Ants. Can’t live with them, can’t live without them. They’ve been around for ages and outnumber us by over a million to one. They’re not just home invaders and picnic crashers; they’re the only other animal known to have sophisticated agriculture and manage herds of livestock. With more than ten thousand species to choose from, there’s an ant for every occasion. Did you rip your favorite shirt? Make friends with some weaver ants. Are you looking for someone to mow your lawn? Hire an army of grass cutter ants. Is life dull and you just want a thrill? Try bothering a stampede of African driver ants and get the adrenaline rush of a lifetime. I’ve mentioned ants before, but now is their time to have the spotlight.

   I couldn’t possibly cover every ant I would like to in this article, but I did manage to choose a select few, starting with the infamous bullet ant (Paraponera clavata). This ant is well known to have the most painful known insect sting in the world. As its name infers, the sting is likened to having a bullet wound. Justin Schmidt, a dedicated and somewhat eccentric entomologist, has painstakingly (pun intended) stung himself with as many insects as possible to compile the Schmidt Sting Pain Index. The pain of various insect stings, which he describes in wildly imaginative detail, are ranked from 1 to 4 (with 4 being the most painful). Can you guess who won that coveted number 4 on the scale? Take a moment. I’ll wait. Okay, now that you’ve guessed I can confidently assume that you thought about the bullet ant. After all, it is the star of this section. If you did choose the bullet ant, you’re wrong. That honor actually goes to the tarantula hawk wasp. No, the bullet ant doesn’t play by the rules. It has a sting so awful that it got its very own ranking of 4 plus. Not even the scale could contain the pain. As with many other animal toxins, bullet ant stings affect voltage gated sodium channels on cell membranes. This can wreak havoc on a cell’s ability to transmit signals, especially in the central nervous system (CNS). The blocked signals in nociceptors and skeletal muscles are what leads to the intense pain, paralysis, uncontrollable shaking, nausea, and more. The legendary sting of P. clavata is the reason it has become the gatekeeper of boys on their way to becoming warriors. The Sateré-Mawé tribe of Brazil has used this ant for years as part of a culturally important initiation rite. One sting is more than enough to cope with, but Mawé boys must endure multiple stings. Bullet ants are collected and dipped into a natural sedative to be safely woven into large gloves made from palm leaves. At the start of the initiation, a young man must slip both his hands into gloves filled with, now irate, immobilized ants. Only a thin layer of charcoal protects his hands and he must wear these gloves for five minutes straight and take the pain. What’s worse is the effects of the venom last well beyond these five excruciating minutes and boys hoping to become warriors must undergo this nightmare a total of twenty times before they are fully initiated. Forget jaguars, caimans, and anacondas. The Mawé people consider this humble ant to be the worst their rainforest home has to offer.

    Despite the potency of the venom delivered by the ant itself, one component may have medical significance. This compound of P. clavata, known as poneratoxin (PoTX), can have an analgesic effect in rats if administered in a small, controlled amount. Not only that, but it could potentially serve as a biological insecticide thanks to its ability to block transmission in the insect CNS.

   Now it’s time for an ant that poses no threat to people, but is an amazing survivor. Meet the Saharan silver ant (Cataglyphis bombycina). This ant is capable of surviving conditions that would cook virtually any other living creature. In the Sahara desert, the surface of the sand can reach temperatures of up to 158℉ under the brutal midday sun. Several ingenious evolutionary adaptations give C. bombycina the ability to cope with this unforgiving environment while all others must either hide or perish. One strategy is to limit the time of exposure. Even these hardy ants will die if they are out on the scorching sands for long enough. That’s why they turn their foraging trips into a mad dash for their lives. Groups of ants leave their nest in a frantic search for other arthropods, such as desert beetles, that were too slow to escape the sun’s deadly rays. Once located, prey is dragged back to the nest as fast as possible via extraordinary teamwork. The poor animals that die and end up providing for these ants have succumbed to what is known as heat shock. Every living organism produces substances called heat shock proteins (HSPs). HSPs are tied to specific genes (heat shock genes) that, when activated by high temperature, are expressed and direct synthesis of HSPs by the cells. The purpose of these proteins is to protect the body from severe heat shock. Normally they are not produced until there is an environmental trigger, but Saharan silver ants start to produce them before leaving their nests. HSPs are synthesized preemptively to give the ants protection so they don’t die upon exiting their nest. This is because their foraging trips are usually too short to trigger synthesis of HSPs the normal way and the temperature rise would kill them before they got the chance. Not only are these HSPs produced before exposure, they continue to be synthesized beyond temperatures that would kill other animals, giving silver ants an even greater edge.

   Another advantage over everyone else is long legs and a fast gate. Even though the sand itself may reach temperatures past what C. bobmbycina can tolerate, it is significantly cooler just a few millimeters off the surface. The long, stilt-like legs of this ant raise it off the sand just enough to keep its body below its critical maximum of 128.5℉. Long legs generally mean an animal can run faster, and C. bombycina is no exception. Its gait is a frenzied sprint that, at top speed, becomes quadrupedal. That’s right, these ants will actually lift their front legs off the ground completely to pelt forward as quickly as they can, and to minimize exposure to the sand. Running fast and limiting each foot’s contact with the ground allows them to go farther and keep cooler in their short bursts of foraging. They use the sun to navigate so that they can keep track of where they are in relation to their nest and how long they have been out.

   Unfortunately, special proteins, great legs, and excellent navigational ability aren’t enough to beat the heat. Silver ants actually spend the majority of their scavenging forays offloading heat while sitting atop dry vegetation or stones. What allows them to do this so efficiently is the hair that gives them their name. These gleaming, silvery coats are what put them above and beyond everyone else when it comes to desert survival. Each individual hair is a triangular shape with two ridged surfaces and one smooth surface. The smooth surface sits against the body and the ridged surfaces face outward. When solar radiation hits the surfaces of these hairs, the ridges trap it and scatter that radiation back out in all directions. This is called “Mie scattering” and enhances the hairs’ reflectivity in the visible and near infrared range where solar radiation is at its strongest. In the mid infrared, the silvery hairs become antireflective and help the ants offload heat through emissivity. But what about the heat radiating off the ground? C. bombycina is prepared for that too. The undersides of their bodies are bare and reflect the mid infrared radiation from the sand better than if they were covered in hairs. All of these features, and more, combine to optimize survival and allow silver ants to be the lean, mean, foraging machines that they are.

   There are countless ways to protect yourself from all kinds of threats if you’re an ant. Wearing what is essentially a heat shield or having a sting that will cripple your attacker with pain are just two. How about being heavily armored and using your head as a door to seal everyone out of your house? Using your own body as a barrier is called phragmosis and it’s what several genera of ants choose to do. Ants, as colonial animals, all have specific jobs to help their family. For ants in these phragmotic genera, usually the soldiers, that job is protecting the nest with their heads when the colony is threatened. The head structures, or cranial discs, that aid this can come in a variety of shapes and sizes that match their purpose. Some are even covered with sticky, fibrous secretions that accumulate environmental debris to help escape detection (cryptic phragmosis). Not only can they be used for blocking entrances, they can also be used like bulldozers to physically push intruders out of the nest. In one species of ant, Blepharidatta conops, it is the queen who possesses a head disc that she uses to block her nest chamber. The diameter is much too small to be of use blocking the nest entrance, but it certainly gets the job done when it comes to protecting her young. Perhaps one of the most diverse phragmotic genera is Cephalotes, also called turtle ants. In Cephalotes, generally all castes from workers to queens possess some kind of highly adapted head shield. These arboreal ants dwell high in the canopies of neotropical forests and use their heads to plug the holes of their wood cavity nests. They are also capable of gliding down from the canopy using what is known as Directed Aerial Descent, which is pretty cool. These ants are basically weird insect superheroes. Anyway, the morphology of the cranial discs prevents exposure of eyes, antennae, and mandibles to predators, just leaving them with a perfectly fitted, armored door to deal with. As mentioned before, these discs can be covered in organic material that sticks to glandular secretions, making entrances hard to locate in the first place.

   In a fantastic example of convergent evolution, there is a genus of Old World ant, Carebara, that has independently developed a very similar head shape to that seen in Cephalotes. The convex, shield-like head disc shape may have evolved independently even among separate species of Carebara. As ground nesting ants found in the leaf litter of African forests, Carebara workers have cephalic discs that collect soil and other debris, thereby camouflaging the nest entrances. They do not possess the sticky secretions of Cephalotes, but litter and soil easily collect on small hairs. When threatened by an intruder, they lock their heads down, making them both harder to see and the nest more difficult to invade.

   Reverse phragmosis has also been hypothesized, but as of now not proven, in the queens of the species Pheidole embolopyx. This is when the ant has a truncated (shortened), shield-like abdomen. So basically it’s a butt door. Or it would be if it was used to block nest tunnels. In the numerous experiments performed by E.O. Wilson and B. Hölldobler, not once did the study queen use her abdomen defensively. She always went on the attack, using her mandibles to nip at any threat they presented her with. She even turned completely around in her tunnel to attack the dissecting needle approaching her from behind rather than using her abdomen as a shield. It’s still a mystery what purpose this flat and potentially phragmotic abdomen serves. However, it does really reinforce the saying “Don’t judge a book by its cover.”

   That goes for any of the ants in this article or anywhere in the world. Ants have a bad reputation and we’re all too quick to judge them and make assumptions based on the bad experiences we’ve had with a handful of species. In reality, there are trillions more ants out there that are just going about their own business, often in a truly fascinating manner, and want nothing to do with us. Let’s appreciate and think about those ants before we go judging any ant we see.

The wonderful Justin O. Schmidt sadly left us in February of 2023. He was an invaluable and pioneering contributor to the scientific community and will be dearly missed.

References:

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7. Gough, Zoe. “The World’s Most Painful Insect Sting.” BBC Earth, BBC, 13 Mar. 2015, www.bbc.com/earth/story/20150312-the-worlds-most-painful-insect-sting.

8. Gehring, Walter J., and Rüdiger Wehner. “Heat Shock Protein Synthesis and Thermotolerance in Cataglyphis, an Ant from the Sahara Desert.” Proceedings of the National Academy of Sciences, vol. 92, no. 7, 28 Mar. 1995, pp. 2994–2998., doi:10.1073/pnas.92.7.2994.

9. Zollikofer, Christoph P. E. “Stepping Patterns in Ants II. Influence of Body Morphology.” Journal of Experimental Biology, vol. 192, no. 1, 15 July 1994, pp. 107–118.

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11. Alonso, José Ramón. “Flat Heads.” Mapping Ignorance, Dinahosting, 8 Jan. 2016, mappingignorance.org/2016/01/08/flat-heads/.

12. Brandão, C. R. F., et al. “The First Case of Intranidal Phragmosis in Ants. The Ergatoid Queen of Blepharidatta Conops (Formicidae, Myrmicinae) Blocks the Entrance of the Brood Chamber.” Insectes Sociaux, vol. 48, no. 3, Sept. 2001, pp. 251–258., doi:10.1007/pl00001774.

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Photo and Video Links:

1. Guarding the empire’s treasure by Peter Steward

2. Paraponera clavata by Graham Wise

3. https://www.youtube.com/watch?v=VbkgNDERlpU

4. Texas Turtle Ant, solider (Formicidae, Cephalotes texanus) by Alejandro Santillana

5. Figure 1

6. https://www.chemistryworld.com/careers/the-man-who-gets-stung-by-insects/2500173.article