Think of yourself as a desert ant. You leave your nest to search for food early in the morning in the deserts of Tunisia, except you do not know where to find food. You, therefore, walk randomly in the desert in a circuitous outward path from your nest until you find food. If you would find food, how do you get it back to your home? How do you go back without having left for yourself any traces or signs in the wasteland, without knowing where you located, and most importantly, without ending up stranded in the scorching heat of the desert? Could you accomplish coming back each day with food? Well, desert ants can.

To find out how ants can do this, scientists observed their behavior, and surprisingly they have found that ants did not follow back on the same trail they randomly took after they left their nests. Instead, ants took a direct route as if they already knew where the nest exactly located. How do these ants find the closest way and shortest distance to their nest from their current locations? Former studies had found that red and forest ants secrete a chemical substance to mark their paths. They leave a trail of chemical scents or visual traces behind them—like leaving a trail of breadcrumbs to help you find your way home. However, the structure of desert sands and conditions are not consonant with containing chemicals that will carry an odor or leave visual cues. Even if such markings have made, it is hard to guarantee that they will remain intact long enough considering the harsh conditions of the desert. As in Hansel and Gretel fairy tale kids who could not return home for the breadcrumbs they had left on the trail eaten by birds. Therefore, these desert ants must be equipped with another cognitive mechanism so that they can return to their nests before succumbing to the midday heat.  

Black desert ants (Cataglyphis fortis) emerge from their nests in the heat of desert sand, which rises to 70 degrees with the rise of the morning sun, to search for the remains of other insects that were not as heat resistant as they are. They can only survive for one hour on the hot sand and under the blazing sun, which means that within an hour, they must find their food and bring it back home without getting lost. The journey is quite arduous and dangerous each day. If the slightest confusion occurs and they are not able to return to their nest in time, then it could cost them their lives.

Scientists conducted a series of research in the scorching deserts of Tunisia to find out how desert ants take their food to their nests in the shortest route possible. Researchers first determined an anthill and plotted the terrain around it to set up a coordinate plane. They observed that the ants left their nests very early in the morning to begin their daily search for food, and many of them eventually found grubs that had been planted by the scientists. However, researchers moved the ants to locations that they had not previously been to after the ant began carrying the food back to their nests. The attempt was to understand whether there was a “sign placement system” within the ants. This system would encourage the ant to find its last known location, in this instance where it had picked up, then find its way back home. However, the ant instead began heading directly to its nest. It was as if the ant determined its position concerning its nest and set off for it immediately. This experiment was repeated on many ants numerous times and with the same consistent results. The ants, as soon as they had placed on the ground, moved to the nest relative to there. With a wondrous intrinsic coding of some neurons in their nervous systems, they traveled the distance between their new location and the nest in the shortest way possible. In addition to this, the margin of error was very nominal; they found their nests with a ten percent error in the average distance of 500-meters and with an error of only two degrees in angle. Additionally, a fascinating discovery revealed that the ants could calculate errors in their navigation systems. As they approach their destination, they would make adjustments if they need to by moving back and forth in parallel lines to reach the nest with minimum error.

Scientists determined that desert ants have about a thousand lenses in their compound eyes (remember that a human eye has only one lens) and 80 lenses in each of their eyes that can detect polarized light that comes from different points in the sky. Polarized light occurs when sunlight enters the atmosphere of Earth, hits air molecules and other particles, and then scatters in all directions. This dispersion leads to polarization, and the light that starts to vibrate in many planes begins to vibrate in only one plane. Therefore, the strongest of them is a distinct polarization that always makes a 90-degree angle towards the sun. The lens system in the eyes of desert ants uses this polarization to form a kind of Sky Map. These ants will occasionally stop and robotically move their heads while returning to their nest. This brief period allows the ants to make this sky map by surveying the sky and making a mental note of its layout. Researchers believe that ants can then calculate the direction that they need to travel to return to their nest. They repeat this movement along the way to continually update their sky maps. If they cannot find their home, then they utilize a patterned search method with a set of circular motions. It means that each ant knows how far it is from their nest at every point of their journey.

Then, how do ants find their direction to the nest? Perhaps they were guided by the position of the sun in the sky is. To test this hypothesis, researchers placed a set of mirrors to make ants perceive the sun in a different state than where it ordinarily would be. It observed that the ants changed their directions according to the new state of the sun. However, this finding raised another question; researchers wondered how the time of day would affect the ants since the sun moves across the sky during the day. However, this finding raised another question; researchers wondered how the time of day would affect the ants since the sun moves across the sky during the day.

In another part of the experiment, the researchers caught the ants after they found the bait, closed a box over them, and kept them inside the box for several hours so that they could not see the sun and its movements. It expected that the ants would have trouble finding their way back after they were released since a long time had passed, and the sun was in a drastically different position in the sky. However, they once again returned home by using the shortest distance possible. It understood that the desert ants were aware that time was passing even though they could not see the sun.

We now understand that ants determine their direction home by using the sun, but we still do not know how they figure out the distance they must travel to return to their nest. Researchers have developed three hypotheses to explore this phenomenon. The first hypothesis was the energy hypothesis. According to this hypothesis, the ants were able to know how much energy they needed on the way back by calculating it they had spent until they reached their food. The depletion of their energy meant the end of their journey. An ant loaded with extra weights to test this hypothesis as soon as it reached its food. The scientists thought that if their body weight increased, then they would not be able to strike reach the nest since they would spend more energy on the return trip. However, in this case, it did not affect the ants, and they returned home in the shortest way possible regardless of their weight.

The second hypothesis was the optical-flow hypothesis. In this hypothesis, it believed that the ants had visual memory, and this was how they remembered the way back. To prove this, scientists prevented the ants from seeing their surroundings by blindfolding the ants when they found their food source. However, the blindfold did not prevent the ants from obtaining the shortest distance back home. As a follow-up to this experiment, the researchers placed an extensive television screen in front of the ants showing an endless desert on the television screen to make the ants feel as if they had crossed the entire desert in this simulation. They used various types of simulations, but the result did not change; the ants found their way.

The last test involved the pedometer hypothesis. It surmised that ants could be counting their steps to determine how far they had traveled. To test whether they were doing so, researchers attached stilts made of hair strands to the legs of one group of ants after they found the food. As their legs now extended, they could move with longer scale steps. Another group of ants had their legs cut below the knee, thus shortened to increase the number of steps needed to walk the required distance back. They then observed the return journey of both groups of ants. The results were astounding; the ants with shorter legs had concluded their course before reaching the nest, while the ants with longer legs ended up passing the nest. Thus, it understood that the ants counted their steps according to the distance they traveled.

The findings reveal that the ants are created with an internal system that keeps track of the steps they take and re-calibrates itself on the way back. People make these complex calculations with measuring instruments and by knowing the laws of trigonometry. However, these small creatures find their way directly back without using any tools or computer applications. They do not use their perception to find direction, and they do not use any other directional methods because they all remember direction and distance as they move forward. If you look at this situation, what would be your simplest explanation? You can only have one definition: These little creatures can measure distances and angles precisely by applying mathematical calculations and trigonometry within their conditions. Since the first day of their existence, these creatures show only a few of the shreds of evidence of the divine power created them out of nothing with wondrous systems and superior abilities in their bodies.

I have put my trust in God, my Lord, and your Lord. No living creature is there, but He holds it by its forelock and keeps it under His complete control. Undoubtedly, my Lord is on a straight path (He governs all that exists and carries out His decrees rightly and with absolute justice). (Surah Hud, 56)

Ants are highly social insects and have a complex system of internal communication. It is only by this system that the colonies manage to carry out their collaborative activities like nest- construction, food-gathering, brood-rearing, and defense of the colony. The fact that ants allow some alien species full access to the benefits of their society suggests that the guests must somehow have, in the words of Hölldobler, ‘broken the ant’s code, that is, attained the ability to ‘speak’ the ants’ language, which involves a diversity of visual, mechanical and chemical cues. ’

To support this suggestion, Hölldobler focused mainly on the rove beetle and looked into its communications and relations with certain species of ants. The relations vary considerably with the beetle species. Some live along the ants’ food gathering trail, some at the garbage dump, some in the chambers within the nest and others inside the brood chamber itself.

Atemeles pubicollis, a European species of beetle, is a well-known example of the species that live inside the brood chamber. It lives in the nest of the mound-making wood ant Formica polyetena during its larval stage. Hölldobler found that the ants’ adoption of the beetle larva depends on chemical communication. The larva secretes a substance that apparently acts as an attractant for the ant. The brood-keeping ants respond to the chemical signal with intense grooming of the larvae.

A different kind of communication takes place to elicit the ant’s feeding of the larvae. Hölldobler observed that the beetle larvae imitate certain begging behaviour of ant larvae involving mechanical stimulation of the brood- keeping adults. When the adult ant touches the beetle larva with its mouth or antenna, the larva rears up immediately and tries to make contact with the ant’s head. If the larva succeeds in tapping the ant’s lip with its own mouth, the ant regurgitates a droplet of food. The beetle larvae receive more food than the ant larvae since they perform the begging behaviour more intensely than the ant larvae do.

How does the ant colony manage to survive the beetle larvae’s competition for food? The answer is a simple:The beetle larvae are cannibalistic and unable to distinguish their fellow larvae from ant larvae by odour. Thus, they reduce their own population. That is why we find the ant larvae in clusters while the beetle larvae, having devoured their neighbours, are loners in the brood chamber.

The Atemeles beetles have two different homes with ants; one for the summer and one for winter. In the autumn, the beetles migrate to nests of the dark brown insect eating ants of the genus Myrmica. The reason for their migration is that brood-keeping and the food supply are maintained in Myrmica throughout the winter, whereas Formica ants suspend their raising of young. In the spring the beetles return to Formica nests for mating and the laying of eggs. The Lomechusa beetle are also co-dwellers with Formica ants. However, they do not change their environment for the winter. Instead, after hatching they simply move on to another Formica colony of the same species and share their food supply.

How the migrating beetle find its way to a Myrmica nest is another question. We find Formica nests normally in woodlands, whereas Myrmica are found in the grasslands beyond the woods. Hölldobler suggests that when the beetles leave the Formica nest, they generally move in the direction of increasing light. This may explain how the beetles manage to reach the relatively open grasslands where the Myrmica ants Jive. When they reach open grasslands they use the odour of the host species of ant to find a nest.

The beetle obtains recognition and adoption with a ritual, involving chemical communication, when it finds a Myrimica nest. The beetle first touches the ant lightly with its antenna and raises the tips of lts abdomen towards the host. The ant responds by secretions from glands on the tip of the abdomen. Next the ant is attracted to a series of glands along the sides of the beetle’s abdomen. Hölldobler calls these ‘the adoption glands’ because the ant will not welcome or adopt the beetle unless it senses their secretion. Most probably, the odour of this secretion mimics the odour of the ant can approach, and grasp it in order to carry it into the brood chamber.

The Atemeles care not the only species capable of making themselves at home with more than one kind of ant. Xenodusa beetles also change their nests with the seasons. The larvae live in Formica nests through the summer and live in the carpenter (Campotonus) ant nests in winter time. It is interesting that the carpenter ants also maintain larvae throughout the winter. Except for above mentioned beetles do not have the command of the ant language required to gain acceptance to the brood chamber. Some species of European beetles like Dinarda are limited to peripheral chambers of the nest of their host. Dinarda offers secretions from glands similar to Atemeles’ glands, but these secretions only induce the ant to tolerate the beetle, not to adopt it and take it into the brood chamber. Therefore Dinarda can only live on such food as it can find in the peripheral chambers. Other groups of beetles have communication sufficient only to allow the beetle to feed at the ants’ garbage dumps.

Many beetles closely resemble their ant hosts in appearance. This is particularly true of guests of the army ants. Some scientists concluded that the factor inducing the ants to accept the beetles as nest-mates was the beetles’ morphological resemblance to themselves. It was even thought to be case with Atemeles, although they do not particularly resemble their hosts. Hölldobler altered the shape ond the collar of these beetles artificially and found that morphological features do not contribute to the success of their relationship with their host. Instead it appears that communicative behaviour remains the essential requirement for acceptance. The guests’ mimicry of their hosts’ appearance, probably serves as a protection against predation by birds.

There are some questions still to be answered about ants and their hosts: How did the fascinating, effective system of communication between the beetles and their hosts develop?Why do only some species of beetles have this ability while the rest do not?

REFERENCES 

• ATKINS, M. D. (1980) Introduction la Insect Behaviour, Macmillan Publishing Co. Inc. , New York, pp. 100-2.
• HÖLLDOBLER, B. (1971) ‘Communication between Ants and their Hosts’, Scientific American, January, pp. 86-93.
• WIGGLESWORTH, V B. (1964) The Life of lnsects, The New American Library, New York