Summary: How do ants organize all those colony residents? Join Kiersten to find out the amazing answer to this question.

For my hearing impaired followers, a complete transcript of this podcast follows the show notes on Podbean

Show Notes: 

“Tales from the Ant World” by Edward O. Wilson

Music written and performed by Katherine Camp

Transcript

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Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

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Kiersten - Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating. 

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

I feel like we have already talked about so much cool stuff about ants and we are only on episode three. This is going to be quite an exciting series on ants. The third thing I like about ants is how they communicate.

Most of us have probably seen a line of ants moving from one place to another at some point in our lives. We may have stopped to take a look and wonder what they were doing or just walked on by without too much of a second thought.  Either way, your brain probably took a moment to puzzle over what they were doing, where they were going, or how they knew where to go.  

Communication is the key! So, how do ants communicate? Two types of chemical substances lead ants through their lives. Pheromones which are chemical substances passed back and forth between individuals of the same species and allomones which are chemical substance used by other species and used by social invertebrates to hunt prey or avoid being prey.

A quote from Edward O. Wilson about ant communication states, “Among all of the organisms that live by smell and taste, ants are the virtuoso of chemical communication.” End quote. Just a heads up, of you haven’t already figured this out, I will be quoting E.O. Wilson a lot in this series, but he’s learned so much about ants and he is always eager to share that I just can’t help myself. Ants have created a unique chemosensory world that no other creature known to humans can surpass. 

Let’s look first at how those ants traveling in a line know exactly where to go? When an ant colony needs resources they send out scouts to find what they need. When a scout finds what they want, they eat or drink their fill and run back to the nest in as straight a line as possible. The scout always knows where her nest is regardless of how far away they have traveled (we will discuss this in a moment). When she arrives at the nest, the scout will puke all over the floor. No serious, she will gurp up a small portion of what she ingested in front of a few ants and then turn around an head back. Some of her sisters will immediately follow her out. But why? She just came in the house threw up all over the floor and then left! What is going on? 

When that scout regurgitated the resource she found she created a pheromone that simply stated, “I’ve found what we need! Here it is! Follow my trail to find more!” Who can resist an invitation like that? The original scout laid a scent trail for herself by dragging her stinger along the ground to follow back to the resource and now her fellow workers will also follow that trail to help gather more of what they want. E.O. Wilson encourages you to experiment with some sugar water to see this phenomenon for yourself. You can use a drop of sugar water near a line of ants and watch what happens when they find it! Please use common sense if you choose to do this. Be careful to keep yourself and the ants safe from harm.

How do ants identify these chemical signals? Do they have a nose to sniff them out? Sort of. They do not have a nose like a mammal that sticks out on the front of their face. They have antennae. These structures are attached to the heads and protrude out into the environment. The first segment of the antenna is called the scape and it is typically the longest and support the other shorter segments. Collectively this structure is called the funiculus. The funiculus is the “nose” of the ant. It is covered in tiny hairs, knobs, and plates, that detect various chemical substances. The funiculus neurologically transmits the identity and quantity of the substance to the brain. 

The information transferred to the ant’s brain must be analyzed in a matter of seconds with unerring precision to ensure survival of the individual and, more importantly, the colony. Based on the sensory information received, the ant chooses her actions quickly and decisively relying on instinct and current circumstances. If you watch a line of worker ants traveling out and back to the colony, you won’t notice how they are communicating with each other the entire time because they are doing so without hesitating or slowing down. Slow-motion photography reveals the continuous movement of the antennae of each ant. They are swinging their antenna back and forth constantly, “sniffing” each ant they pass, the chemical trail they are following, and their surroundings. 

What happens if an ant from another colony tries to enter a different colony? It’s not a great day for that ant, she will be stung to death. This brings up the question, how do ants recognize each other? They all look the same to us. Do they all look the same to each other? Visually, maybe. But they don’t all smell the same. Using their keen funiculus ants can smell a faker.

Each ant carries a specific colony scent with them everywhere they go. Yes! Ants have BO and it is super important to their acceptance. The ant’s body oils absorb the particular scent of their colony. It’s an identification card or work uniform that says you belong here. If an ant with the wrong odor tries to come into the colony the smell gives them away and they will be attacked immediately.

Okay, I think it’s clear that pheromones are extremely important to ants, but how do they create these pheromones? In the summer of 1958, Edward Wilson decide to answer this question. He chose to investigate this using a colony of fire ants in his lab at Harvard. Fire ants are incredibly good at coordinating search and retrieval expeditions for food resources, so they were the perfect candidate for this research. We know ants lay trails using their stingers. So the best place to look of the origin of the pheromonal substance is in the stinger venom, right? This is were Edward Wilson looked first, but no dice. When he created trails using the venom of a fire ant, no one seemed to care. This was the case with several other glands he found as well. Continuing his search, he finally found something with the potential to be the pheromone producer. A small organ connected to the stinger. The Dufour’s gland. It’s a sausage-shaped speck that is barely visible to the naked human eye. 

Could this be what he was looking for? Turns out it was. It was first described in 1841 and Edward Wilson was doubtful that it was what he was looking for, but sometimes serendipity provides. To confirm his unlikely hunch, an experiment was devised using a Dufour’s gland from a sacrificial fire ant. He crushed the gland and drug a line near the colony. The ants flipped out! They streamed out of the colony and ran up and down the line like their butts were in fire. This was definitely what they were using to create their scent trails. 

The next step was to determine what chemical the Dufour’s gland contained, and then maybe we could talk to the ants. Edward Wilson teamed up with some Harvard chemists who used gas chromatography to determine what was in there. They determined that is was a terpenoid pheromone but as they purified it more and more to find the base chemical it lost it’s potency. It turns out that the substance the scout was using to lead her sister’s back to the resource was a combination a pheromones used to excite, attract, and to lead.

So how many pheromones are involved in ant communication? Edward Wilson’s best guess is between ten to twenty different pheromones. The exact number depends of the species. The most amazing part of this is that ants can create new messages by varying the amount of the pheromones released. For example a harvester ant out foraging encounters a group of fire ants. The harvester ant can release the alarm substance methyl heptanone to, hopefully, repel, the fire ants but also call for help from her nest mates. The intensity of the pheromone tells her reinforcements how far away she is and when they come closer they pick up their pace to rush to her rescue. With one pheromone she’s given three different instructions.

Can ants understand the pheromone language of other ants? Sometimes and this leads to a whole load of trouble for certain ant species, but we’ll tackle that topic in a future episode. We went from something as simple as a scent trail to a whole new animal language in this episode about ants. I’m super excited to share this episode with you, because my third favorite thing about ants is how they communicate.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change. 

Join me next week for another exciting episode about ants.  

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This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.