Eusocial Powerhouses: Ants

[Originally posted to Tumblr in "Solving Cubes" on April 5, 2013]

The strongest and most successful species on the planet tend to be those that are eusocial – that is, they can live in large societies organized into hierarchical divisions of labor. This distribution of strengths serves the ultimate purpose of expanding the society. The thing at stake is never the individual organism or even its offspring, but rather the community as a whole. Such a community becomes a single organism in its own right.

Eusocial animals have fascinated us for centuries. We often see ourselves in them, noticing developments they made long before humans did. The most impressive eusocial animals tend to be insects, who are able to build powerhouse societies that are millions strong. These insects, despite their reputation as having a sort of “hive mind” that we may interpret as collectivist or soulless, exhibit astounding intelligence for their size and simplicity.

Allow me to introduce a series on eusocial animals and their tactics for flourishing. How do these species compare to each other? How to they compare to us, and what can we learn from them?

ANTS
The ant is a formidable example of social cohesion and sheer power. Ants are known for their strength and ability to organize. Though no single species can do it all, the basic physiology and mentality of the ant is so flexible that it can develop diverse strategies for supporting its colony. Many of these strategies are eerily similar to the complex behaviors that allowed humans to conquer the world.

StrengthAnts are notoriously powerful creatures. Naturalist and insect researcher Debbie Hadley explains here how a single ant can lift an object 50 times its own weight. The secret lies mainly in how powerful its muscles can be compared to its body size. Strength compared with a small and lightweight body also allows the ant to run fairly quickly on its small scale. It is true that an ant lifting such heavy objects is comparable to a human carrying a car over her head, but it’s also worth noting that a bigger ant would not be able to exhibit such strength. So no, ants wouldn’t necessarily be able to take over the world if they were human size.

Single ants are often seen using their strength and dexterity to wrestle down insects many times larger than they are. The ant’s true strength comes when it teams up with other ants. One African ant species can form its colonies into rafts that float on water in the rainy season. They hook themselves to one another and become surprisingly buoyant. Each ant will create an air bubble around itself when pushed underwater, which allows the raft to survive as a whole with a collective air pocket around it while submerged.

- 500px.com

WarfareThe most powerful ants in a colony are the warriors, which are hand bred by nurturer ants to grow larger and stronger than the other workers. A common definitive feature of a warrior ant is its enormous head, which is occupied by a tiny brain and enormous muscles that work its huge, piercing mandibles. Warrior ants are the most strongly adept for battle, but any ant has the ability to fight enemies with the help of a colony’s numbers.

Ant colonies organize raids against other colonies and insects. A colony of bull ants can kill an entire hive of bees. Using the strength of their mandibles and sometimes claws on their legs, ants can pin enemies down and puncture their bodies. Smothering an enemy this way kills it quickly. Even a flying insect is vulnerable if it is not able to fly off before a single ant reaches it. Ants can lead strategic invasions and retreats, and they can defend the nest from impressive predators. Some ants can even sting and inject venom into their enemies.

- votingwithmyfeet.com

Social OrganizationAnts predominantly communicate using pheromones. When a warrior grabs hold of an enemy, she will release a pheromone that alerts others to attack with her. In order to keep track of the locations of food sources, ants will leave invisible trails which others follow. They build strategic underground living quarters, with chambers used for different purposes and tunnels linking them to one another.

There tend to be about six types of citizens in an ant colony. Most important is the queen, who is solely responsible for generating eggs and larvae. She is enormous, being tended to by the workers and given enough nutrients to reproduce in massive amounts. Protected along with the queen are her larvae, which are helpless and must be fed by worker ants.

Occupying another caste are the male ants, who are typically only used to fertilize the queen. In some flying ant species, males will fly off to other colonies, but even then they will die after mating with females. Male ants are often referred to as drones.

Female ants, on the other hand, comprise every worker in the colony, making an ant colony mostly an enormous sisterhood. Largest are the warriors mentioned above. Medium in size are ants that take on jobs such as building, transporting food, and reinforcing warriors if necessary. The smallest workers are those that stay deeper in the nest, breaking down food and tending to the queen and her brood. These ants are responsible for raising new generations, and by feeding each larva differently, they have control over the quantity of ants the colony will have in each size and class. If the colony is experiencing increased threats, more warriors will be raised – if threats are low and the focus is on expansion, smaller workers will be in higher demand.

- sunnyscope.com
A warrior ant. That head is all muscle, and those mandibles gonna getcha.

AgricultureLong before humans began centralizing food sources by tending to organisms they would eventually eat, ants were doing the same thing. Many ant species rely on farming for sustenance. Most famous are leaf cutter ants, who bring chunks of leaves into the nest and chew them up into a mush of enzymes. This mush feeds their crop, a fungus that they eat. Remove the fungus from their nest and the ants will die.

Some ants even keep livestock. A popular tradition for several species of ant is to take control of an aphid colony and care for them like shepherds. When well fed, an aphid will produce a surplus amount of honeydew, a liquid rich in sugars. Ants can used this food source by spooking the aphids into expelling some from their bodies, effectively milking them for food. Ants will protect their aphids from enemies, even moving the herd to locations that are safer or richer in nutrients.

- lifescapes.org
An ant tending to its aphid herd, probably harvesting honeydew

AntibioticsSome ants have even developed resistance to disease and pests by coating their bodies with antibiotics. Cameron Currie, a bacteriologist at the University of Wisconsin, discovered that when left unkempt, leaf cutter crops will be overtaken by mold within a few days. He then learned that a waxy secretion found on ants working deep in the nest is actually a form of bacteria present in about half of all antibiotics used by humans. This means that ants were able to evolve a resistance to dangerous organisms in order to continue the safe production of their food, and this bacteria is continuously able to evolve along with the mold it is used to control. It is likely that ants have been using antibacterial technology for 50 million years.

- animals.about.com
Ant drugs look a little like powdered sugar. Yum?

___________

These are a few reasons I have a fearful respect for ants. Maybe evolving to larger sizes would not end up serving them well, but I can’t help but imagine ant societies on a larger scale and trembling at the thought. I picture enormous insects with crushing jaws, motivated by the prosperity of their communities, who would destroy everything we’ve created without remorse and with only a fraction of the intelligence we possess. I appeal to you, evolution, to keep ants small. Probably best for all of us.

Sources:
http://insects.about.com/od/antsbeeswasps/a/10-cool-facts-about-ants.htm
http://www.youtube.com/watch?v=HL3sHuK3iGE
http://www.youtube.com/watch?v=fp8DefiZ9RU
http://www.youtube.com/watch?v=OzIzeFPCFWI
http://www.youtube.com/watch?v=43id_NRajDo
http://www.youtube.com/watch?v=RH3KYBMpxOU
http://www.youtube.com/watch?NR=1&feature=endscreen&v=GhGno2BIts0
http://www.youtube.com/watch?v=7asMhwLWW4M