Communication and behaviour
Ant communication is primarily through chemicals called pheromones, which, because most ants spend their time in direct contact with the ground, are more developed than in other Hymenopterans. So, for instance, when a forager finds food on her way home (found typically through remembered landmarks and the position of the sun), she will leave a trail along the ground, which in a short time other ants will follow. When they return home they will reinforce the trail, bringing other ants, until the food is exhausted, after which the trail is not reinforced and so slowly dissipates. A crushed ant will emit an alarm pheromone that in high concentration sends other ants nearby into an attack frenzy, and in lower concentration attracts them, while a few ants use what are called propaganda pheromones to confuse their enemies. And so forth.
Like other insects, ants smell with their antennae. These are fairly mobile, having as mentioned above a distinct elbow joint after an elongated first segment, and since they come in pairs provide information about direction as well as intensity. Pheromones are also exchanged as compounds mixed in with the food interchanged 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) each other belongs to. Of special note, the queen produces a special pheromone without which the workers will begin raising new queens.
Ants attack and defend themselves by biting, and in many species, stinging, in both cases sometimes injecting chemicals into the target. Of special note here is formic acid.
Types
There is a great diversity among ants and their behaviors.
See list of ant genera (alphabetical) for an alphabetical compendium of wordwide ant genera.
Of special note:
- 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 nest 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.
Humans and ants
Human beings have had a mixed relationship with ants through most of history. They can also be important for clearing out insect pests and aerating the soil. On the other hand, they can become minor annoyances or major pests themselves 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 secrietion of pheremones mentioned above).
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. These can be especially problematic when introduced into areas where they are not native.
Ants have often been used in fables and children's stories to represent industriousness and cooperative effort, as well as aggressiveness and vindictiveness, and ants are sometimes used as a cure for laziness (such as in Morocco). 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 first people. Others use ant bites in initiation ceremonies as a test of endurance.
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.
See also
External links
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