Ants, the cousins of honeybees, are workaholic as they are busy working day and night. Addicted to work and having never-say-die spirit, make them excellent foragers which work round the clock, apparently without any rest.
Ants have the highest developed social system, next only to man, with no apparent conflict seen in the society. A colony may have few thousand to over 500,000 individuals. The nests are built in various designs and are called Formicaria. Extreme devotion to duty and “Work is worship” attitude binds them together.
Like honeybees, they have polyethism, which means castes are specialized to carry out specialized duties in the colony. For example, the queen has large abdomen to lay a lot of eggs (2-3 million in a year), males fertilize her, workers have broad, sharp mandibles for cutting and chewing and the soldiers have large head that bears sharp dagger-like mandibles for fighting.
Workers and soldiers are sterile females. Soldiers of the door-keeping ant (Colobopsis etiolata) have such gigantic heads that they use it for blocking the entrance of the nest. They are extremely powerful creatures that can easily lift 20 times their own weight.
Ants have poor eyesight and are deaf but have a highly sophisticated chemical language for communication. They possess glands that secrete pheromones or messengers of chemical language that is perceived by one of antennae or feelers located on head. The mutual attraction among the members of a colony is maintained by endless antennal caressing, licking and nuzzling during which they trade food, glandular secretions and enzymes, which is called tropholaxis.
The course of migrating ant columns is directed by the chemical trail left by the scouts and constant body contacts among the following foragers. Sometimes if their chemical trail is washed away by rain, they are doomed to follow each other’s trail in circular tracks with eccentrically high speed.
Most species excavate nests in the ground or wood but some construct suspended nests on trees made of earth, carton, was or silk, while some, like safari ants, do not build nests at all. Desert ants build crater-like nests or mounds in which they are able to maintain temperature much below the outside heat. They even decorate their nests with pebbles, twigs and pine needles or body parts or dead insects.
In some species stones are used to close the entrance before rain or storm. Soldiers of doorkeeper ants (Colobopsis etiolata) possess excessively enlarged head which is used to block the entrance of nest to prevent the entry of predators. However, workers of the colony are allowed entry after they gently tap on the head of doorkeeper soldier. The tropical ant Oecophylla makes nest by webbing the leaves with silken thread that is produced by their larvae. While many workers hold the leaves close together, some workers hold the larvae in their mandibles and use them like living thread balls to spin web to attach the leaves together.
FORAGING & STORAGE
A vast majority of ants are omnivorous and eat insects, small animals, seeds, fungus etc. More than 75% of workers are out for food gathering at any one time. Scouts are sent out for searching in more or less in straight path. The information is passed on to the other workers through chemical language. They leave a trail of pheromone from the food source to the nest which other workers follow. They store surplus food in special chambers called granaries for the lean period. Wet seeds are first dried by spreading them in the sun and the radical of each seed is carefully bitten off to prevent germination during storage. Liquid food is brought in the stomach and regurgitated in the nest and fed to the queen brood and other members.
Almost all ants store food for the lean periods but in the Australian honey pot ants (Myrmecocystus hortideorum and Camponotus inflatus), also called honey barrels, some members are specially modified to store honey. Their bodies are sac-like and appendages modified as hooks. They store honey in their enormously large abdomen and hang from the ceiling and perform no other apparent function. These casts are called Repletes which are specially adapted to store honey stolen by foragers from the bee hives. The abdomen of repletes when full of honey, swells like a balloon making them incapable of locomotion. These live storage tanks hang from the ceiling and regurgitate honey whenever required by the community.
SWARMING AND HUNTING
Some of the primitive species of ants are hunters; famous among them are the legendary Safari ants or Driver ants of Africa and South America that belong to the family Dorylidae, which were first described by David Livingston in 1853. They are ferocious ants armed with sharp sickle-like mandibles that act like a pair of scissors and also have a weak sting. They are vagabonds moving in large columns of about half a kilometre, with a density of 13 ants per square centimetres. As they move searching every tree, branch and rock of the forest, fear grips the whole area as they attack every animal on their way, covering their bodies in millions and removing chunks of flesh, leaving their skeleton behind within minutes. Even larger animals like monkeys, pythons and deer are demolished by sharp jaws and sheer numbers.
Dairy ants such as Camponotus compressus domesticate aphids called ‘Ant cows’ since they relish their sugary secretion called ‘honey dew’. They keep them in their nests, bring them out in daytime for grazing and protect them from predators. Milking is done by stroking the aphid with antennae so as to stimulate it to eject a drop of honey-dew which antes greedily collect. The common yellow ant stores hibernating eggs of such aphids in their nests and protect them all the winter with amazing foresight. In the nest spring eggs are brought out and placed on their host plants for hatching. Some species of root feeding aphids are domesticated within nest chambers where they suck the sap of plant roots traversing the ant nests and yield honey dew regularly.
Leaf cutting ants, fungus growers and gardening ants have taken to elaborate agriculturing to obtain a steady and sure supply of food. The leaf-cutting ant (Atta) cuts pieces of leaves and carries them inside their nests to serve as compost, on which they grow fungus gardens. Farmer ants (Holcomermyx) cultivate choicest grasses outside their nests in well-prepared and manured fields. These crops are protected from pests, de-weeded and harvested, and their seeds stored for the next season.
WARS AND SLAVERY
The blood red slave-making ant, Formica sanguinea, described by the renowned entomologists, A.D. Imms and E.O. Wilson seems to have specialized in fighting wars and making slaves from other species of ants, like Formica subsericea. Two species found in South America, namely, Formica subintegra and F. sanguinea organize raids on other colonies to rob them of their food reserves.
Planning of a raid takes several days based on the information gathered by their spies. Inspection of the victim’s colony is done carefully and attack from several directions is normally carried out, giving an element of surprise to the opponent. Propaganda pheromones are released from dufour glands to confuse and demoralize the opponent. The attacked colony is mostly defeated and their granaries robbed. The adults are usually killed but the young larvae are brought to the nest so that they can grow to become slaves and can be used to do menial household jobs.
Close observations on ants reveal a highly developed social system and some of their activities resemble our own, exhibiting a high degree of intelligence. Although they practice a well-marked caste system, there is never a conflict in their society, which is perhaps due to their strong sense of duty.