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ants, fourmis

Formicidae

What do they look like?

Ants are skinny insects. Like their relatives the wasps, they have a narrow connection between their abdomen and thorax. They have chewing mouthparts, and their antennae are bent in the middle. Some ant species are very tiny (1-2mm long), but some tropical species are very large (30 mm). Most species are 5-15 mm long. Some ant species can sting, and all can bite. Ants have lots of glands for producing chemicals. Most ant species are brown, but some are black, some are yellowish, and some are partly or entirely red.

Each ant colony has several different kinds of ants. They are all the same species, but they look different. Most of the ants you see are workers. They are female, but they cannot reproduce. They do all the work in the nest and protect it from enemies. Some ant species have different sizes of workers for different jobs: large ones with big jaws hunt or protect the nest, while smaller ones work inside, tending the young and digging. Inside the nest is the queen, she is a large female, and is the only one who can lay eggs. Some ant species have several queens in a nest, some have only one. At certain times in the summer there will be new queens and males in the nest as well. They have wings, and fly out to mate and start new nests. Males are usually smaller than females. Only males and queen ants have wings, but the queens remove their wings when they start a new nest. Worker ants never have wings.

  • Sexual Dimorphism
  • female larger

Where do they live?

Ants are very important insects all around the world, especially in tropical regions. There are over 11,000 species in the world, and at least 90 species in Michigan.

What kind of habitat do they need?

Ants are found just about every habitat on land except the very coldest. All ant species need sheltered places to nest and take care of their offspring. Most species nest underground, but some nest in trees. Some very small ant species can make nests inside acorns and other small hiding places.

Adult ants can live in drier conditions than many other invertebrates, but ant eggs and young need humid conditions to survive.

How do they grow?

Ants have complete metamorphosis. Queen ants lay eggs. The baby ant that hatches from the egg is a larva, with no legs, just a soft white body like a worm and a small head. The larvae are fed by the queen (in the first generation) and then by workers. The amount and kind of food an ant larva gets helps determine how big it will be as an adult, and whether it will be a worker or a queen. Each larva grows and molts, and eventually spins a small cocoon of silk, and inside the cocoon it transforms into a pupa. The pupa is a resting stage, it doesn't move or eat, but just completes the transformation into an adult ant. The new adult emerges from cocoon to join start working for the nest.

How do they reproduce?

Ants live in colonies where one or a few females, called queens, lay all the eggs. Most of the queens' offspring become worker ants that do not reproduce. A few are males, and some become new queens. Each queen ant can lay thousands of eggs per year.

  • How often does reproduction occur?
    In most species, queen ants only mate once in their life.
  • Breeding season
    Summer

When a new queen finds a good place for a nest, she builds a small chamber and lays some eggs. When the eggs hatch, she finds food, and feeds and takes care of them until they mature. They become workers, and they take over all the work in the nest. The queen does nothing but lay eggs.

How long do they live?

Queen ants can live for several years. Workers may live for a year but many only live for a few months. Males die as soon as they mate, so they only live for a few weeks. Sometimes a nest has several queens, and they can keep a large colony going for many years.

How do they behave?

Different ant species are active at outside the nest at different times of day. Many are active at night, some in the daylight. Workers are active inside the nest as long as it is warm enough: tending the young, expanding the nest, collecting food, disposing of waste, and protecting the nest from predators and parasites. Ants often carry food and water by swallowing it, and keeping it in a separate stomach, then regurgitating it to share with other nestmates. Ants use chemicals to work together. If their nest is attacked they produce alarm chemicals that cause other workers to come and help defend the nest.

How do they communicate with each other?

Ants can see, but not very well. They mainly communicate with scent and touch. They have complicated chemical signals that allow them to work together on different tasks. They often spread information by touching each other's antennae or head. Some ants also make noises by rubbing their legs against their body.

What do they eat?

Ant species eat many different foods. Some specialize in sugary liquids like nectar and the "honeydew" produced by aphids and other insects (see Aphids). Many eat other insects and other small animals, and scavenge dead meat. Some others specialize in eating seeds or fungus. Ants drink from dew, rain drops, and puddles, and sometimes they get their moisture from their food (like nectar).

Many ant species store food in their nests, especially the seed-eating ants. Others eat fungus that they grow in their nest. Ants that find a big food source leave a chemical trail, so that their nestmates can find the food too. Pretty soon there is a busy column of ants going back and forth from the nest to the food source.

Leaf-cutter ants live in warm climates, they cut up leaves and carry them into their nests underground. They eat the fungus that grows on the leaves. Army ants and driver ants roam through jungles and tropical habitats eating any animals they can find. They are big ants with sharp jaws, and there are many thousands of them in a group. They will eat any animals, even large ones, that they can catch.

What eats them and how do they avoid being eaten?

Worker ants attack predators, they will die to protect their nest. Some ant species can sting, and all can bite (though the little ones can't hurt a large animal). Many ants also have toxic chemicals they can spray on their enemies.

What roles do they have in the ecosystem?

Ants are very important in lots of roles. Some species disperse seeds, some are important predators of insects, some tropical species are important herbivores. Their digging often improves the soil for plant growth.

Species (or larger taxonomic groups) that are mutualists with this species
  • Aphids
  • Some caterpillars

Do they cause problems?

Ants can be major pests. Carpenter ants make their nests in wood, including houses, and several ant species come into houses looking for food. In the tropics leaf-cutter ants attack crops in the fields. Some stinging ants can be dangerous to people. Recently an ant species from South America was accidentally brought to the southern United States. It is called the Imported Fire Ant, and it makes large nests with thousands of stinging defenders.

  • Ways that these animals might be a problem for humans
  • injures humans
    • bites or stings
  • crop pest
  • household pest

How do they interact with us?

Ants are important predators of insects, including flies, caterpillars, and other pests.

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

Several ant species are considered threatened or in danger of extinction. This is because they live in special habitats that are very rare and may be destroyed by human construction or environmental change.

  • IUCN Red List [Link]
    Not Evaluated

Some more information...

In some parts of the world, including the United States, ant species have been accidentally brought in from other continents. These invader ants are causing a lot of problems.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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agricultural

living in landscapes dominated by human agriculture.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.

biodegradation

helps break down and decompose dead plants and/or animals

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chaparral

mid-altitude coastal areas with mild, rainy winters and long, dry summers. Dominant plant types are dense, evergreen shrubs.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

crepuscular

active at dawn and dusk

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

eusocial

the condition in which individuals in a group display each of the following three traits: cooperative care of young; some individuals in the group give up reproduction and specialize in care of young; overlap of at least two generations of life stages capable of contributing to colony labor

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

mycophage

an animal that mainly eats fungus

native range

the area in which the animal is naturally found, the region in which it is endemic.

nectarivore

an animal that mainly eats nectar from flowers

nocturnal

active during the night

nomadic

generally wanders from place to place, usually within a well-defined range.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Climbing plants are also abundant. There is plenty of moisture and rain, but may be somewhat seasonal.

scavenger

an animal that mainly eats dead animals

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

soil aeration

digs and breaks up soil so air and water can get in

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

taiga

this biome is characterized by large expanses of coniferous forest, there is an extended cold season and heavy snowfall.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland
savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland
tundra

A terrestrial biome found in very cold places -- either close to polar regions or high on mountains. Part of the soil stays frozen all year. Few kinds of plants grow here, and these are low mats or shrubs not trees. The growing season is short.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

year-round breeding

breeding takes place throughout the year

 
University of Michigan Museum of ZoologyNational Science Foundation

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. "Formicidae" (On-line), Animal Diversity Web. Accessed April 23, 2014 at http://www.biokids.umich.edu/accounts/Formicidae/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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