order of Mantodea, praying mantises, based on the type species ''Mantis religiosa''; however, most genera are tropical or subtropical. Historically, this was the on ...
s,
crickets Crickets are Orthopteran insects which are related to Tettigoniidae, bush crickets, and, more distantly, to grasshoppers. In older literature, such as Augustus Daniel Imms, Imms,Imms AD, rev. Richards OW & Davies RG (1970) ''A General Textbook ...

crickets
, and other winged insects that do not undergo full
metamorphosis Metamorphosis is a biological process Biological processes are those processes that are vital for an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are ...
. Like ants, termites are
eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 mil ...
, with sterile workers, but they differ greatly in the genetics of reproduction. The similarity of their social structure to that of ants is attributed to
convergent evolution Convergent evolution is the independent evolution Evolution is change in the heritable Heredity, also called inheritance or biological inheritance, is the passing on of Phenotypic trait, traits from parents to their offspring; eit ...
. Velvet ants look like large ants, but are wingless female
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The ...

wasp
s.


Distribution and diversity

Ants are found on all continents except
Antarctica Antarctica ( or ) is Earth's southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Oc ...

Antarctica
, and only a few large islands, such as
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an autonomous territory An autonomous administrative division (also referred to as an autonomous area, entity, unit, region, subdivision, or territory) is a subnational administra ...

Greenland
,
Iceland Iceland ( is, Ísland; ) is a Nordic Nordic most commonly refers to: * Nordic countries, written in plural as Nordics, the northwestern European countries, including Scandinavia, Fennoscandia and the List of islands in the Atlantic Ocean#N ...

Iceland
, parts of
Polynesia Polynesia (, ; from grc, πολύς "many" and grc, νῆσος "island") ( to, Faka-Polinisia; mi, Porinihia; haw, Polenekia; fj, Kai-Polinesia; sm, Polenisia; rar, Porinetia; ty, Pōrīnetia; tvl, Polenisia; tkl, Polenihia) is a ...

Polynesia
and the
Hawaiian Islands The Hawaiian Islands ( haw, Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, numerous smaller islets, and seamounts in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island o ...

Hawaiian Islands
lack native ant species. Ants occupy a wide range of
ecological niche In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms ...

ecological niche
s and exploit many different food resources as direct or indirect herbivores, predators and scavengers. Most ant species are omnivorous generalists, but a few are specialist feeders. Their ecological dominance is demonstrated by their
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
: ants are estimated to contribute 15–20 % (on average and nearly 25% in the tropics) of terrestrial animal biomass, exceeding that of the
vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an indiv ...
s. Ants range in size from ,Hölldobler & Wilson (1990), p. 589 the largest species being the fossil '''', the queen of which was long with a wingspan of . Ants vary in colour; most ants are red or black, but a few species are green and some tropical species have a metallic lustre. More than 13,800 species are currently knownAntWeb
/ref> (with upper estimates of the potential existence of about 22,000; see the article List of ant genera), with the greatest diversity in the tropics. Taxonomic studies continue to resolve the classification and systematics of ants. Online databases of ant species, includin
AntWeb
and th
Hymenoptera Name Server
help to keep track of the known and newly described species. The relative ease with which ants may be sampled and studied in
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

ecosystem
s has made them useful as
indicator species A bioindicator is any species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of orga ...
in
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
studies.


Morphology

Ants are distinct in their
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
from other insects in having geniculate (elbowed)
antenna Antenna (pl. antennas or antennae) may refer to: Science and engineering * Antenna (radio) In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal con ...
e,
metapleural gland Metapleural glands (also called metasternal or metathoracic glands) are secretory glands that are unique to ant Ants are eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el ...
s, and a strong constriction of their second
abdominal The abdomen (colloquially called the belly, tummy, midriff or stomach) is the part of the body between the thorax The thorax or chest is a part of the anatomy of humans, mammals, other tetrapod animals located between the neck and the abdomen. I ...

abdominal
segment into a node-like
petiole Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy), the narrow waist of some hymenopteran insects {{disambiguation ...
. The head,
mesosoma The mesosoma is the middle part of the body, or tagma (biology), tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the arthropod leg, legs, and, in the case of winged insects, th ...
, and
metasoma The metasoma is the posterior part of the body, or tagma (biology), tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory sys ...
are the three distinct body segments (formally tagmata). The petiole forms a narrow waist between their mesosoma (
thorax The thorax or chest is a part of the anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Bioc ...
plus the first abdominal segment, which is fused to it) and gaster (abdomen less the abdominal segments in the petiole). The petiole may be formed by one or two nodes (the second alone, or the second and third abdominal segments). Like other insects, ants have an
exoskeleton An exoskeleton (from Greek έξω, ''éxō'' "outer" and σκελετός, ''skeletós'' "skeleton") is the external skeleton A skeleton is a structural frame that supports an animal Animals (also called Metazoa) are multicellular ...

exoskeleton
, an external covering that provides a protective casing around the body and a point of attachment for muscles, in contrast to the internal skeletons of humans and other
vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an indiv ...
s. Insects do not have
lung The lungs are the primary organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchyma ...

lung
s;
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
and other gases, such as
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
, pass through their exoskeleton via tiny valves called spiracles. Insects also lack closed
blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system An organ system is a biological system A biological system is a comp ...
s; instead, they have a long, thin, perforated tube along the top of the body (called the "
dorsal aorta The dorsal aortae are paired (left and right) embryological vessels which progress to form the descending aorta The descending aorta is part of the aorta, the largest artery in the Human body, body. The descending aorta begins at the aortic arch ...
") that functions like a heart, and pumps
haemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a substance used by an organism to survive, grow, and reprod ...
toward the head, thus driving the circulation of the internal fluids. The
nervous system In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mecha ...

nervous system
consists of a
ventral nerve cord The ventral nerve cord (VNC) is a major structure of the invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all ani ...
that runs the length of the body, with several
ganglia A ganglion is a group of neuron cell bodies in the peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system In Biology, biology, the nervous system is a Complex system, high ...

ganglia
and branches along the way reaching into the extremities of the appendages.Borror, Triplehorn & Delong (1989), pp. 24–71


Head

An ant's head contains many
sensory organs Sense relates to any of the systems and corresponding organs involved in sensation, i.e. the physical process of responding to stimuli and providing data Data are units of information Information can be thought of as the resolution of ...
. Like most insects, ants have
compound eye as imaged by an electron microscope A compound eye is a Eye, visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidium, ommatidia, which are tiny independent photoreception units that consist of ...

compound eye
s made from numerous tiny lenses attached together. Ant eyes are good for acute movement detection, but do not offer a high
resolution Resolution(s) may refer to: Common meanings * Resolution (debate), the statement which is debated in policy debate * Resolution (law), a written motion adopted by a deliberative body * New Year's resolution, a commitment that an individual make ...
image. They also have three small
ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye Eyes are organs of the visual system The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photorecept ...

ocelli
(simple eyes) on the top of the head that detect light levels and
polarization Polarization or polarisation may refer to: In the physical sciences *Polarization (waves), the ability of waves to oscillate in more than one direction, in particular polarization of light, responsible for example for the glare-reducing effect of ...
. Compared to
vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an indiv ...
s, ants tend to have blurrier eyesight, particularly in smaller species, and a few
subterranean Subterranean(s) or The Subterranean(s) may refer to: * Subterranea (geography), underground structures, both natural and man-made Literature * Subterranean (novel), ''Subterranean'' (novel), a 1998 novel by James Rollins * ''Subterranean Magazi ...
taxa are completely
blind Blind may refer to: * The state of Visual impairment, blindness, being unable to see * A window blind, a covering for a window Blind may also refer to: Arts, entertainment, and media Films * Blind (2007 film), ''Blind'' (2007 film), a 2007 Dut ...
. However, some ants, such as Australia's bulldog ant, have excellent vision and are capable of discriminating the distance and size of objects moving nearly a
metre The metre ( Commonwealth spelling) or meter (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English ...
away. Two
antennae Antenna (pl. antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two coll ...
("feelers") are attached to the head; these organs detect chemicals, air currents, and vibrations; they also are used to transmit and receive signals through touch. The head has two strong jaws, the Mandible (insect), mandibles, used to carry food, manipulate objects, construct nests, and for defence. In some species, a small pocket (infrabuccal chamber) inside the mouth stores food, so it may be passed to other ants or their larvae.


Mesosoma

Both the arthropod leg, legs and insect wing, wings of the ant are attached to the
mesosoma The mesosoma is the middle part of the body, or tagma (biology), tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the arthropod leg, legs, and, in the case of winged insects, th ...
("thorax"). The legs terminate in a hooked Chelae, claw which allows them to hook on and climb surfaces. Only reproductive ants- Queen (insect), queens, and males, have wings. Queens shed their wings after the nuptial flight, leaving visible stubs, a distinguishing feature of queens. In a few species, wingless queens (ergatoids) and males occur.


Metasoma

The
metasoma The metasoma is the posterior part of the body, or tagma (biology), tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory sys ...
(the "abdomen") of the ant houses important internal organs, including those of the reproductive, respiratory (tracheae), and excretory systems. Workers of many species have their ovipositor, egg-laying structures modified into stinger (organ), stings that are used for subduing predation, prey and defending their nests.


Polymorphism

In the colonies of a few ant species, there are physical castes—workers in distinct size-classes, called minor, median, and major ergates. Often, the larger ants have disproportionately larger heads, and correspondingly stronger mandible (insect), mandibles. These are known as macrergates while smaller workers are known as micrergates. Although formally known as dinergates, such individuals are sometimes called "soldier" ants because their stronger mandibles make them more effective in fighting, although they still are workers and their "duties" typically do not vary greatly from the minor or median workers. In a few species, the median workers are absent, creating a sharp divide between the minors and majors. Weaver ants, for example, have a distinct bimodal size distribution. Some other species show continuous variation in the size of workers. The smallest and largest workers in ''Pheidologeton diversus'' show nearly a 500-fold difference in their dry-weights. Workers cannot mate; however, because of the haplodiploid sex-determination system in ants, workers of a number of species can lay unfertilised eggs that become fully fertile, haploid males. The role of workers may change with their age and in some species, such as honeypot ants, young workers are fed until their gasters are distended, and act as living food storage vessels. These food storage workers are called ''repletes''. For instance, these replete workers develop in the North American honeypot ant ''Myrmecocystus mexicanus''. Usually the largest workers in the colony develop into repletes; and, if repletes are removed from the colony, other workers become repletes, demonstrating the flexibility of this particular Polymorphism (biology), polymorphism. This polymorphism in morphology and behaviour of workers initially was thought to be determined by environmental factors such as nutrition and hormones that led to different morphogenesis, developmental paths; however, genetic differences between worker castes have been noted in ''Acromyrmex'' sp. These polymorphisms are caused by relatively small genetic changes; differences in a single gene of ''Solenopsis invicta'' can decide whether the colony will have single or multiple queens. The Australian jack jumper ant (''Myrmecia pilosula'') has only a single pair of chromosomes (with the males having just one chromosome as they are haploid), the lowest number known for any animal, making it an interesting subject for studies in the genetics and developmental biology of social insects.


Life cycle

The life of an ant starts from an egg; if the egg is fertilised, the progeny will be female diploid, if not, it will be male haploid. Ants develop by complete metamorphosis with the larva stages passing through a pupal stage before emerging as an adult. The larva is largely immobile and is fed and cared for by workers. Food is given to the larvae by trophallaxis, a process in which an ant Regurgitation (digestion), regurgitates liquid food held in its Crop (anatomy), crop. This is also how adults share food, stored in the "social stomach". Larvae, especially in the later stages, may also be provided solid food, such as trophic eggs, pieces of prey, and seeds brought by workers. The larvae grow through a series of four or five moults and enter the pupal stage. The pupa has the appendages free and not fused to the body as in a Chrysalis, butterfly pupa. The differentiation into queens and workers (which are both female), and different caste (biology), castes of workers, is influenced in some species by the nutrition the larvae obtain. Genetic influences and the polyphenism, control of gene expression by the developmental environment are complex and the determination of caste continues to be a subject of research. Winged male ants, called drones (termed "aner" in old literature), emerge from pupae along with the usually winged breeding females. Some species, such as army ants, have wingless queens. Larvae and pupae need to be kept at fairly constant temperatures to ensure proper development, and so often are moved around among the various brood chambers within the colony. A new ergate spends the first few days of its adult life caring for the queen and young. She then graduates to digging and other nest work, and later to defending the nest and foraging. These changes are sometimes fairly sudden, and define what are called temporal castes. An explanation for the sequence is suggested by the high casualties involved in foraging, making it an acceptable risk only for ants who are older and are likely to die soon of natural causes. Ant colonies can be long-lived. The queens can live for up to 30 years, and workers live from 1 to 3 years. Males, however, are more transitory, being quite short-lived and surviving for only a few weeks. Ant queens are estimated to live 100 times as long as solitary insects of a similar size. Ants are active all year long in the tropics, but, in cooler regions, they survive the winter in a state of dormancy known as hibernation. The forms of inactivity are varied and some temperate species have larvae going into the inactive state (diapause), while in others, the adults alone pass the winter in a state of reduced activity.


Reproduction

A wide range of reproductive strategies have been noted in ant species. Females of many species are known to be capable of reproducing asexually through thelytoky, thelytokous parthenogenesis. Secretions from the male accessory glands in some species can plug the female genital opening and prevent females from re-mating. Most ant species have a system in which only the queen and breeding females have the ability to mate. Contrary to popular belief, some ant nests have multiple queens, while others may exist without queens. Workers with the ability to reproduce are called "gamergates" and colonies that lack queens are then called gamergate colonies; colonies with queens are said to be queen-right. Drones can also mate with existing queens by entering a foreign colony, such as in Army ant, army ants. When the drone is initially attacked by the workers, it releases a mating pheromone. If recognized as a mate, it will be carried to the queen to mate. Males may also patrol the nest and fight others by grabbing them with their mandibles, piercing their
exoskeleton An exoskeleton (from Greek έξω, ''éxō'' "outer" and σκελετός, ''skeletós'' "skeleton") is the external skeleton A skeleton is a structural frame that supports an animal Animals (also called Metazoa) are multicellular ...

exoskeleton
and then marking them with a pheromone. The marked male is interpreted as an invader by worker ants and is killed. Most ants are univoltine, producing a new generation each year. During the species-specific breeding period, winged females and winged males, known to entomologists as alates, leave the colony in what is called a nuptial flight. The nuptial flight usually takes place in the late spring or early summer when the weather is hot and humid. Heat makes flying easier and freshly fallen rain makes the ground softer for mated queens to dig nests. Males typically take flight before the females. Males then use visual cues to find a common mating ground, for example, a landmark such as a pine tree to which other males in the area converge. Males secrete a mating pheromone that females follow. Males will mount females in the air, but the actual mating process usually takes place on the ground. Females of some species mate with just one male but in others they may mate with as many as ten or more different males, storing the Spermatozoon, sperm in their spermathecae.Hölldobler & Wilson (1990), pp. 143–179 Mated females then seek a suitable place to begin a colony. There, they break off their wings using their tibial spurs and begin to lay and care for eggs. The females can selectively fertilise future eggs with the sperm stored to produce diploid workers or lay unfertilized haploid eggs to produce drones. The first workers to hatch are known as nanitics, and are weaker and smaller than later workers, but they begin to serve the colony immediately. They enlarge the nest, forage for food, and care for the other eggs. Species that have multiple queens may have a queen leaving the nest along with some workers to found a colony at a new site, a process akin to Swarming (honey bee), swarming in honeybees.


Behaviour and ecology


Communication

Ants communicate with each other using pheromones, sounds, and touch. The use of pheromones as chemical signals is more developed in ants, such as the red harvester ant, than in other hymenopteran groups. Like other insects, ants perceive smells with their long, thin, and mobile antennae. The paired antennae provide information about the direction and intensity of scents. Since most ants live on the ground, they use the soil surface to leave pheromone trails that may be followed by other ants. In species that forage in groups, a forager that finds food marks a trail on the way back to the colony; this trail is followed by other ants, these ants then reinforce the trail when they head back with food to the colony. When the food source is exhausted, no new trails are marked by returning ants and the scent slowly dissipates. This behaviour helps ants deal with changes in their environment. For instance, when an established path to a food source is blocked by an obstacle, the foragers leave the path to explore new routes. If an ant is successful, it leaves a new trail marking the shortest route on its return. Successful trails are followed by more ants, reinforcing better routes and gradually identifying the best path. Ants use pheromones for more than just making trails. A crushed ant emits an alarm pheromone that sends nearby ants into an attack frenzy and attracts more ants from farther away. Several ant species even use "propaganda pheromones" to confuse enemy ants and make them fight among themselves. Pheromones are produced by a wide range of structures including Dufour's glands, poison glands and glands on the hindgut, pygidium, rectum, sternum, and hind tibia. Pheromones also are exchanged, mixed with food, and passed by trophallaxis, transferring information within the colony. This allows other ants to detect what task group (e.g., foraging or nest maintenance) other colony members belong to. In ant species with queen castes, when the dominant queen stops producing a specific pheromone, workers begin to raise new queens in the colony.Hölldobler & Wilson (1990), p. 354 Some ants produce sounds by stridulation, using the gaster segments and their mandibles. Sounds may be used to communicate with colony members or with other species.


Defence

Ants attack and defend themselves by biting and, in many species, by stinging, often injecting or spraying chemicals, such as formic acid in the case of formicine ants, alkaloids and piperidines in fire ants, and a variety of protein components in other ants. Paraponera clavata, Bullet ants (''Paraponera clavata, Paraponera''), located in Central America, Central and South America, are considered to have the most painful sting of any insect, although it is usually not fatal to humans. This sting is given the highest rating on the Schmidt sting pain index. The sting of jack jumper ants can be fatal, and an antivenom has been developed for it. Fire ants, ''Fire ant, Solenopsis'' spp., are unique in having a venom sac containing piperidine alkaloids. Their stings are painful and can be dangerous to hypersensitive people. Trap-jaw ants of the genus ''Odontomachus'' are equipped with mandibles called trap-jaws, which snap shut faster than any other predatory appendages within the animalia, animal kingdom. One study of ''Odontomachus bauri'' recorded peak speeds of between , with the jaws closing within 130 microseconds on average. The ants were also observed to use their jaws as a catapult to eject intruders or fling themselves backward to escape a threat. Before striking, the ant opens its mandibles extremely widely and locks them in this position by an internal mechanism. Energy is stored in a thick band of muscle and explosively released when triggered by the stimulation of sensory receptor, sensory organs resembling hairs on the inside of the mandibles. The mandibles also permit slow and fine movements for other tasks. Trap-jaws also are seen in the following genera: ''Anochetus'', ''Orectognathus'', and ''Strumigenys'', plus some members of the Dacetini tribe, which are viewed as examples of
convergent evolution Convergent evolution is the independent evolution Evolution is change in the heritable Heredity, also called inheritance or biological inheritance, is the passing on of Phenotypic trait, traits from parents to their offspring; eit ...
. Camponotus saundersi, A Malaysian species of ant in the ''Camponotus'' ''cylindricus'' superspecies, group has enlarged mandibular glands that extend into their gaster. If combat takes a turn for the worse, a worker may perform a final act of autothysis, suicidal altruism by rupturing the membrane of its gaster, causing the content of its mandibular glands to burst from the anterior region of its head, spraying a poisonous, corrosive secretion containing acetophenones and other chemicals that immobilise small insect attackers. The worker subsequently dies. Suicidal defences by workers are also noted in a Brazilian ant, ''Forelius pusillus'', where a small group of ants leaves the security of the nest after sealing the entrance from the outside each evening. In addition to defence against predators, ants need to protect their colonies from pathogens. Some worker ants maintain the hygiene of the colony and their activities include wikt:undertaker, undertaking or ''necrophoresis, necrophory'', the disposal of dead nest-mates. Oleic acid has been identified as the compound released from dead ants that triggers necrophoric behaviour in ''Atta mexicana'' while workers of ''Linepithema humile'' react to the absence of characteristic chemicals (dolichodial and iridomyrmecin) present on the cuticle of their living nestmates to trigger similar behaviour. Nests may be protected from physical threats such as flooding and overheating by elaborate nest architecture. Workers of ''Cataulacus muticus'', an arboreal species that lives in plant hollows, respond to flooding by drinking water inside the nest, and excreting it outside. ''Camponotus anderseni'', which nests in the cavities of wood in mangrove habitats, deals with submergence under water by switching to anaerobic respiration.


Learning

Many animals can learn behaviours by imitation, but ants may be the only group apart from mammals where interactive teaching has been observed. A knowledgeable forager of ''Temnothorax albipennis'' can lead a naïve nest-mate to newly discovered food by the process of tandem running. The follower obtains knowledge through its leading tutor. The leader is acutely sensitive to the progress of the follower and slows down when the follower lags and speeds up when the follower gets too close. Controlled experiments with colonies of ''Cerapachys biroi'' suggest that an individual may choose nest roles based on her previous experience. An entire generation of identical workers was divided into two groups whose outcome in food foraging was controlled. One group was continually rewarded with prey, while it was made certain that the other failed. As a result, members of the successful group intensified their foraging attempts while the unsuccessful group ventured out fewer and fewer times. A month later, the successful foragers continued in their role while the others had moved to specialise in brood care.


Nest construction

Complex nests are built by many ant species, but other species are nomadic and do not build permanent structures. Ants may form subterranean nests or build them on trees. These nests may be found in the ground, under stones or logs, inside logs, hollow stems, or even acorns. The materials used for construction include soil and plant matter, and ants carefully select their nest sites; ''Temnothorax albipennis'' will avoid sites with dead ants, as these may indicate the presence of pests or disease. They are quick to abandon established nests at the first sign of threats. The army ants of South America, such as the ''Eciton burchellii'' species, and the driver ants of Africa do not build permanent nests, but instead, alternate between nomadism and stages where the workers form a temporary nest (bivouac (ants), bivouac) from their own bodies, by holding each other together. Weaver ant (''Oecophylla'' spp.) workers build nests in trees by attaching leaves together, first pulling them together with bridges of workers and then inducing their larvae to produce silk as they are moved along the leaf edges. Similar forms of nest construction are seen in some species of ''Polyrhachis''. ''Formica polyctena'', among other ant species, constructs nests that maintain a relatively constant interior temperature that aids in the development of larvae. The ants maintain the nest temperature by choosing the location, nest materials, controlling ventilation and maintaining the heat from solar radiation, worker activity and metabolism, and in some moist nests, microbial activity in the nest materials. Some ant species, such as those that use natural cavities, can be opportunistic and make use of the controlled micro-climate provided inside human dwellings and other artificial structures to house their colonies and nest structures. File:AntBridge Crossing 03.jpg File:AntBridge Crossing 04.jpg File:AntBridge Crossing 08.jpg File:AntBridge Crossing 10.jpg


Cultivation of food

Most ants are generalist predators, scavengers, and indirect herbivores, but a few have evolved specialised ways of obtaining nutrition. It is believed that many ant species that engage in indirect herbivory rely on specialized symbiosis with their gut microbes to upgrade the nutritional value of the food they collect and allow them to survive in nitrogen poor regions, such as rainforest canopies. Leafcutter ants (''Atta (genus), Atta'' and ''Acromyrmex'') feed exclusively on a fungus that grows only within their colonies. They continually collect leaves which are taken to the colony, cut into tiny pieces and placed in fungal gardens. Ergates specialise in related tasks according to their sizes. The largest ants cut stalks, smaller workers chew the leaves and the smallest tend the fungus. Leafcutter ants are sensitive enough to recognise the reaction of the fungus to different plant material, apparently detecting chemical signals from the fungus. If a particular type of leaf is found to be toxic to the fungus, the colony will no longer collect it. The ants feed on structures produced by the fungi called ''gongylidia''. Symbiosis, Symbiotic bacteria on the exterior surface of the ants produce antibiotics that kill bacteria introduced into the nest that may harm the fungi.


Navigation

Forage, Foraging ants travel distances of up to from their nest and scent trails allow them to find their way back even in the dark. In hot and arid regions, day-foraging ants face death by desiccation, so the ability to find the shortest route back to the nest reduces that risk. Diurnal desert ants of the genus ''Cataglyphis'' such as the Sahara desert ant navigate by keeping track of direction as well as distance travelled. Distances travelled are measured using an internal pedometer that keeps count of the steps taken and also by evaluating the movement of objects in their visual field (optical flow). Directions are measured using the position of the sun. They path integration, integrate this information to find the shortest route back to their nest. Like all ants, they can also make use of visual landmarks when available as well as olfactory and tactile cues to navigate. Some species of ant are able to use the Earth's magnetic field for navigation. The compound eyes of ants have specialised cells that detect polarised light from the Sun, which is used to determine direction. These polarization detectors are sensitive in the ultraviolet region of the light spectrum. In some army ant species, a group of foragers who become separated from the main column may sometimes turn back on themselves and form a circular ant mill. The workers may then run around continuously until they die of exhaustion.


Locomotion

The female worker ants do not have wings and reproductive females lose their wings after their mating flights in order to begin their colonies. Therefore, unlike their wasp ancestors, most ants travel by walking. Some species are capable of leaping. For example, Jerdon's jumping ant (''Harpegnathos saltator'') is able to jump by synchronising the action of its mid and hind pairs of legs. There are several species of gliding ant including ''Cephalotes atratus''; this may be a common trait among arboreal ants with small colonies. Ants with this ability are able to control their horizontal movement so as to catch tree trunks when they fall from atop the forest canopy. Other species of ants can form chains to bridge gaps over water, underground, or through spaces in vegetation. Some species also form floating rafts that help them survive floods. These rafts may also have a role in allowing ants to colonise islands. ''Polyrhachis sokolova'', a species of ant found in Australian mangrove swamps, can swim and live in underwater nests. Since they lack gills, they go to trapped pockets of air in the submerged nests to breathe.


Cooperation and competition

Not all ants have the same kind of societies. The Australian bulldog ants are among the biggest and most basal (phylogenetics), basal of ants. Like virtually all ants, they are
eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 mil ...
, but their social behaviour is poorly developed compared to other species. Each individual hunts alone, using her large eyes instead of chemical senses to find prey. Some species (such as ''Tetramorium caespitum'') attack and take over neighbouring ant colonies. Others are less expansionist, but just as aggressive; they invade colonies to steal eggs or larvae, which they either eat or raise as workers or slaves. Extreme specialists among these slave-raiding ants, such as the Polyergus, Amazon ants, are incapable of feeding themselves and need captured workers to survive. Captured workers of enslaved ''Temnothorax'' species have evolved a counter-strategy, destroying just the female pupae of the slave-making ''Temnothorax americanus'', but sparing the males (who do not take part in slave-raiding as adults). Ants identify kin and nestmates through their scent, which comes from hydrocarbon-laced secretions that coat their exoskeletons. If an ant is separated from its original colony, it will eventually lose the colony scent. Any ant that enters a colony without a matching scent will be attacked. Also, the reason why two separate colonies of ants will attack each other even if they are of the same species is because the genes responsible for pheromone production are different between them. The Argentine ant, however, does not have this characteristic, due to lack of genetic diversity, and has become a global pest because of it. Parasitic ant species enter the colonies of host ants and establish themselves as social parasites; species such as ''Strumigenys xenos'' are entirely parasitic and do not have workers, but instead, rely on the food gathered by their ''Strumigenys perplexa'' hosts. This form of parasitism is seen across many ant genera, but the parasitic ant is usually a species that is closely related to its host. A variety of methods are employed to enter the nest of the host ant. A parasitic queen may enter the host nest before the first brood has hatched, establishing herself prior to development of a colony scent. Other species use pheromones to confuse the host ants or to trick them into carrying the parasitic queen into the nest. Some simply fight their way into the nest.Hölldobler & Wilson (1990), pp. 436–448 A sexual conflict, conflict between the sexes of a species is seen in some species of ants with these reproducers apparently competing to produce offspring that are as closely related to them as possible. The most extreme form involves the production of clonal offspring. An extreme of sexual conflict is seen in ''Wasmannia auropunctata'', where the queens produce diploid daughters by thelytokous parthenogenesis and males produce clones by a process whereby a diploid egg loses its maternal contribution to produce haploid males who are clones of the father.


Relationships with other organisms

Ants form symbiotic associations with a range of species, including other ant species, other insects, plants, and fungi. They also are preyed on by many animals and even certain fungi. Some arthropod species spend part of their lives within ant nests, either preying on ants, their larvae, and eggs, consuming the food stores of the ants, or avoiding predators. These inquilines may bear a close resemblance to ants. The nature of this ant mimicry (myrmecomorphy) varies, with some cases involving Batesian mimicry, where the mimic reduces the risk of predation. Others show Wasmannian mimicry, a form of mimicry seen only in inquilines. Aphids and other hemipteran insects secrete a sweet liquid called Honeydew (secretion), honeydew, when they feed on plant sap. The sugars in honeydew are a high-energy food source, which many ant species collect. In some cases, the aphids secrete the honeydew in response to ants tapping them with their antennae. The ants in turn keep predators away from the aphids and will move them from one feeding location to another. When migrating to a new area, many colonies will take the aphids with them, to ensure a continued supply of honeydew. Ants also tend mealybugs to harvest their honeydew. Mealybugs may become a serious pest of pineapples if ants are present to protect mealybugs from their natural enemies. Myrmecophile, Myrmecophilous (ant-loving) caterpillars of the butterfly family Lycaenidae (e.g., blues, coppers, or hairstreaks) are herded by the ants, led to feeding areas in the daytime, and brought inside the ants' nest at night. The caterpillars have a gland which secretes honeydew when the ants massage them. Some caterpillars produce vibrations and sounds that are perceived by the ants. A similar adaptation can be seen in Grizzled skipper butterflies that emit vibrations by expanding their wings in order to communicate with ants, which are natural predators of these butterflies. Other caterpillars have evolved from ant-loving to ant-eating: these myrmecophagous caterpillars secrete a pheromone that makes the ants act as if the caterpillar is one of their own larvae. The caterpillar is then taken into the ant nest where it feeds on the ant larvae. A number of specialized bacteria have been found as endosymbionts in ant guts. Some of the dominant bacteria belong to the order Rhizobiales whose members are known for being nitrogen-fixing symbionts in legumes but the species found in ant lack the ability to fix nitrogen. Fungus-growing ants that make up the tribe Attini, including leafcutter ants, cultivate certain species of fungus in the genera ''Leucoagaricus'' or ''Leucocoprinus'' of the family Agaricaceae. In this ant-fungus mutualism, both species depend on each other for survival. The ant ''Allomerus decemarticulatus'' has evolved a three-way association with the host plant, ''Hirtella physophora'' (Chrysobalanaceae), and a sticky fungus which is used to trap their insect prey. Myrmelachista schumanni, Lemon ants make devil's gardens by killing surrounding plants with their stings and leaving a pure patch of lemon ant trees, (''Duroia hirsuta''). This modification of the forest provides the ants with more nesting sites inside the stems of the ''Duroia'' trees. Although some ants obtain nectar from flowers, pollination by ants is somewhat rare, one example being of the pollination of the orchid ''Leporella fimbriata'' which induces male ''Myrmecia urens'' to pseudocopulate with the flowers, transferring pollen in the process. One theory that has been proposed for the rarity of pollination is that the secretions of the metapleural gland inactivate and reduce the viability of pollen. Some plants have special nectar exuding structures, Extrafloral nectary, extrafloral nectaries, that provide food for ants, which in turn plant defense against herbivory, protect the plant from more damaging herbivorous insects. Species such as the bullhorn acacia (''Acacia cornigera'') in Central America have hollow thorns that house colonies of stinging ants (''Pseudomyrmex ferruginea'') who defend the tree against insects, browsing mammals, and Epiphyte, epiphytic vines. Isotopic labelling studies suggest that plants also obtain nitrogen from the ants. In return, the ants obtain food from protein- and lipid-rich Beltian bodies. In Fiji ''Philidris nagasau'' (Dolichoderinae) are known to selectively grow species of epiphytic ''Squamellaria'' (Rubiaceae) which produce large domatia inside which the ant colonies nest. The ants plant the seeds and the domatia of young seedling are immediately occupied and the ant faeces in them contribute to rapid growth. Similar dispersal associations are found with other dolichoderines in the region as well. Another example of this type of ectosymbiosis comes from the ''Macaranga'' tree, which has stems adapted to house colonies of ''Crematogaster'' ants. Many plant species have seeds that are adapted for dispersal by ants. Seed#Seed dispersal, Seed dispersal by ants or myrmecochory is widespread, and new estimates suggest that nearly 9% of all plant species may have such ant associations. Often, seed-dispersing ants perform directed dispersal, depositing the seeds in locations that increase the likelihood of seed survival to reproduction. Some plants in arid, fire-prone systems are particularly dependent on ants for their survival and dispersal as the seeds are transported to safety below the ground. Many ant-dispersed seeds have special external structures, elaiosomes, that are sought after by ants as food. A Convergent evolution, convergence, possibly a form of mimicry, is seen in the eggs of stick insects. They have an edible elaiosome-like structure and are taken into the ant nest where the young hatch. Most ants are predatory and some prey on and obtain food from other social insects including other ants. Some species specialise in preying on termites (''Megaponera'' and ''Termitopone'') while a few Cerapachyinae prey on other ants. Some termites, including ''Nasutitermes corniger'', form associations with certain ant species to keep away predatory ant species. The tropical wasp ''Mischocyttarus drewseni'' coats the pedicel of its nest with an ant-repellent chemical. It is suggested that many tropical wasps may build their nests in trees and cover them to protect themselves from ants. Other wasps, such as ''Agelaia multipicta, A. multipicta'', defend against ants by blasting them off the nest with bursts of wing buzzing. Stingless bees (''Trigona'' and ''Melipona'') use chemical defences against ants. Flies in the Old World genus ''Bengalia'' (Calliphoridae) predator, prey on ants and are kleptoparasites, snatching prey or brood from the mandibles of adult ants. Wingless and legless females of the Malaysian phoridae, phorid fly (''Vestigipoda myrmolarvoidea'') live in the nests of ants of the genus ''Aenictus'' and are cared for by the ants. Fungi in the genera ''Cordyceps'' and ''Ophiocordyceps'' infect ants. Ants react to their infection by climbing up plants and sinking their mandibles into plant tissue. The fungus kills the ants, grows on their remains, and produces a fruiting body. It appears that the fungus alters the behaviour of the ant to help disperse its spores in a microhabitat that best suits the fungus. Strepsipteran parasites also manipulate their ant host to climb grass stems, to help the parasite find mates. A nematode (''Myrmeconema neotropicum'') that infects canopy ants (''Cephalotes atratus'') causes the black-coloured gasters of workers to turn red. The parasite also alters the behaviour of the ant, causing them to carry their gasters high. The conspicuous red gasters are mistaken by birds for ripe fruits, such as ''Hyeronima alchorneoides'', and eaten. The droppings of the bird are collected by other ants and fed to their young, leading to further spread of the nematode. South American poison dart frogs in the genus ''Dendrobates'' feed mainly on ants, and the toxins in their skin may come from the ants. Army ants forage in a wide roving column, attacking any animals in that path that are unable to escape. In Central and South America, ''Eciton burchellii'' is the swarming ant most commonly attended by "ant-follower, ant-following" birds such as antbirds and woodcreepers. This behaviour was once considered mutualistic, but later studies found the birds to be
parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...

parasitic
. Direct kleptoparasitism (birds stealing food from the ants' grasp) is rare and has been noted in Inca doves which pick seeds at nest entrances as they are being transported by species of ''Pogonomyrmex''. Birds that follow ants eat many prey insects and thus decrease the foraging success of ants. Birds indulge in a peculiar behaviour called Anting (bird activity), anting that, as yet, is not fully understood. Here birds rest on ant nests, or pick and drop ants onto their wings and feathers; this may be a means to remove ectoparasites from the birds. Anteaters, aardvarks, pangolins, echidnas and numbats have special adaptations for living on a diet of ants. These adaptations include long, sticky tongues to capture ants and strong claws to break into ant nests. Brown bears (''Ursus arctos'') have been found to feed on ants. About 12%, 16%, and 4% of their faecal volume in spring, summer and autumn, respectively, is composed of ants.


Relationship with humans

Ants perform many ecological roles that are beneficial to humans, including the suppression of Pest (organism), pest populations and aeration of the soil. The use of weaver ants in citrus cultivation in southern China is considered one of the oldest known applications of biological control.Hölldobler & Wilson (1990), pp. 619–629 On the other hand, ants may become nuisances when they invade buildings, or cause economic losses. In some parts of the world (mainly Africa and South America), large ants, especially army ants, are used as surgical sutures. The wound is pressed together and ants are applied along it. The ant seizes the edges of the wound in its mandibles and locks in place. The body is then cut off and the head and mandibles remain in place to close the wound. The large heads of the dinergates (soldiers) of the leafcutting ant ''Atta cephalotes'' are also used by native surgeons in closing wounds. Some ants have toxic venom and are of Ants of medical importance, medical importance. The species include ''Paraponera clavata'' (tocandira) and ''Dinoponera'' spp. (false tocandiras) of South America and the ''Myrmecia'' ants of Australia. In South Africa, ants are used to help harvest the seeds of rooibos (''Aspalathus linearis''), a plant used to make a herbal tea. The plant disperses its seeds widely, making manual collection difficult. Black ants collect and store these and other seeds in their nest, where humans can gather them ''en masse''. Up to half a pound (200 g) of seeds may be collected from one ant-heap. Although most ants survive attempts by humans to eradicate them, a few are highly endangered. These tend to be island species that have evolved specialized traits and risk being displaced by introduced ant species. Examples include the critically endangered Sri Lankan relict ant (''Aneuretus simoni'') and ''Adetomyrma venatrix'' of Madagascar. It has been estimated by
E. O. Wilson Edward Osborne Wilson (born June 10, 1929), usually cited as E. O. Wilson, is an American biologist Francesco Redi, the founder of biology, is recognized to be one of the greatest biologists of all time A biologist is a professional who has ...
that the total number of individual ants alive in the world at any one time is between one and ten 1,000,000,000,000,000, quadrillion (short scale) (i.e., between 1015 and 1016). According to this estimate, the total
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
of all the ants in the world is approximately equal to the total biomass of the entire human race. According to this estimate, there are also approximately 1 million ants for every human on Earth.


As food

Ants and their larvae are eaten in different parts of the world. The eggs of two species of ants are used in Mexican ''escamoles''. They are considered a form of insect caviar and can sell for as much as US$40 per pound ($90/kg) because they are seasonal and hard to find. In the Colombian department of Santander Department, Santander, ''hormigas culonas'' (roughly interpreted as "large-bottomed ants") ''Atta laevigata'' are toasted alive and eaten. In areas of India, and throughout Burma and Thailand, a paste of the green weaver ant (''Oecophylla smaragdina'') is served as a condiment with curry. Oecophylla, Weaver ant eggs and larvae, as well as the ants, may be used in a Thai salad, ''yam'' ( th, ยำ), in a dish called ''yam khai mot daeng'' ( th, ยำไข่มดแดง) or red ant egg salad, a dish that comes from the Issan or north-eastern region of Thailand. William Saville-Kent, Saville-Kent, in the ''Naturalist in Australia'' wrote "Beauty, in the case of the green ant, is more than skin-deep. Their attractive, almost sweetmeat-like translucency possibly invited the first essays at their consumption by the human species". Mashed up in water, after the manner of lemon squash, "these ants form a pleasant acid drink which is held in high favor by the natives of North Queensland, and is even appreciated by many European palates". In his ''First Summer in the Sierra'', John Muir notes that the Mono people, Digger Indians of California ate the tickling, acid gasters of the large jet-black carpenter ants. The Mexican Indians eat the replete workers, or living honey-pots, of the honey ant (''Myrmecocystus'').


As pests

Some ant species are considered as pests, primarily those that occur in human habitations, where their presence is often problematic. For example, the presence of ants would be undesirable in sterile places such as hospitals or kitchens. Some species or genera commonly categorized as pests include the Argentine ant, pavement ant, yellow crazy ant, banded sugar ant, pharaoh ant, Formica rufa, red wood ant, black carpenter ant, Tapinoma sessile, odorous house ant,
red imported fire ant The red imported fire ant (''Solenopsis invicta''), also known as the fire ant or RIFA, is a species of ant native to South America. A member of the genus ''Fire ant, Solenopsis'' in the subfamily Myrmicinae, it was Species description, describ ...
, and Myrmica rubra, European fire ant. Some ants will raid stored food, some will seek water sources, others may damage indoor structures, some may damage agricultural crops directly (or by aiding sucking pests). Some will sting or bite. The adaptive nature of ant colonies make it nearly impossible to eliminate entire colonies and most pest management practices aim to control local populations and tend to be temporary solutions. Ant populations are managed by a combination of approaches that make use of chemical, biological, and physical methods. Chemical methods include the use of insecticidal bait which is gathered by ants as food and brought back to the nest where the poison is inadvertently spread to other colony members through trophallaxis. Management is based on the species and techniques may vary according to the location and circumstance.


In science and technology

Observed by humans since the dawn of history, the behaviour of ants has been documented and the subject of early writings and fables passed from one century to another. Those using scientific methods, Myrmecology, myrmecologists, study ants in the laboratory and in their natural conditions. Their complex and variable social structures have made ants ideal model organisms. Ultraviolet vision was first discovered in ants by John Lubbock, 1st Baron Avebury, Sir John Lubbock in 1881. Studies on ants have tested hypotheses in ecology and sociobiology, and have been particularly important in examining the predictions of theories of kin selection and Evolutionarily stable strategy, evolutionarily stable strategies. Ant colonies may be studied by rearing or temporarily maintaining them in ''formicarium, formicaria'', specially constructed glass framed enclosures. Individuals may be tracked for study by marking them with dots of colours. The successful techniques used by ant colonies have been studied in computer science and robotics to produce distributed and fault-tolerant systems for solving problems, for example Ant colony optimization and Ant robotics. This area of biomimetics has led to studies of ant locomotion, search engines that make use of "foraging trails", fault-tolerant storage, and networking algorithms.


As pets

From the late 1950s through the late 1970s, formicarium, ant farms were popular educational children's toys in the United States. Some later commercial versions use transparent gel instead of soil, allowing greater visibility at the cost of stressing the ants with unnatural light.


In culture

Anthropomorphism, Anthropomorphised ants have often been used in fables and children's stories to represent industriousness and cooperative effort. They also are mentioned in religious texts. In the Book of Proverbs in the Bible, ants are held up as a good example for humans for their hard work and cooperation. Aesop did the same in his fable The Ant and the Grasshopper. In the Quran, Solomon, Sulayman is said to have heard and understood an ant warning other ants to return home to avoid being accidentally crushed by Sulayman and his marching army. In parts of Africa, ants are considered to be the messengers of the deities. Some Native American mythology, such as the Hopi mythology, considers ants as the very first animals. Ant bites are often said to have curative properties. The sting of some species of ''Pseudomyrmex'' is claimed to give fever relief. Ant bites are used in the initiation ceremonies of some Amazon Indian cultures as a test of endurance. Ant society has always fascinated humans and has been written about both humorously and seriously. Mark Twain wrote about ants in his 1880 book ''A Tramp Abroad''. Some modern authors have used the example of the ants to comment on the relationship between society and the individual. Examples are Robert Frost in his poem "Departmental" and T. H. White in his fantasy novel ''The Once and Future King''. The plot in French entomologist and writer Bernard Werber's ''Les Fourmis'' science-fiction trilogy is divided between the worlds of ants and humans; ants and their behaviour is described using contemporary scientific knowledge. H.G. Wells wrote about intelligent ants destroying human settlements in Brazil and threatening human civilization in his 1905 science-fiction short story, ''Empire of the Ants, The Empire of the Ants.'' In more recent times, animated cartoons and 3-D animated films featuring ants have been produced including ''Antz'', ''A Bug's Life'', ''The Ant Bully (film), The Ant Bully'', ''The Ant and the Aardvark'', ''Ferdy the Ant (TV series), Ferdy the Ant'' and ''Atom Ant.'' Renowned Myrmecology, myrmecologist
E. O. Wilson Edward Osborne Wilson (born June 10, 1929), usually cited as E. O. Wilson, is an American biologist Francesco Redi, the founder of biology, is recognized to be one of the greatest biologists of all time A biologist is a professional who has ...
wrote a short story, "Trailhead" in 2010 for ''The New Yorker'' magazine, which describes the life and death of an ant-queen and the rise and fall of her colony, from an ants' point of view. The French neuroanatomist, psychiatrist and Eugenics, eugenicist Auguste Forel believed that ant societies were models for human society. He published a five volume work from 1921 to 1923 that examined ant biology and society. In the early 1990s, the video game ''SimAnt'', which simulated an ant colony, won the 1992 Software and Information Industry Association#CODiE Awards, Codie award for "Best Simulation Program". Ants also are quite popular inspiration for many science-fiction insectoids, such as the Formics of ''Ender's Game'', the Bugs of ''Starship Troopers'', the giant ants in the films ''Them!'' and ''Empire of the Ants (film), Empire of the Ants,'' Marvel Comics' super hero Ant-Man, and ants mutated into super-intelligence in ''Phase IV (1974 film), Phase IV''. In computer strategy games, ant-based species often benefit from increased production rates due to their single-minded focus, such as the Klackons in the ''Master of Orion'' series of games or the ChCht in ''Deadlock II''. These characters are often credited with a Group mind (science fiction), hive mind, a common misconception about ant colonies.


See also

* Ant venom * Glossary of ant terms * International Union for the Study of Social Insects * ''Myrmecological News'' (journal) * Task allocation and partitioning of social insects


References


Cited texts

* *


Further reading

* * *


External links


AntWeb from The California Academy of Sciences

AntWiki – Bringing Ants to the World

Ant Species Fact Sheets
from the National Pest Management Association on Argentine, Carpenter, Pharaoh, Odorous, and other ant species
Ant Genera of the World – distribution maps


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