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Ant

2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and
Fish

                    iAnts
   Formica rufa worker
   Formica rufa worker
          Scientific classification

   Kingdom:     Animalia
   Phylum:      Arthropoda
   Subphylum:   Hexapoda
   Class:       Insecta
   Subclass:    Pterygota
   Infraclass:  Neoptera
   Superorder:  Endopterygota
   Order:       Hymenoptera
   Suborder:    Apocrita
   Superfamily: Vespoidea
   Family:      Formicidae
                Latreille 1809

                                 Subfamilies

     * Aenictinae
     * Aenictogitoninae
     * Aneuretinae
     * Apomyrminae
     * Cerapachyinae
     * Dolichoderinae
     * Dorylinae
     * Ecitoninae
     * Formicinae
     * Leptanillinae
     * Leptanilloidinae
     * Myrmeciinae
     * Myrmicinae
     * Nothomyrmeciinae
     * Ponerinae
     * Pseudomyrmecinae

   Enlarge
   Diagram of a worker ant (Pachycondyla verenae).
   Enlarge
   Diagram of a worker ant (Pachycondyla verenae).
   This closeup shows the prominent mandibles and the comparatively small
   compound eyes.
   Enlarge
   This closeup shows the prominent mandibles and the comparatively small
   compound eyes.

   Ants are one of the most successful groups of insects in the animal
   kingdom. They are of particular interest because they are social
   insects and form highly organized colonies or nests which sometimes
   consist of millions of individuals. Colonies of invasive ant species
   will sometimes work together and form super-colonies, spanning a very
   wide area of land. Ant colonies are sometimes described as
   superorganisms because they appear to operate as a single entity.

   Ants have colonized almost every landmass on Earth. They can constitute
   up to 15% of the total animal biomass of a tropical rainforest; in the
   Amazon the combined weight of the ants is said to be four times larger
   than that of the tetrapods in the same area. It has also been estimated
   that the combined weight of all ants exceeds the weight of mankind.

   As of 2006, there are 11,880 known ant species, most of which reside in
   hot climates.

Ancestry

   Ants are classified as a family, Formicidae, belonging to the order
   Hymenoptera which also includes sawflies, bees and wasps. Ants are a
   lineage derived from within the vespoid wasps. Phylogenetic analysis
   indicates that ants evolved from other groups of wasps in the
   Cretaceous period about 120 to 170 million years ago. After the rise of
   angiosperms about 100 million years ago, ant evolution also showed
   rapid change, and by about 60 million years ago ants had moved to
   ecological dominance . Several fossils from the Cretaceous are
   intermediate in form between wasps and ants, further confirming the
   wasp ancestry of ants. Like other Hymenoptera, the genetic system
   employed by ants is Haplodiploidy.

   In 1966 E. O. Wilson et al. obtained the first remains of an ant from
   the Cretaceous, Sphecomyrma freyi. The specimen was trapped in amber
   that was more than eighty million years old. This species provides
   evidence of a link between modern ants and non-social wasps. Cretaceous
   ants shared a couple of wasp-like traits together with modern ant-like
   characteristics.

   During the Cretaceous times, representatives of only a few species of
   primitive ants ranged widely on what was the super-continent Laurasia
   (the northern hemisphere). They were scarce in comparison to other
   insects (about only 1%). It was adaptive radiation which gave ants the
   dominance at the beginning of the Tertiary Period. Of the species
   extant in the Cretaceous and Eocene eras, only 1 of about 10 genera is
   now extinct. 56% of the genera represented on the Baltic amber fossils
   (early Oligocene), and 96% of the genera represented in the Dominican
   amber fossils (apparently early Miocene) still survive today.

Morphology

   Ants are distinguished from other insects by the following traits:
   elbowed antennae; a strongly constricted second abdominal segment
   forming a distinct node-like petiole; the petiole can be formed by one
   or two "parts" or segments (only the second, or the second and third
   abdominal segments can form it). Ants have a wingless worker caste; the
   presence of a metapleural gland is also distinctive.

   Ant bodies, like other insects, have an exoskeleton, meaning their
   bodies are externally covered in a protective casing, as opposed to the
   internal skeletal framework of humans and other vertebrates. Ants do
   not have lungs. Oxygen passes through tiny pores, the spiracles, in
   their exoskeleton - the same holes through which carbon dioxide leaves
   their body. Nor do they have a heart; a colorless blood, the hemolymph,
   runs from their head to rear and back again along a long tube. Their
   nervous system is much like a human spinal cord in that it is a
   continuous cord, the ventral nerve cord, from head to rear with
   branches into each extremity.

   There are three main divisions to an ant's anatomy: the head, mesosoma
   and metasoma:

   The head of an ant has many important parts. Ant eyes are compound
   eyes, similar to fly eyes: they have many smaller eyes attached
   together which enables them to see movement very well. Most ants have
   poor to mediocre eyesight; some are blind altogether. A few have
   exceptional vision though, such as Australia's bulldog ant. Also
   attached to the head of an ant are two feelers. The feelers are special
   smelling organs that help ants communicate. Ants release pheromones
   (chemicals that have different smells) to communicate with each other
   and the feelers pick these smells as signals. The head also has two
   strong pinchers, the mandibles, which are used to carry food, to dig,
   and to defend. There is also a small pocket inside the mouth where ants
   can store food and give to others in need.

   The thorax of the ant is where all six legs are attached. At the end of
   each leg is a sharp claw that helps ants climb and hang onto things.
   Most queens and male ants have wings, which they drop after the nuptial
   flight; however wingless queens (ergatoids) and males can occur.

   The metasoma of the ant houses many of the important internal organs.
   Some species of ants have stingers used for subduing prey and defending
   their nests.

Development

   The life of an ant starts with an egg. If the egg is fertilized, the
   ant will be female; if not, it will be male. Ants are holometabolous,
   and develop by complete metamorphosis, passing through larval and pupal
   stages before they become adults. The larval stage is particularly
   helpless – for instance it lacks legs entirely – and cannot care for
   itself. The difference between queens and workers (which are both
   female), and between different castes of workers when they exist, is
   determined by feeding in the larval stage. Food is given to the larvae
   by a process called trophallaxis in which an ant regurgitates food
   previously held in its crop for communal storage. This is also how
   adults distribute food amongst themselves. Larvae and pupae need to be
   kept at fairly constant temperatures to ensure proper development, and
   so are often moved around various brood chambers within the colony.

   A new worker spends the first few days of its adult life caring for the
   queen and young. After that it graduates to digging and other nest
   work, and then to foraging and defense of the nest. These changes are
   fairly abrupt and define what are called temporal castes. One theory of
   why this occurs is because foraging has a high death rate, so ants only
   participate in it when they are older and closer to death anyway. In a
   few ants there are also physical castes – workers come in a spectrum of
   sizes, called minor, median, and major workers, the latter beginning
   foraging sooner. Often the larger ants will have disproportionately
   larger heads, and so stronger mandibles. Such individuals are sometimes
   called "soldier" ants because their stronger mandibles make them more
   effective in fighting other creatures, although they are still in fact
   worker ants and their "duties" typically do not vary greatly from the
   minor or median workers. In a few species the median workers have
   disappeared, creating a sharp divide and clear physical difference
   between the minors and majors.

   Most of the common ant species breed in the same way. Only the Queen
   and breeding females have the ability to mate. Contrary to popular
   belief, some ant nests have multiple queens. The male ants, called
   drones, along with the breeding females are born with wings, and do
   nothing throughout their life except eat, until the time for mating
   comes. At this time, all breeding ants, excluding the queen, are
   carried outside where other colonies of similar species are doing the
   same. Then, all the winged breeding ants take flight. Mating occurs in
   flight and the males die shortly afterward. The females that survive
   land and seek a suitable place to begin a colony. There, they break off
   their own wings and begin to lay eggs, which they care for. Sperm
   obtained during their nuptial flight is stored and used to fertilise
   all future eggs produced. The first workers to hatch are weak 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. This is how most new colonies start. A few species that
   have multiple queens can start a new colony as a queen from the old
   nest takes a number of workers to a new site and founds a colony there.

Communication and behaviour

   Acrobat ant (Crematogaster - Myrmecidinae)
   Enlarge
   Acrobat ant (Crematogaster - Myrmecidinae)
   Ant mound hole - preventing water coming into nest during rain
   Enlarge
   Ant mound hole - preventing water coming into nest during rain

   Ant communication is accomplished primarily through chemicals called
   pheromones. Because most ants spend their time in direct contact with
   the ground, these chemical messages are more developed than in other
   Hymenopterans. So for instance, when a forager finds food, she will
   leave a pheromone trail along the ground on her way home. Home is
   typically located through the use of remembered landmarks and the
   position of the sun as detected with compound eyes and also by means of
   special sky polarization-detecting fibers within the eyes.

   In a short time other ants will follow this pheromone trail. Returning
   home, they reinforce this same trail which in turn attracts more ants
   until the food is exhausted, after which the trail is no longer
   reinforced and so slowly dissipates.

   This elementary behaviour explains how ants adapt to changes in their
   environment. When an established path to a food source is blocked by a
   new obstacle, the foragers leave the path to explore new routes. If
   successful, the returning ant leaves a new trail marking the shortest
   route. Since each ant prefers to follow a path richer in pheromone
   rather than poorer, the resulting route is also the shortest available.

   Ants make use of pheromones for other purposes as well. A crushed ant,
   for example, will emit an alarm pheromone which in high concentration
   sends nearby ants into an attack frenzy; and in lower concentration,
   merely attracts them. To confuse their enemies, several ant species
   even use what are termed propaganda pheromones.

   Like other insects, ants smell with their antennae, which are long and
   thin. These are fairly mobile, having a distinct elbow joint after an
   elongated first segment; and since they come in pairs--rather like
   binocular vision or stereophonic sound equipment--they provide
   information about direction as well as intensity. Pheromones are also
   exchanged as compounds mixed with food and passed in trophallaxis,
   giving the ants information about one another's health and nutrition.
   Ants can also detect what task group (e.g. foraging or nest
   maintenance) to which other ants belong. Of special note, the queen
   produces a certain pheromone without which the workers would begin
   raising new queens.

   Ants attack and defend themselves by biting and in many species,
   stinging, often injecting chemicals like formic acid.

   While many types of animals can learn behaviors by imitating other
   animals, ants may be the only group of animals besides primates and
   some other mammals in which interactive teaching behaviour has been
   observed. Knowledgeable forager ants of the species Temnothorax
   albipennis directly lead naive nest-mates to newly discovered food
   sources by the excruciatingly slow (and time-costly) process of "
   tandem running". The follower thereby obtains knowledge that it would
   not have, had it not been tutored, and this is at the expense of its
   nest-mate teacher. Both leader and follower are acutely sensitive to
   the progress of their partner. For example, the leader slows down when
   the follower lags too far behind, and speeds up when the follower gets
   too close, while the follower does the opposite (Franks and Richardson,
   2006).

Locomotion

   Ants usually lose, or never develop, their wings. Therefore, unlike
   their wasp ancestors, most ants travel by walking. Some tend to develop
   literal paths--the tiny equivalent of deer trails--or create unseen
   paths using chemical hints (Pheromones) left for others to smell.

   The more cooperative species of ants sometimes form chains to bridge
   gaps, whether that be over water, underground, or through spaces in
   arboreal paths.
   Harpegnathos saltator
   Enlarge
   Harpegnathos saltator

   Among their reproductive members, most species of ant do retain wings
   beyond their mating flight; most females remove their own wings when
   returning to the ground to lay eggs, while the males almost invariably
   die after that maiden flight.

   Some ants are even capable of leaping. A particularly notable species
   is Jerdon's Jumping ant ( Harpegnathos saltator).

Gliding ants

   There are several species of gliding ant. In fact this may be a common
   trait among most arboreal ants.

Ant cooperation and competition

   Some species of ants are known for attacking and taking over the
   colonies of others ant species. Others are less expansionist but
   nonetheless just as aggressive; they attack colonies to steal eggs or
   larvae, which they either eat or raise as workers/slaves. Some ants,
   such as the Amazon Ants, are incapable of feeding themselves, but must
   rely on captured worker ants to care for them. Also, sometimes young
   queens live with their birth colony.

   The tetramorium ant ( Pavement ant) is famous for its urge to increase
   its territory. In early spring, colonies attempt to conquer new areas
   and often attack the nearest enemy colony. These result in huge
   sidewalk battles, sometimes leaving thousands of ants dead. Because of
   their aggressive nature, they also tend to be very clever, often
   finding ways into seemingly impenetrable areas.

   Ants identify one another as friends through their scent, a
   hydrocarbon-laced secretion that coats their exoskeletons.

Types

   Near the Panamá Canal
   Enlarge
   Near the Panamá Canal
   Ants in Sumatran Rainforest
   Enlarge
   Ants in Sumatran Rainforest

   There is a great diversity among ants and their behaviors. They range
   in size from 2 to about 25 millimetres (about 0.08 to 1 inch). Their
   colour may vary; most are red or black, but other colors can also be
   seen, including some tropical groups with a metallic lustre.

   See list of ant genera (alphabetical) for an alphabetical compendium of
   worldwide ant genera, and antbase.org/Hymenoptera Name Serverfor a
   complete catalogue of all the currently known ant species of the world
   and their synonyms. Antbase.org/Hymenoptera Name Server is providing an
   up to date record of the actual number of species, and allows to follow
   the description of new taxa.

   Of special note:
     * Bullet Ants (Genus Paraponera), located in Central and South
       America, are the most venomous insect. Stings are incredibly
       painful, though usually non-fatal.
     * Jack jumper ants, (Myrmecia pilosula) located in Australia, are
       quite deadly to a small number of people in the population, and
       cause hospitalizations each year.
     * The Masai of Africa had an abiding respect for the Siafu Ants,
       voracious predators that consume a large amount of insects and are
       welcomed for the benefit they bring to farmers, as they will
       eliminate all pests from a crop and quickly move on.
     * Some of the more advanced ants are the army ants and driver ants,
       from South America and Africa respectively. Unlike most species
       which have permanent nests, army and driver ants do not form
       permanent nests, but instead alternate between nomadic stages and
       stages where the workers form a temporary nest ( bivouac) out of
       their own bodies. Colonies reproduce either through nuptial flights
       as described above, or by fission, where a group of workers simply
       dig a new hole and raise new queens. Colony members are
       distinguished by smell, and other intruders are usually attacked,
       with notable exceptions.
     * Some ants will raid the colonies of other ants, taking the pupae
       with them, which once hatched act as workers in the raider's
       colonies despite not being genetically related to the queen. A few
       species, such as the Amazon ants (e.g. Polyergus rufescens), have
       become utterly dependent on such slaves, to the point of being
       otherwise unable to feed themselves.
     * Some ants, called honeypot ants, have special workers called
       repletes who simply store food for the rest of the colony,
       generally becoming immobile with greatly enlarged abdomens. In hot,
       dry places, even deserts, in Africa, North America and Australia
       where they live, they are considered a great delicacy.
     * Weaver ants ( Oecophylla) build nests in trees by attaching leaves
       together, first pulling them together with bridges of workers and
       then sewing them together by pressing silk-producing larvae against
       them in alternation.
     * Leafcutter ants ( Atta and Acromyrmex) feed exclusively on a
       special fungus that lives only within their colonies. They
       continually collect leaves which they cut into tiny pieces for the
       fungus to grow on. These ants have several differently sized castes
       especially for cutting up the pieces they are supplied with into
       even smaller pieces. Leaf cutter ants are sensitive enough to adapt
       to the fungi's reaction to different plant material, apparently
       detecting chemical signals from the fungus. If a particular type of
       leaf is toxic to the fungus the colony will no longer collect it.
       The ants grow the fungus because it produces special structures
       called gongylidia which are fed on by the ants. They create
       antibiotics on their skin, and subsist entirely on this farming of
       the fungus.
     * Fire ants are unique by having a poison sac where the contents
       consists largely of piperidine alkaloids.
     * Silver ants navigate by using their eyes instead of pheromones to
       find their way back home.
     * Scientists recently discovered that Sahara desert ants have an
       internal pedometer that keeps tracks of how many steps they take,
       and use it to find their way back to the nest.
     * Some ants are equipped with mandibles called trap-jaws. This
       snap-jaw mechanism, or catapult mechanism, is possible because
       energy is stored in the large closing muscles. The blow is
       incredibly fast, about 0.5 ms in the genus Mystrium. Before the
       strike, the mandibles open wide and are locked in the open position
       by the labrum, which functions as a latch. The attack is triggered
       by stimulation of sensory hairs at the side of the mandibles. The
       mandibles are also able to function as a tool for more finely
       adjusted tasks. Two similar groups are Odontomachus and Dacetini -
       examples of convergent evolution.
     * Australian green ants are eaten by the aboriginals. Their abdomens
       taste like lemon sherbet, are high in vitamin C and have antibiotic
       properties. Squashed green ants mashed in water makes up an
       excellent lemon-lime flavored drink. The Amazon is also said to
       have lemon ants.
     * The Australian bulldog ant Myrmecia pilosula has only a single pair
       of chromosomes. Males have just one chromosome since they, like all
       male Hymenopterans, are haploid. The Australian bulldog ants are
       also among the biggest and most primitive. Each individual hunts
       alone, using its large eyes instead of their chemical senses to
       find prey. Like all ants they are social, but their social
       behaviour is poorly developed compared to more advanced species.
     * Scientists recently discovered that Polyrhachis sokolova, a species
       of ant, can swim and live underwater.

   Termites, sometimes called "white ants," are in fact not closely
   related to ants, though they have a somewhat similar social structure.
   They comprise the order Isoptera and are related to the cockroach.

Relationships between ants and other species

   An ant collects honeydew from an aphid
   Enlarge
   An ant collects honeydew from an aphid
     * Aphids secrete a sweet liquid called honeydew. Normally this is
       allowed to fall to the ground, but around ants it is kept for them
       to collect. The ants in turn keep predators away and will move the
       aphids around to better feeding locations. Upon migrating to a new
       area, many colonies will take new aphids with them, to ensure that
       they have a supply of honeydew in the new area. Ants also tend
       mealybugs to harvest their honeydew. Mealybugs can become a serious
       pest of pineapple if ants are present to protect mealybugs from
       natural enemies (Jahn and Beardsley 1994, 1996; Jahn et al. 2003).

   Camponotus compressus tending soft scales
   Enlarge
   Camponotus compressus tending soft scales
     * Myrmecophilous (ant-loving) caterpillars (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 are known to produce vibrations and
       sounds that are sensed by the ants. (DeVries, 1992)
     * Some myrmecophagous (ant-eating) caterpillars secrete a pheromone
       which makes the ants think that the caterpillar's larva is one of
       their own. The larva will then be taken into the ants' nest where
       it can feed on the ant larvae.
     * Allomerus decemarticulatus has developed a tripartite association
       with their host plant and a fungus in order to ambush their prey.
     * Fungus-growing ants that make up the tribe attini, including
       Leafcutter ants, actively cultivate certain species of fungus in
       the Leucoagaricus or Leucocoprinus genera of the Agaricaceae
       family. In this ant-fungus mutualism, both species depend on each
       other for survival.
     * Lemon Ants make Devil's gardens by killing all surrounding plants
       besides lemon ant trees.
     * Many trees have extra floral nectaries that provide food for ants
       and the ants in turn protect the plant from herbivorous insects.
       Some species like the bullhorn acacia ( Acacia cornigera) in
       Central America have hollow thorns that serve to house colonies of
       stinging ants ( Pseudomyrmex ferruginea) that defend the tree
       against insects, browsing mammals, and epiphytic vines. In return,
       the ants obtain food from protein-lipid Beltian bodies. Another
       example of this type of ectosymbiosis comes from the Macaranga tree
       which have stems adapted to house colonies of Crematogaster ants.
     * The peony plant is visited by ants, who can help the plant open its
       flowers.

   A Lycaenid larva and an ant
   Enlarge
   A Lycaenid larva and an ant

Humans and ants

   Ants are useful for clearing out insect pests and aerating the soil. On
   the other hand, they can become annoyances when they invade homes,
   yards, gardens and fields. Carpenter ants damage wood by hollowing it
   out for nesting. Nests may be destroyed by tracing the ants' trails
   back to the nest, then pouring boiling water into it to kill the queen.
   (Killing individual ants is less than effective due to the secretion of
   pheromones mentioned above). Many scales and homopteran species that
   are considered as horticultural pests are controlled by the use of
   grease rings on the trunks of the trees. These rings cut off the routes
   for ants and make the pest species vulnerable to parasites and
   predators.

   In some parts of the world large ants have been used as sutures by
   pressing the wound together and applying ants along it. The ant in
   defensive attitude seizes the edges in its mandibles and locks in
   place. The body is then cut off and the mandibles can remain in place
   for up to three days closing the wound.

   Some species, called killer ants, have a tendency to attack much larger
   animals during foraging or in defending their nests. Human attacks are
   rare, but the stings and bites can be quite painful and in large enough
   numbers can be disabling.

Ant control

   Modern society considers the ant a pest, and due to the adaptive nature
   of ant colonies, eliminating one is near impossible. Pest control with
   regard to ants is more a matter of controlling local populations than
   eliminating an entire colony. Attempts to control ant populations of
   any kind are temporary solutions.

   Typical ants that are classified as pests include Pavement Ants
   (otherwise known as the sugar ant), Pharaoh Ants, Carpenter Ants,
   Argentine Ants, and the Red Imported Fire Ant. Control of species
   populations are usually done with bait insecticides, which are either
   in the form of small granules, or as a sticky liquid that is gathered
   by the ants as food and then brought back to the nest where the poison
   is inadvertently spread to other members of the brood — a system that
   can severely reduce the numbers in a colony if used properly. Boric
   acid and borax are often used as insecticides that are relatively safe
   for humans. With the recent insurgence of the Red Imported Fire Ant, a
   tactic called broadcast baiting has been employed, by which the
   substance (usually a granule bait designed specifically for Fire Ants)
   is spread across a large area, such as a lawn, in order to control
   populations.

Ants as food

   Ants and their larvae are eaten in different parts of the world.

   In Mexico, ants' larvae, known locally as escamoles are considered a
   great delicacy in many restaurants.

   In the Colombian department of Santander Atta Sp. Colona ants are
   toasted alive and eaten. This tradition has come down from the native
   Guanes.

   In parts of Thailand, ants are prepared and eaten in various ways.
   Khorat ant eggs and diced flying ants are eaten as an appetizer. Weaver
   Ant Eggs and Larva as well as the ants themselves maybe used in a Thai
   Salad, Yum (ยำ), in a dish called Yum Khai Mod Daeng (ยำไข่มดแดง) or
   Red Ant Egg Salad, a dish that comes from the Issan or North-Eastern
   region of Thailand.It is said that the ants taste tart.

   In South Africa, ants are used to help harvest Rooibos, which is an
   otherwise difficult to cultivate tisane.

Ants in human culture

   Ants have often been used in fables and children's stories to represent
   industriousness and cooperative effort, as well as aggressiveness and
   vindictiveness. In parts of Africa, ants are the messengers of the
   gods. Ant bites are often said to have curative properties. Some Native
   American religions, such as Hopi mythology, recognize ants as the very
   first animals. Others use ant bites in initiation ceremonies as a test
   of endurance.

Gallery

   Weaver Ant Nest

   Leaf-cutting Ants (Atta sp. or Acromyrmex sp.)

   Electron Micrograph: Ant Head

   Ant Cultivating Aphids

   Ant Hill

   Ants Collecting Food

   Ant Trail

   Ant on Mosshill

   Fire Ant Carrying Food

   Sterile Female Worker
   Formica sp.

   Ant nest on bamboo tree.

   Weaving ants.

   Oecophylla a.k.a. weaver ants.

   Oecophylla a.k.a.weaver ant.

   Fire ants in water clustering together.

   Retrieved from " http://en.wikipedia.org/wiki/Ant"
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   with only minor checks and changes (see www.wikipedia.org for details
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