(The Brain Scoop Intro plays)

Emily: Hey, Corrie.

Corrie: Hi, how are you, Emily?

Emily: Good, how are you?

Corrie: I'm excellent.

Emily: So, you called us into your office because you have some ants.

Corrie: I do.

Emily: Live ants.

Corrie: I have two species of live ants that I brought back from Panama for two different research projects that I've been working on.  This one here is actually turtle ants, so I've talked a little bit about those in the past, these are great, you can grab some if you'd like.  And these ants are really beautiful, both in sort of their structure, their anatomy, also because they have this really interesting sets of biology.  So this is the species that glide.  So when they fall out of trees, they use directed aerial descent to grab onto the trunk of the tree, so that they don't fall all the way to the canopy floor.

Emily: WHAT?!  So how do they like, steer their heads and like pheeeeeeeewwww?

Corrie: Yeah, they essentially use their heads and their bodies as like, you know, sails, and then use their ability to sort of maneuver to like--as a rudder, but the reason I'm interested in them is they actually have really cool gut bacteria, and so we're starting to study the diversity of bacteria in the gut and also the functional role of those bacteria.  One of the things that we know about turtle ants is that they're primarily vegetarians.  We wanna answer the question if they're using their gut bacteria to upregulate their diet.  So I would say the turtle ants are a really diverse group, there are about 120 species, but this group here, this is Cephalotes atratus, and it's one of the earliest lineages within the turtle ants, and these actually do scavenge prey.  We know that the sort of additional species that have diversified since this group broke of, they actually almost entirely are vegetarians, and one of the species that I've worked on for a very long time in the Florida Keys, Cephalotes varians, eats only pollen and sugar water, so in that case, we wanna ask the question, are they using their gut microbes to essentially translate that nutrition into all the essential amino acids that they need.

Emily: Wow.  So, so, is the reason that they are primarily vegetarian, not these, but most of the other species, is that why they have small mandibles and I'm not worried about it trying to bite me right now?

Corrie: Yeah, that's a great question.  Yeah, maybe that's why they have small mandibles, I mean, that's an interesting, you know, conundrum.  So there's this question about where do you invest in defense, so do you invest in defense through big mandibles or do you have spines on your body, which a lot of turtle ants have, like these.  Is it a trade-off?  So, is it that you  can't physically invest in all, so you pick which is the best strategy, depending on the natural history or life history strategy of that species. 

Emily: And their strategy is to have spines.

Corrie: This species in fact, they actually have spines on the top parts of their body, so sometimes when you go to pick 'em up, it almost feels like they bit you, but it's really just that you grabbed the spine at exactly the right angle.  We want to study the bacteria that are living inside their bodies, and so, we actually need to dissect them while they're alive, which is unfortunate for them, but in that way, we can actually culture the bacteria that are inside their bodies alive now.  So most of the time when I take ants back from the field, I've already killed them in the field and put them in preservative, and that preserves both the ant but also the bacteria inside their bodies, where if we actually wanna grow up those bacteria, like on plates or in liquid media, we need them to still be alive. 

Emily: Gotcha. 

Corrie: Yeah.

Emily: All right, well, let's--let's see it happen. 

Corrie: All right.

Emily: Maybe not this one, though, I've grown kind of attached to it. 

Corrie: So essentially what I have is just a petri dish with some preservative in it.  What I wanna do is disarticulate parts of her body, and so for me, the parts that I'm interested in is I wanna have an ou--I wanna have a leg just to sort of accommodate for the bacteria that they're encountering in the environment, and then I wanna pull off the abdomen or the gaster is what we call it in ant morphology, pull that off and then start to open that up to get to all the segments of the digestive system, so here goes.  So first thing, I'm gonna do is actually just pull off her abdomen or gaster, you can see there it almost goes flying.

Emily: Wow, yeah.

Corrie: Unfortunately, she's still moving around, and that's the thing that's quite surprising, is sometimes after--if you encounter ants in a battle, you will actually see them still running around without their abdomens on, which is unfortunate, so she's obviously still running around a bit.  And so now, obviously, I've told you that there are specific body segments I want to have, so immediately I want to take that leg and preserve it.  The other thing that I often want is I want the head or the mouth area, because I wanna have some kind of understanding of what bacteria they're ingesting, so what's getting into their digestive tract, which may not become a resident member of their digestive tract.  So in this case, I can either try to dissect out the--what we call the infrabuccal pocket, which is the sort of pouch inside of their head, or I can actually just start disarticulating the entire head.  Keep the head in a separate little container, oops.  Now I actually wanna get into that last cavity, which is the abdomen, to start of start pulling out the segments of the--

Emily: So the bacteria in the abdomen is still alive and that's--

Corrie: It's still alive at this point, right, so I mean, imagine that like, you know, the second that we die, our gut bacteria don't know that we're dead yet, right?  So they have a bit of time before they actually stop working. 

Emily: I never thought about that.  I mean, I know you--when you think about the decay process, it's just a continuation of life in that you have all this bacteria that's working on--on digesting and breaking down all of your organic material, but it's still--that's--I mean, we're--we're--we're just bacteria colonies.

Corrie: Yeah.  And you know, the bacteria that are taking advantage of us transition, right?  So what's living on us while we're alive and helping us process our food is gonna be a bit different than what takes over once we're dead, right?  So now I'm inside the--the digestive tract, and so now what I want to do is that there's different segments in the body, so just like we have our stomach and then our large intestines and our small intestines, ants have similar digestive compartments, and so I wanna sort of tease those apart.  In this case, I'm interested in what's found in what's called their social stomach, or their crop, and that essentially is just a liquid food container, and that's where they can, if they find a liquid food source, they can ingest it and then if they find another member of their colony, they can regurgitate it mouth to mouth, so they can share that liquid food source.  Just to give you an idea of what we're talking about, you can see that it's very small.

I sort of stuck it to the side of this. It just looks like a little, like, white glob, right?   Maybe with a little dark spot?

Emily: Yeah. 

Corrie: So you can see that it's actually quite tiny, that's one compartment of her digestive system.  And so then the other part of the body, like the digestive tract we want is we want the mid-gut and the hind-gut, because we actually know that that's where food processing starts to happen, and so in that case, we really wanna have a clear understanding of what bacteria are there, and so the work that we've done, myself and also a bunch of my collaborators is we've been able to document that a lot of the really interesting bacteria seem to be constrained only to that region, and that they seem to be co-diversifying, or co-evolving with their hosts.

Emily: What?

Corrie: So once they've gotten into that segment, it's essentially like, as the host is--you know, the new species are forming, their bacteria are just tracking right along with the--the hosts. 

Emily: Wow.

Corrie: Which is really cool, right? 

Emily: Yeah.

Corrie: I mean thinking about evolution, so essentially, you have, you know, multiple species all evolving together, and you know, so it's one of those you know, thoughts if we think about it, like, if we were to wipe out any one species, there's never just one species, like, even humans, if we were to wipe us out, all of the mites that live in our fore--our pores, right, they would go extinct too.  Even--all of the bacteria that are found only in human guts, those would go extinct as well, so we're ecosystems in and of ourselves.  You've spent all this time now in the rainforest.  We're just a giant rainforest walking around, right?

Emily: Yeah.  Now I feel like I need to shower a little bit. 

Corrie: No, you wanna keep all those things on you, they're important.

Emily: Yeah. 

Emily: Or I get one of those eyeball worms, worm eyeballs?  Eyeball worms. 

Corrie: Eyeball worms.

(Outro/Credits)

Emily: It still has brains on it.