A social insect, characterized by a waist of 12 narrow segments, forming perennial colonies in nests made in wood, soil, plant cavities, or other constructions. The nest contains one or more fertile queens, many wingless, sterile workers, and winged males that fertilize queens during mass nuptial flights. Most ants scavenge animal remains; some are predators; others feed on fungi, seeds, or honeydew. (Order: Hymenoptera. Family: Formicidae, c.14 000 species.)
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Formica rufa worker |
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| Aenictinae Aenictogitoninae Aneuretinae Apomyrminae Cerapachyinae Dolichoderinae Dorylinae Ecitoninae Formicinae Leptanillinae Leptanilloidinae Myrmeciinae Myrmicinae Nothomyrmeciinae Ponerinae Pseudomyrmecinae |
Ants are one of the most successful groups of insects in the animal kingdom. 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.
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. 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. This species provides evidence of a link between modern ants and non-social wasps.
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).
Morphology
Ants are distinguished from other insects by the following traits: elbowed antennae;
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.
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. 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. Most queens and male ants have wings, which they drop after the nuptial flight;
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. 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. 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. 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.
Most of the common ant species breed in the same way. 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.
Communication and behavior
Ant communication is accomplished primarily through chemicals called pheromones.
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 behavior explains how ants adapt to changes in their environment.
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; 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. 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 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 behavior 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".
Locomotion
Ants usually lose, or never develop, their wings.
The more cooperative species of ants sometimes form chains to bridge gaps, whether that be over water, underground, or through spaces in arboreal paths.
Among their reproductive members, most species of ant do retain wings beyond their mating 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.
Ant cooperation and competition
Some species of ants are known for attacking and taking over the colonies of others ant species. Some ants, such as the Amazon Ants, are incapable of feeding themselves, but must rely on captured worker ants to care for them.
The tetramorium ant (Pavement ant) is famous for its urge to increase its territory.
Ants identify one another as friends through their scent, a hydrocarbon-laced secretion that coats their exoskeletons.
Types
There is a great diversity among ants and their behaviors.
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.
Of special note:
Bullet Ants (Genus Paraponera), located in Central and South America, are the most venomous insect. 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. 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. 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. 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. The ants grow the fungus because it produces special structures called gongylidia which are fed on by the ants. 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. Like all ants they are social, but their social behavior 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.
Relationships between ants and other species
Aphids secrete a sweet liquid called honeydew. 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. (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. 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. 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. Another example of this type of ectosymbiosis comes from the Macaranga tree which have stems adapted to house colonies of Crematogaster ants.Humans and ants
Ants are useful for clearing out insect pests and aerating the soil. 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.
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.
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. 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 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.
Gallery
Wikimedia Commons has media related to: Ant|
Weaver Ant Nest |
Leaf-cutting Ants (Atta sp. or Acromyrmex sp.) |
Electron Micrograph: Ant Head |
Ant Cultivating Aphids |
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Ant Hill |
Ants Collecting Food |
Ant Trail |
Ant on Mosshill |
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Fire Ant Carrying Food |
Sterile Female Worker |
Ant nest on bamboo tree. |
Weaving ants. |
Oecophylla a.k.a.weaver ant. |
Fire ants in water clustering together. |
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