Lee Kong Chian Natural History Museum

Formicidae

Photo credit: Wang Luan Keng
Kingdom:Animalia
Phylum/Division:Arthropoda
Class:Insecta
Order:Hymenoptera
Family:Formicidae

Description

Ants are familiar to most people and probably the most dominant insect group on earth, with an estimated 20,000 species. In Singapore, at least 280 species of ants have been recorded. Ants are found in almost every terrestrial habitat and individuals outnumber most other terrestrial animals. They are easily recognised, with three distinct body parts and a slender ‘waist’. This ‘waist’ (known as the petiole or pedicel) has one or two prominent swellings (nodes) that can be viewed without difficulty in profile. They differ from wasps in having distinct elbowed antennae. However, identification to species level is rather difficult. When threatened, most ants are capable of biting to defend themselves or delivering venom via a sting. The latter is restricted to the more primitive species and utilised for both defence and killing prey. A number of the more advanced species do not have a sting but use an acid spray which opens at the tip of the abdomen.

All ants are social insects and live in colonies in crevices, cavities, wood or in soil, organised into three castes: workers, queens and males. While workers are always wingless, young adults (sexual forms) are winged and perform nocturnal mating and dispersal flights. Typically the colony consists of one or more reproductive females and a large number of workers. Males are produced seasonally to fertilise the new virgin females. They are much smaller than the queens, winged and short-lived. After mating, the winged queens fly away, shed their wings and lay eggs in an enclosed cell or other cavity to start a new colony. The females do not eat during the development of the first brood; they sustain themselves and feed the brood on the degeneration products of their now-useless flight muscles and other energy reserves that are stored in the body. When the first brood of workers reach maturity, they break out of the cell and begin to forage and to feed the queen, which continues to lay eggs. From that moment onwards the workers take over all aspects of colony maintenance and brood care.

Most ants are predators or scavengers. Some ’farm’ aphids for their honeydew, harvest seeds, or raise fungi in underground gardens. The development of a large and distensible crop in worker ants allows them to collect honeydew and other sugary substances. These are regurgitated to feed other workers and larvae in the nest. Soldier ants defend the nest and workers. They are larger and possess a hardened head capsule as well as large jaws.

Ant nests can have several thousands to a million individuals Underground nests play a very important role in the ecosystem, aerating the soil, moving nutrients in the ground and removing dead plants and animals.

Ants can be grouped into three categories based on their chosen habitat: arboreal, epigeal, and subterranean. Arboreal ants are big-sized, with a diet largely comprising honeydew from homopterans and extra-floral nectaries or the special food bodies (Beccarian bodies) produced by some plants to attract ants. A large number of arboreal ant species have a mutualistic association with host plants.

Epigeal ants occur on the surface of the soil, nesting either under fallen logs or in the soil. They eat a wide variety of food that can be found on the forest floor, such as flowers, fruits and insects (dead or alive).

The last group of ants are subterranean-dwellers. They are usually small, foraging in soil and leaf litter. The nests are underground. They play an important ecological role through their tunnelling habits, ventilating the soil and allowing root penetration. The organic matter inside the nest also increases the nutrient level of the soil.

Several species are introduced and have caused considerable damage to the ecosystem.



Read more about the Hymenoptera order.
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