When I think back on my childhood as a young biologist, a few memories pop up that point to my inevitable career as an entomologist (insect researcher) and parasite/pathologist (more on that later). One of these memories is of me and my dad sitting on the bathroom floor in my childhood home and watching a line of sugar ants (Tapinoma sessile) march out of a previously unknown minute hole in our wall. I remember being fascinated by how well-organized and steadfast these little creatures were in their mission to find and steal our sugary treats. I wanted to know how these chaotic-looking insects could perform such complex tasks. Fortunately, as I advanced through my biology studies, I had the opportunity to work with a few myrmecologists (ant researchers) who opened my eyes to the wonders and intricacies of these tiny organisms. Now, I wish to share some of what I learned about these incredible insects with all of you. So grab your hydrocortisone (anti-itch) cream and enjoy the wonderful world of ants.
What are ants?
Ants are insects, and like all insects, they possess a hard exoskeleton made of chitin, six legs, a three-part body plan, and antennae. Genetically, they are closely related to wasps, bees, and sawflies, a group known as the hymenopterans. Without getting too technical, most hymenopterans typically have two sets of wings, flexible abdomens, mandibles, and a specialized structure called an ovipositor used to lay eggs, sting, or cut. As with everything in biology, these characteristics are not all-encompassing. But as a good rule of thumb, if you see an insect that resembles a wasp or ant, it is probably a hymenopteran.
What sets ants and other hymenopterans apart is their social structures. Unlike bees and wasps that can either live solitary or colony-forming, ants exclusively form colonies. These colonies have extraordinarily complex social structures in which individuals develop into different forms or castes. You may recall the term “caste system” from your history classes in which people are born into strict social groups that are allowed to perform different roles or live certain lifestyles. Ants follow almost a similar system but without racism and classism.
A colony starts with a queen that, following her mating flight, searches for a safe spot to lay eggs. Once she finds the perfect home, she lays eggs that eventually develop into female workers. Some workers care for unhatched eggs, while others forage for food. As the colony grows, workers can develop into more specialized castes that look dramatically different from each other. Eventually, the colony will reach the reproductive stage and produce princesses and males (called drones) for mating. These reproductive castes are responsible for starting new colonies. Because individual ants entirely rely on colonies to survive, we refer to ant colonies as superorganisms.
What do they do?
You may be used to seeing ants around your garden or in your home. If you were to observe them, you would probably see a few carrying things heavier than themselves, others fighting with insects, or even some invading your home to search for food. It is hard to imagine how ants influence the environment around them in any positive light when they only seem concerned with advancing their colony. However, ants have a profound effect on the environments around them.
One of the many things ants are associated with is elaborate tunnel systems. Many ant species dig tunnels through soil to construct their nests. The primary purpose of these tunnels is to provide a safe home for the ants, but they can also benefit other organisms. When ants dig large nests, they alter the soil. They change what nutrients are available in the soil, the soil’s pH, and even the structure of the soil itself (compact to less compact). These alterations make the soil more accessible for the establishment of other organisms, such as fungi and arthropods. Even after the colony dies, the changes they make to the soil persist. Like beavers who build dams or woodpeckers who carve holes in trees, ants are ecosystem engineers. They make the environment more habitable for other organisms. Moreover, some ant species utilize dead wood to make their nests. They clean up the environment by breaking down dead organic materials to become more usable for other organisms. Chopped dead wood decomposes much faster than a whole dead tree. In summary, ants fulfill the roles of both ecosystem engineers and decomposers in their communities.
Ants are one of the most social creatures on Earth. They interact with their nestmates and a plethora of other species. Ants form relationships, or symbioses, with many other organisms. These symbioses range from mutually beneficial, antagonistic, and everything in between. I may go into more detail about these relationships in future posts, but for this one, I want to highlight one of the most interesting symbiotic relationships (in my opinion). Ants and aphids have formed a long-established relationship that fluctuates between beneficial and antagonistic. When it is beneficial, ants will tend to aphids in order to feed on the sugary sweet substance they produce known as honeydew (they will even encourage honeydew production as shown in this video). In return, these ants will guard the aphids from predators. However, sometimes ants get a craving for aphids, so instead of protecting them, they choose to predate them. It is fair to say that ants act as both farmers and hunters in this case. It is impossible not to draw parallels between these complex ant-aphid interactions and the beginnings of agriculture in humans.
Amazing diversity
With over 15,000 known ant species, they are a highly diverse group of insects. It would be impossible to discuss all of them, so I will introduce my top three favorite ant species (as of November 2024) instead. If you want to learn about more ant species, I suggest visiting AntWiki. AntWiki is an online ant encyclopedia that is curated by myrmecologists throughout the world. All of the information presented below is sourced from this website. If you find encyclopedias daunting, I suggest checking out Alex Wild’s website. He is an amazing myrmecologist, entomologist, and photographer, and his ant photos are beautiful.
Asian Weaver Ant
The first ant on my list (and also on my bucket list of species to see before I die) is the Asian weaver ant (Oecophylla smaragdina). In my opinion, these are one of the most elegant ant species in the world because of their gold coloration and green gasters. This species is native to South and Southeastern Asia and Australia. Like other weaver ants, the Asian weaver ant constructs its nests high up in the canopy using leaves and silk. These structures are an incredible sight. However, while these ants are elegant, they are also highly territorial. They can completely dominate a patch of forests and are more than ready to defend their patch with their lives. Luckily, they do not have a nasty bite or stingers, but they are probably best admired from afar to save yourself from being swarmed.
Rough node Trap-jaw Ant
The rough-node trap-jaw ant is a species of trap-jaw ant that is commonly found in South Florida, the Caribbean, and South America. In my eyes, what makes these ants so amazing are their unique mandibles (the mouthparts that you see spread apart in the above picture). Trap-jaw ants keep their mandibles locked open until they encounter a predator or prey. Once threatened, the mandibles unlock and very rapidly snap onto their target. Their mandibles close at a maximum speed of 241 km/h (~150 mph) and with a force equal to 300x the mass of the ant. This is enough force to sever limbs off of other insects. Sometimes these ants use their mandibles to propel themselves backwards away from enemies rapidly. You can see this amazing, and sometimes hilarious, ability in this video.
Florida carpenter ant
https://www.inaturalist.org/observations/55222834
The Florida carpenter ant is a common species in Florida. Like most carpenter ants, they make their nests in dead logs or stumps. This seemingly unassuming ant has made it onto my list of favorite ants because it is the first ant species I ever studied in my bachelor’s. During my studies, I interned in a laboratory that researched the famous zombie ant fungus (Ophiocordyceps unilateralis species complex). This pathogen is commonly found on carpenter ants (Camponotus), and in Florida, it is widely seen infecting Florida carpenter ants. The laboratory kept several colonies of these ants that I helped take care of. My time taking care of these colonies enlightened me on how intelligent and interesting ants are.
To keep our ant colonies happy and fed, we gave them vials of water and sugar water that were plugged with small cotton balls. These cotton balls functioned as a stopper to keep water from escaping, and as a damp object the ants could drink from. While we the ants had a constant source of food and water, they still held their primal urge for escape. To prevent this, we used a substance known as fluon on the walls of their colony boxes. Fluon makes the walls slippery and impossible to climb. One day, we received complaints that carpenter ants were crawling around the ant lab. When we went to investigate, we found that one colony had torn pieces of cotton from their vials and glued them on the wall to make an escape ladder. It was an amazing feat of engineering, but annoying for us as we now had to destroy all future cotton ladders in the making. This incident showed me that ants were smart enough to invent innovative uses for materials in their environment. A singular ant would not have been able to do this, but a whole colony can do amazing things. From that day on, I learned never to underestimate these sneaky little creatures.
To end this article, I want to share a couple of pictures I took of infected carpenter ants that I am very proud of. One day, I will write a proper post on the zombie ant fungus.
