Ants run much of the terrestrial world as soil turners, channelers of energy, dominatrics of the insect fauna and yet receive only passing mention in textbooks on ecology.
They employ the most complex forms of chemical communication of any animals and their social organization provides an illuminating contrast to that of human beings, but not one biologist in a hundred can describe the life cycle of any species.
Ants are classified as a single family, the Formicidae, within the order Hymenoptera, which also includes the bees, wasps, sawflies, ichneumons (order of parasitic wasps whose larvae feed on other live insect larvae), and similar forms.
2. Incidental or adventitious ant-nest sites are associated by chance and are not an integral part of plants.
Such incidental nest sites can be divided into convenient categories as follows:
- Preformed cavities in live branches and stems, excavated by wood-boring beetles and other insects and then later occupied by ant colonies.
- Cavities in stems and branches that are naturally hollow or contain a pith soft enough to be easily excavated by ants which includes grasses, sedges, composites, and other herbaceous and shrubby plant forms and so a great variety of ants occupy them.
- Natural or preformed cavities in the bark of trees; such as, pine trees in the southern United States that shelter an entire fauna of ant genera that nest adventitiously in the bark.
- Roots of epiphytes or the tangled root systems of orchids, gesneriads (mostly tropical herbs or shrubs), and other tropical epiphytes are ideal nest sites for ants.
- Galls (abnormal swelling of plant tissue) formed by cynipid wasp larvae, or Cynipidae, a family of gall wasps, hymenopteran insects in the super-family Cynipoidea that produce galls on oaks, which have been observed in Europe and North America.
- Earthen or carton nests constructed vertically against the sunken portions of tree trunks by a few ant species in the New World tropics because the trees provide a partial wall of solid wood which provides some protection for the ant colonies.
None of these diverse structures appears to be "designed" to accommodate ant colonies and all of them are ordinary anatomical features of the plants that the ants exploit, apparently in a unilateral manner.
In contrast, the domatia do appear to serve as ant nests because they are featured by cavities that form independently of the ants.
So, it is adventitious when roots and tubercles absorb nutrients from waste material carried onto the cavities, and even holes or thin windows of tissue through which ants can more conveniently enter and leave their colonies are essentially provided naturally by the plants, but not to entice ants as with the domatia.
- The head
- The thorax or mid-section.
- The abdomen or gastor.
Three pairs of legs are attached to the thorax, and like all insects, their bodies are encased in a hard, shell-like covering or exoskeleton and their legs are jointed.
The thorax can be broken down into two major parts: the alitrunk which contains the legs and wings, and the petiole which is found directly anterior to the gastor and is found only in ants.
Ants have mandibles (jaws) which are of varied structures. These varied structures provide for a plethora of functions ranging from grasping, tearing, cutting and other special tasks.
Most ants have a stinger at the end of the gastor. Some ants can release this stinger similar to the way honeybees do it. The stinger is only found in female ants and is a modified ovipositor (egg laying organ).
Ants have compound eyes which have not been shown to effect their behavior, although some ants seem to be able to detect movements. They have very sensitive antennae that are used for a wide array of communication.
Nearly all ants have a unique gland found on the petiole called the metapleural gland. Most importantly, this gland has been shown to contain antibacterial and antifungal chemicals which are essential for survival in the humid, dark nests in the ground or rotting vegetation.
This gland secretes an antiseptic substance that at times acts as a repellent to attacking organisms. It is also thought that the metapleural gland releases pheromones for communication.
Their varied mandibles are an irreplaceable tool for accomplishing the jobs necessary for the multiple behaviors displayed by various individuals of colonies.
The metapleural gland excretes antifungal and antibacterial materials that ants spread throughout their colonies through their wanderings. This protects their brood and their food supplies in the humid underground environment.
After selecting a nest site, a queen will begin laying eggs and caring for her brood. The first workers that develop assume brood care, leaving the queen to simply lay eggs.
Ant colonies can have single or multiple queens. The number of queens in multiple queen colonies varies by species, ranging from a few queens to nearly half the population in a colony.
Depending on the ant species, queens may live from months to years.2. Males, that serve one purpose which is to mate or breed with the queen.
Males typically die soon after mating or are forced to leave the colony and are normally alive solely during the colony's reproductive stage or period.3. Workers, which are sterile, wingless females that form the main members of the colony.
They perform the tasks necessary for the survival and growth of the colony; such as, foraging for or finding food, caring for the brood (eggs, larvae, plus the queen), and excavating or enlarging the nest.
Epiphytes are plants: such as, a tropical orchid or a staghorn fern, that grows on another plant upon which it depends for mechanical support but not for nutrients. They are also called aerophytes or "air plants".
One of the most complex mutualisms between plants and ants is the ant garden
To qualify as a true ant garden, the plants must benefit from the ant associations which is an aggregate of epipytes assembled by ants.
The ants bring the seeds of the epiphytes into their carton nests and as the plants grow, nourished by the carton and detritus brought by the ants, their roots become part of the framework of the ant nests.
The ants also feed on the fruit pulp, the elaiosomes (food bodies) of the seeds, and the secretions of the extra-floral nectaries.
- Monomorphic, all the same size.
- Dimorphic, of two sizes.
- Polymorphic, more than two sizes.
Workers divide labor, so some leave the nest to find food while most of them stay in the nest to take care of all of the other tasks which need to be done.
In other words, the nest site is changed at relatively frequent intervals, in some cases daily, and the workers forage in groups.
An ant is said to be a small insect that’s always busy; yet, always finds time to go on picnics with everyone's aunt.
Six labial and six maxillary muscles with different functions control the several joints and ensure the proper performance of the labiomaxillary complex.
Since glossa protractor muscles are absent, the protraction of the glossa, the distal end of the labium, is a nonmuscular movement.
Do ants really have tongues? They don’t have anything that looks like a vertebrate tongue, but they definitely have a structure that functions in the same manner.
The tongue structures of an ant are fairly complex, because an ant mouth has many functions to perform:
- groom themselves
- socially groom others, including the larvae
- determine food quality
- manipulate food
- ingest food
- give food to others via trophallaxis (mutual exchange of regurgitated food nutriments or other secretions that occurs between adults and larvae of certain social insects; such as, ants)
- beg for food from others
An ant mouth has many utensils and parts. There are brushes made of setae (stiff hair, or bristle); papillae (small protuberances on the tongue) for tasting; thin finger-like palps (segmented appendages usually found near the mouth in invertebrate organisms; such as, insects, the functions of which include sensation, locomotion, and feeding) for tasting, begging and manipulating; and various grooves and filters for moving and processing food.
The blade-like mandibles surrounding the mouth are for cutting, carrying, and in some species, catching prey.
Because of unusually low levels of intraspecific aggression, the Argentine ant can establish extremely large colonies.
This contributes to its status as a nuisance pest in homes and its ability to spread rapidly. Other negative effects of this invader include facilitation of plant feeding pest insects (for example, honeydew producing insects) and disruption of native ants, pollinators, and even vertebrates.
The Argentine ant, Linepithema humile, is among the world's most successful invasive species.
This ant has become a cosmopolitan pest, particularly in the Mediterranean climates of North America, Chile, South Africa, Australia, and southern Europe.
They have been very successful in spreading over great geographical areas, in part, because different nests of the introduced Argentine ants seldom attack or compete with each other, unlike most other species of ant.
In their invading ranges, their genetic makeup is so uniform that individuals from one nest can mingle in a neighboring nest without being attacked; so, in most of their introduced ranges they form "supercolonies".
Such ants have a social organization, called unicoloniality, allowing individuals to mix freely among physically separated nests.
These introduced Argentine ants are renowned for forming large colonies, and for becoming a significant pest, attacking native animals and crops.
In Europe, one vast colony of Argentine ants is thought to stretch for 6,000 km (3,700 miles) along the Mediterranean coast, while another in the U.S., known as the "Californian large", extends over 900 km (560 miles) along the coast of California. A third huge colony exists on the west coast of Japan.
While ants are usually highly territorial, those living within each super-colony are tolerant of each other, even if they live tens or hundreds of kilometers apart. Each super-colony, however, was thought to be quite distinct; however, it now appears that billions of Argentine ants around the world all actually belong to one single global mega-colony.
During research with these ants from different geographic areas, whenever the main European and Californian super-colonies and those from the largest colony in Japan came into contact, they acted as if they were old friends when they were observed rubbing their antennae with one another and never became aggressive or tried to avoid each other.
In other words, they acted as if they all belonged to one vast colony, despite living on different continents separated by vast oceans.