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July 4, 2024 59 mins

The trap is insidious. But of course it is. It was designed and executed… by ants? In this episode of Stuff to Blow Your Mind, the ant wars continue as Robert and Joe explore some of the possibility that a few formidable Formicidae species actually lay traps. (originally published 01/20/2022)

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Speaker 1 (00:06):
Hello, and welcome to Stuff to Blow Your Mind. My
name is Joe McCormick, and today we are bringing you
an episode from the Vault, an older episode of the show.
This one is called do Ants Make Traps? It is
about exactly that question, whether ants the insect build traps.
This originally published January twentieth, twenty twenty two. Hope you enjoy.

Speaker 2 (00:34):
Welcome to Stuff to Blow Your Mind, a production of iHeartRadio.

Speaker 3 (00:44):
Hey, welcome to Stuff to Blow your Mind. My name
is Robert Lamb.

Speaker 1 (00:48):
And I'm Joe McCormick, and today we're going to be
talking about traps. I think I've mentioned this in some
Weird House Cinema episodes, but for some reason, ever since
I was a little kid, I have always loved movie
scenes where the protagonists build a trap to use against
the villain or the monster. I remember, like Home Alone

when I was a little kid, that whole sequence was great.
It sort of expands to fill my whole childhood impression
of what the movie was. And if you go back
and watch it as an adult, it's kind of weird
that it's only like fifteen or twenty minutes of the runtime.

Speaker 3 (01:24):
In Home Alone. Yeah, yeah, yeah, it does seem like
that's the main thing I remember. Yeah, they the traps,
the traps, and certainly people feel certain nostalgia for them.

Speaker 1 (01:35):
My heart swells at the thought of a nail going
into Daniel Stearn's foot. But also, yeah, I remember other ones,
like you know, Arnold Schwarzenegger builds a bunch of traps
and predator. But like, this wasn't just when I was
a kid. It still works on me. I remember there
was a sequence I just loved in the more recent

horror movie It follows where the characters build a trap
for the last year.

Speaker 3 (01:59):
Yeah, that's right, that is very They have a very
much a kind of home alones setup that they do there.
Of course, it's not only the heroes that have traps.
I always love a good villain trap as well, especially
the trap door. And the trap door sequence is always
a lot of fun, you know. Be it something like
in Lynn Labyrinth. I love the trap when the trap

door springs on our hero and that. But actually Tomorrow's
Weird House Cinema also has a fun trap door sequence.
Oh yeah, so look forward to that. Well.

Speaker 1 (02:33):
Yeah, on side of the protagonists getting through traps set
for them, another one of my favorite movie sequences as
a child was the beginning of Raiders of the Lost Art.
Oh yeah, and when INDI's going through all the traps,
something about it is just like, deep in the brain,
it's very satisfying.

Speaker 3 (02:50):
Wall to wall traps. Yeah, that's that's a great sequence
as well. And all of these are great sequences in
spite of the fact that when you when you can,
when you really think long and hard about any of
these scenarios, you know, the cracks definitely show would all
of these traps still be working in this ancient ruin

that Indiana Jones finds himself in. I don't know, it's
a hard argument to make there, right.

Speaker 1 (03:17):
How did the spring trap operate by you sticking your
hand through a shaft of light when it was made
like thousands of years ago?

Speaker 3 (03:25):
Yeah, Or you know, if it's duke and predator, like,
how does he how does he make this super powerful
compound bow just in the space of a few hours
on an afternoon in the jungle.

Speaker 1 (03:36):
That's just standard survival training.

Speaker 3 (03:38):
I mean, and all these other various e Wok traps
that he builds didn't didn't you go to that camp?
Did I build a bow like that at a cat camp. No,
I think we sharpened sticks, you know, that would be
that would be more believable. Right, he makes a spear, Yeah,
to battle.

Speaker 1 (03:53):
That's most of the way there.

Speaker 3 (03:54):
Yeah, But you know, I think it probably speaks volumes
for humans to be you know, to be said all
of this about traps, and especially about you know, loving
these cinematic treatments of traps, because because what are traps? Ultimately,
very broadly speaking, they're clever, tactical and or technological innovations
that level the playing field against predators, against prey, and
even against fellow humans. Traps are the sort of things

that humans have been up to since prehistory. So of
course we love traps, and of course we admire things
like traps that we find in other species.

Speaker 1 (04:26):
Right, So today we're going to be focusing on some
allegations of insects with the ability to build traps, specifically
ants that do things that may in fact be biological
evolutions that allow them to trap prey. Now, there are
some other animals that I think we could say more

more clearly and famously create traps. I think the obvious
example here would be spiders.

Speaker 3 (04:53):
Yes, yes, spiders are the trap builders par excellence. You know,
there are no finer trap builders in the animal Maybe
you could make a case for human beings, but personally
I'm not in favor of that. I think web building
spiders especially are just such highly evolved trap masters. Every
detail of their anatomy and behavior enhances their trapping ability,

and the trap is very much an extension of their
own bodies in so many ways. And we've covered this,
and we've covered spiders in general numerous times in the
show before, and we'll likely keep coming back to them.
But yeah, the spider, the spider is the trap maker.
There's nothing else that the spider really does. Anything else
it does the web building spider is going to do

in close proximity to the web that it has built.

Speaker 1 (05:41):
Yeah. Another example that's come up before, I think in
our Sarlac episodes was the ant lion.

Speaker 3 (05:48):
Yes. Yeah, this is a case where we have predatory
larvae that in some species of antlon anyway, set up
at the bottom of sand pits that they dig, ready
to lack shout at anything that disturbs their grains and
you know, ventures down into the trap. Again, not all
ant lion species dig trap pits, but some of the

most famous ones.

Speaker 1 (06:10):
Do I remember. One of the great things we learned
about the ant lion was that, like you say, it
is the ones that make traps. It is just the
larval period of their lifespan, their life cycle that they
make the traps. Then they later metamorphosed into another form.
But while they're in that larval stage, I think at

least some of them never poop. So yeah, yeah, catching
ants and eating them and just like waiting, and it's
like if you had to wait until you turned eighteen
to poop.

Speaker 3 (06:43):
We'll go back and listen to that Sarlac episode if
you'd like to hear more about the ant lion. There's
also the species of creature known as the worm lion,
and this is unrelated to the ant lion. It's just
a matter of convergent evolution that he ends up utilizing
largely the exact same method again when it's a larva,

though the pit itself in this case is generated via
a slightly different method, so it digs its pit in
a slightly different method, but it still consumes its prey
in the same manner.

Speaker 1 (07:15):
But for me, at least, if you ask me to
make a list of non human animals, that make traps.
I could obviously go spiders. I would have thought of
the ant lion, maybe by association the worm lion. But
there before I was reading up for this episode, I
think I would have drawn a blank. I wouldn't know
what to go to next.

Speaker 3 (07:34):
Yeah, and part of it comes down to just how
are you going to going to define a trap? For example,
Here's here's an interesting potential example we can discuss that
I read across read about when I was reading Gilbert
Waldbauer's How Not to Be Eaten, which is largely about insects,

but there's a part where the author is discussing the
burrowing owl. So these are small birds native to the
Great Plains in southern Florida. I think they're about the
size of a robin. I'm to understand that, you know,
the small, little little guys. But they make their home
in burrows that they did themselves. And one of the
interesting things that they do in addition to this, if

this wasn't you know interesting enough already, is the burrowing
owl will scatter horse or cow dung around the entrance
to their burrows. And then, you know, times before European contact,
this would have probably been bison dung, and the dung
does seem to be important because if researchers remove the
dung from the vicinity, the birds will just the bird

will just go out and obtain more dung and place
it in the vicinity. So it seems to be doing
this intentionally. The theory is that they place the dung
to bait dung beetles. So they put the dung out,
dung beetles come, And indeed researchers have been able to
tell that the owls eat ten times more dung beetles

than usual when the dung is out.

Speaker 1 (09:02):
Ah. Well, this will in fact mirror one of the
two examples of potential ant trap making that I want
to talk about later.

Speaker 3 (09:10):
Yeah, I mean it's but this is a great example.
It's certainly clever. I like it. But it kind of
forces us to ask the question of a trap, like
what is a trap? Is it merely baiting a trap?

Speaker 1 (09:23):
That is a good question, yeah, because and how much
does the trap structure have to be separate from your
body in order to recount as a constructed trap? And
how much does it have to how much work does
it have to do for you?

Speaker 3 (09:37):
Yeah? And at what point does an animal's behavior stop
being a trap and just become sneaky behavior, sneaky tactics,
or simply ambush predation, because obviously there are plenty of
examples of ambush predators on land and in the sea,
and these include everything from well, the trap door spider
for one, which I think is definitely a case of

building because it's an ambush predator, but it builds a
silk hinge trap door to aid in those ambushes.

Speaker 1 (10:07):
Right, so the trapdoor hides it. I think you could
count that as like infrastructure necessary to constitute a trap.

Speaker 3 (10:13):
Yeah, yeah, I think that, Yeah, definitely with the trapdoor spider.
But then you also have just various camouflage predators, including
things like frogfish, praying mantis's, chameleons, and more, which are
not building anything. They're not altering their environment, but they've
evolved to look like a part of their environment and
they have the you know, often tremendous abilities of camouflage

that enable them to quickly ambush something that they want
to eat.

Speaker 1 (10:40):
Okay, that probably doesn't That doesn't really seem like a
trap to me, because they're just evolved to look that way,
and they they do the actual hunting themselves.

Speaker 3 (10:50):
Right, And then of course you have various birds and
cats and big cats even that are just very stealthy,
that are just very good at not being observed by
the things they want to kill. So I was reading
a little bit about this in Douglas j Imlin's excellent
book Animal Weapons that have referenced on the Show before,
and he points out that creatures such as this generally

depend on quote, a quick strike weapon that immediately incapacitates
its victim. And of course these bioweapons might be enhanced
by special features, such as in various deep sea ambush
predators a bioluminescent lure, which again is not something they
have created or engineered out of their environment, but it
is a part of their body. So when we come
back to this idea that what it needs to be

something that's built, it needs to be something that's engineered,
or just a hole dug in the ground, even we
come back to that same question, well, why don't we
find more of this? And I actually found an interesting
paper title out there, Why are pitfall Traps So Rare
in the Natural World? By G. D Ruxton and MH. Hansel,
And it appeared in evolutionary ecology in two thousand and nine.

Speaker 1 (11:56):
Interesting question.

Speaker 3 (11:58):
Yeah, So the authors here point out that in order
to lay a trap, you generally need either advanced cognitive
powers as with humans obviously, or you need specialist self
secreted materials as with spiders and cattisfly larvae, thing which
the catasi fly larvae use that their their secretions to

create a net like even meshed trap like a silk trap,
in order to filter catch their prey.

Speaker 1 (12:27):
That makes sense. So humans can create all kinds of
traps because we have, you know, cognitive powers that allow
us to imagine what could be done. How you know,
other materials in the environment could be repurposed to passively
ensnare or kill prey animals and spiders and stuff. That's
just the trap you could almost say, is a part
of their body. Even though the web is a built thing.

They revolved to secrete the silk for the web out
of their bodies, and they have very instinctually driven behaviors
for how they extrude that silk wear in what patterns.

Speaker 3 (13:01):
Right, So, Ruxton and Hansel here ultimately point out that okay,
we have the ant lion though, and of course the
worm lion. These are exceptions to the rule. They make
use of a pitfall trap, and so the authors ask
why is this basic tactic not more common in the
animal world? How hard is it, after all to dig

a hole? They're easy, they're cheap, and yet you don't
see this technique used by virtually anything outside of some
ant lions and worm lions. Apparently, the lack of more
pitfall traps than nature was something of a mystery and
remain something of a mystery.

Speaker 1 (13:40):
Yeah, that is interesting, Okay, so it took me a
second to get the distinction they're making. But they're saying
that the ant lion and the wormline would be kind
of an outlier because they don't have complex intelligence and
imagination like humans, so they're not inventing traps with cognitive powers.
But they also don't secrete a material that CONTs institutes
the basis of the trap like a spider. They're literally

just building a trap out of the dead environment around
of them by digging a conically shaped hole in such
a pattern that ants get stuck in it when they
fall down the side. And why is that so rare,
because it would seem like that that should be a
strategy that lots of animals could easily employ.

Speaker 3 (14:20):
Right, Yeah, again, holes are ultimately easy to make, low energy.
Why not? Why why? Why why is this cat not
making a hole and using that as part of its
hunting tactics?

Speaker 1 (14:31):
So what are their thoughts on this, like, why would
why wouldn't we see this more often?

Speaker 3 (14:36):
Well, they proposed two speculative reasons for the lack of
pitfall traps in nature. The first one is pitfall traps
may require a specialist micro habitat. In other words, you
can't do this just anywhere. Conditions have to be just right,
such as you know, we can look at to the
ant lions, they have to be kind of sandy conditions.
You know, you have to have that kind of granular environment.

So it's the kind of tactic that a potential trap
builder would not necessarily be able to employ all over
the place. You would have to depend on again, on
a specialist micro habitat.

Speaker 1 (15:08):
I think I recall from our Sarlac episode where we
had a segment about the ant lion that they needed
the grains of soil to be of a particular size,
like the sandy grains above or below a certain diameter
threshold would not work very well for making the traps.

Speaker 3 (15:25):
Yeah, yeah, Now the second point is that with the
ant lion in particular, the trap target's small prey, and
since they may be more functionally tied to their trap
than spiders are, traps of this nature could serve as
like basically a major bull's eye for potential predators. And
indeed the main predators of ant lions and worm lions
are birds who know what to look for.

Speaker 1 (15:46):
That's a really good point. So by building a trap
and then sitting in it and waiting for your prey
to fall in, you were also usually going to be
making a structure that makes it easy for things that
want to eat you to define where you are. You know,
they don't have to look too hard because you've made
a big hole in the ground.

Speaker 3 (16:03):
Right and and spiders just have a little more leeway
with the situation. Now, I should point out Hansel also
wrote an entire book which I'm going to reference here
in a minute. He spends a lot of time in
that book talking about spiders and how, you know, sometimes
spider webs are very visible and other times they are not,
and how that plays into the you know, the ultimate

kind of complex relationship between spiders and the creatures that
would eat spiders. But just thinking about this as the
trap being this conspicuous thing. This we actually see this
in a lot of our fantastic trap fiction. You know
that moment when the target of the clever cinematic trap,
especially if it's laid by the protagonists, the enemy almost

sets it off, right, like the predator almost triggers the
trip line you've prepared. But then something happens, right the
monster deduces that the trap is there, or it suspects
that something is off.

Speaker 1 (17:00):
Oh, and maybe even the presence of a trap is
how the hero knows that they have stumbled across the
bad guy's hideout.

Speaker 3 (17:08):
Yeah. Yeah. It even reminds me a bit of our
recent weird house selection, The Lift. This was the Killer
Elevator movie, the Killer Elevator in this or I guess
you were more specifically the weird biobrain that's been installed
in the elevator shaft to power these elevators. It's kind
of an obligate trap predator, but it's so tied to

that environment that it's a little tricky, like it's not
able to pull off every kill, and it's eventually destroyed
by prey that is too clever for it.

Speaker 1 (17:40):
Brilliant analogy. This is true. The killer elevator is an
obligate trap predator.

Speaker 3 (17:47):
I also have to point out, speaking of the Sarlac,
is that recent Mandalorian episodes have also sort of played
with this idea. Yeah, yeah, the Mighty Sarlac. The Startlack's
pretty impressive, but they make it clear that even these
great trap predators can be a soom by the mighty
create dragon that lives in the deserts of Tatooine. So
knowing you're there being you know, this identifiable organism in

the sand, that can have a huge downside to it.

Speaker 1 (18:12):
Now, I was trying to think of counterpoints to the
idea that. Okay, so sitting at the bottom of a
pitfall trap and waiting for prey to fall into you
and then eating that that makes you vulnerable to predators
that want to find you. Well, well, what if you
just make pitfall traps and then you go away and
then you know, leave them there and then come back
like a human hunter might do, you know, leave a

trap out in the woods and then come and see
what it collected lobster traps or something. But I can
see downsides to that as well, because if it's just
a pit trap, you could imagine that, well, something might
fall in there, but then something else might eat it
before you get to it, right, so, or it might
you know, if you have to make these all over
the place, you might spend a lot of energy going

around from one to the other. So is that really
all that much better than just hunting?

Speaker 3 (18:59):
Well, and then it kind of comes back to this
idea that the trap laid by an animal especially still
requires the lethal mechanism, and in the case of the antlime,
the legal lethal mechanism is itself. It is still essentially
an ambush predator like again, like Emmilin says, quote a
quick strike weapon that immediately incapacitates its victim.

Speaker 1 (19:21):
Yeah, I can't believe I didn't think of that. That's,
of course a good point. You have to find a
way to kill the prey, right.

Speaker 3 (19:27):
So I mentioned that that Henzel has a whole book
that deals with with some of this a little bit,
but just sort of the broader picture of animals building things.
It's titled Animal Architecture, and I was reading through this
a bit. He contends that we're not looking at traps
when we're looking at cases of an animal baiting another animal,
because traps are a kind of subset of animal architecture,

an engineered space that aids in capture.

Speaker 1 (19:52):
Okay, so by his metric here, what the burrowing owl
does by leaving dung out around its nest and having
this attract insects to it, that would not count as
a trap because it is not a structure that in
any way aids and capture. It just attracts prey to
a site.

Speaker 3 (20:10):
Oh, by the way, I want to also, speaking of
the burrowing owl again, I want to throw in that
while some burrowing owls do build their own burrows, they're
also burrowing owls that acquire the burrows of other creatures. Anyway,
I want to read this quote from Hansel here. I
think he puts it rather well concerning the animal architecture
and traps quote. Whereas a house can just be a

barrier between the builder and the outside world, a trap
has a dynamic relationship between itself and the prey. The
prey needs to approach the trap in a particular orientation
to it, and then needs to be restrained by it.
Traps are therefore more complex than homes and need to
be more precisely engineered, and then he goes on to

point out the quote among the vertebrates, trap builders were
apparently absent until the recent history of man. Now he
cites human mental capacity once more for the construction of
such traps, noting quote, Virtually all non human trap builders
use self secreted materials, and the capture principle they adopt
is the net. Exceptions are simple in design and operation,

as well as rare, and then he goes on to
specifically mention antlions, worm lions, and larval diptra.

Speaker 1 (21:31):
But anyway, a large takeaway here is that trap building
is not as widespread in the animal kingdom as you
might expect. Humans make a lot of traps. There are
some very specialized animals, especially some invertebrates, that use traps
made of materials that they secrete from their own bodies,
but generally, trap building is not a very widespread hunting

strategy among animals of planet Earth, in which case it
would be very interesting to find examples of animals such
as ants, that make traps in order to get their nutrition.
And I guess that's a good segue to what I
to the main focus of today's episode. Which was a
couple of examples I came across of ants that do
something that could be interpreted as building traps as a

hunting strategy.

Speaker 3 (22:19):
Yeah, and I mean it would make sense that we
might find something like this in the ant world because
ants are masters of construction, they alter their environment, they're
capable of practicing agriculture. They as we've discussed in previous
episodes of the show, they engage in complex conflicts that

we might well compare to warfare. They can solve problems there.
I mean, the list goes on and on. Ants are
amazing as of course, as the now Light e O.
Wilson was fond of reminding us, you know, ants, there
are incredible creatures that we've covered them numerous times in

the show before, we're covering today, and I'm sure we'll
cover them again exactly.

Speaker 1 (23:03):
So the first example I want to talk about I
found so interesting, and this one also has some interesting
differences in interpretations I came across. But just to start
with the basic report. I was reading about this in
a paper published in Nature in the year two thousand
and five by land Jan Pascal, Jean Solano, Julian Irole,

Bruno Corbara and Jerome Oreville called arboreal ants build traps
to capture prey, and also as a supplement to the
paper in Nature, I was reading a summary feature that
was also in Nature by NoREL Tawi, published in April
two thousand and five, called Amazonian ants ambush prey. So

here's the deal. There's a plant in the Amazon called
Hertella phisofera, or maybe Phisophora physo phora. I'm going to
try to say fizzof so these here Tella plants. Plants
in this genus are woody trees or shrubs. I've seen
them called both trees and shrubs, but they're if you're

trying to picture them as a tree, you should be
imagining a small tree, so woody stems, but not like
you know, sky high. Plants in this genus are found
in the tropics across multiple continents, but their diversity is
concentrated around the Amazon, and they typically have flowers that
are pollinated by butterflies. And this one species in particular,

here Tella physophera, is what the authors of the paper
call an ant plant. This is a plant species that
is known to have a specific biological relationship with a
species of ant and these can be found throughout the world.
There are very common mutualisms, or you know, various kinds

of symbiotic relationships between ant colonies and the trees or
plants they inhabit. Now, this plant in particular has a
relationtionship with the arboreal ant alomeras decim articulatus, and they
live on the body of the plant, forming colony centers
in what the authors of the paper call leaf pouches.

They are these little bulb looking things that can usually
be found at the places where the branches split into leaves.
They look like these it's kind of hard to describe them.
They're just these little like green lobes or orbs, and
apparently the ants like to get inside those and make
nests in there.

Speaker 3 (25:31):
Now. Already, one of the things that's that I'm reminded
of is the idea of like a specialist micro habitat.
And if you have a situation where a plant is
the home to the ants, that they have this ant
plant relationship in place, you know that the plant itself
is kind of the environment, it's kind of the micro
habitat that the ant is the master off.

Speaker 1 (25:53):
That's exactly right. But the interesting thing is of course,
ants being builders, some ants will form complex, you know,
dugout colonies in the ground or other types of interesting
engineered environments. They can also engineer the microhabitat of the
surface of a plant, and that's what we're going to
be talking about in this case. Oh and I should

say that the colonies that were looked at in this
two thousand and five paper were from French Guyana in
northern South America. But so what you find in these
plants that are occupied by their familiar ant species is
that along the stems of the host plant, the ants
will build what the authors of this paper call galleried structures,

or sometimes they just say galleries. It's kind of hard
to describe exactly what this is, but imagine a kind
of platform built out over the surface of the stem
of the plant, and it's a platform that the ants
can crawl underneath. And then this platform has a kind
of spongy texture, almost as if fits or honeycomb texture.

It's aligned with all these holes in the platform that
the ants can crawl in and out through. Generally the
holes are just slightly larger than the diameter of one
of the worker ants heads. So through these platforms raised
above the stem of the plant. Ants crawl underneath them,
but then crawl up and up and down, in and

out through the holes in the platform.

Speaker 3 (27:25):
Yeah, it is kind of difficult to describe it because
it is so different from something that that humans would
for the most part build, you know, by virtue of
the ants being far more mobile and sort of living
in a more three dimensional space than human beings tend to.

Speaker 1 (27:42):
By the way, these are great to look up, probably
unless you suffer from trip to phobia, in which case
stay far away.

Speaker 3 (27:48):
Yeah, if you're if you're freaked out by things like
lotus pods and random holes and things, yeah, you might.
You might want to avoid this particular Google image search.

Speaker 1 (27:58):
Now, how do the ants build these galleries, Well, they
apparently make them by cutting off tricombs from the stems
of the plant. Tricombs is a word that comes from
the Greek word for hares. These are small, little fibery
appendages that poke out from the surface of a plant.
You've probably seen lots of plants before that have little
hairy things all over the stem or the leaves. Those

are tricombs, and they do look a lot like hares.
So the worker ants will move along the stem of
a Hairtella physophera plant, clearing away the tricombs, and then,
just to read from the language used in the paper here,
quote then using uncut tricombes as pillars, they build the

galley's vault by binding cut tricombs together with a compound
that they regurgitate later. This structure is reinforced by the
mycelium of a complex of sooty mold species that has
been manipulated by the ants. Fungal growth starts around the
holes and then spreads rapidly to the rest of the structure.

So I think you heard that right. So these ants
build their galleries along the stem of the plant by
cutting the hairs off of the plant where they live,
then using those hairs as building materials, along with their
own barf as a kind of mortar, and then holding
everything together by seating it with mold or fungus that

they farm. So they have a kind of agricultural project
for farming fungal rebar that they use to reinforce the
galleries that they build. And in quotes given to the press,
I've seen the authors of this study compare this composite
material to fiberglass.

Speaker 3 (29:44):
Wow, Yeah, that does seem like a good comparison. Oh man,
I mean, it's just so amazing that it's not just
like this physical act, but they're actually yeah, seating it
with with this this mold. Oh man, they're kind they're
build it, but they're also kind of growing it.

Speaker 1 (30:03):
Be amazing, and they tend to it as it grows.
So I wanted to read another section from the study
where they talk about the evidence that the ants are
actively tending the fungus as it reinforces these structures. They say, quote,
we noted that the stems of thirty four young seedlings,
which had not yet developed leaf pouches, did not bear fungus.

Nine saplings raised in a greenhouse in the absence of alomeras.
That's the ants developed leaf pouches but never bore fungus. However,
fifteen saplings raised in the presence of ants bore mycelia,
whose development was limited to the galleries. When we eliminated
the associated ants from five of the fifteen, the fungus

on the galleries grew into a disorganized structure, and none
of the nine new stems that developed bore any fungus
at all. Okay, so the fungus is only showing up
on the plant when the ants are there on the plant.
And if you take the ants away from the plant
after they've been using the fungus to reinforce their their galleries,
the fungus kind of grows out of control in what

they call a disorganized structure. But with the ants still there,
it stays nice and tightly formed around the holes in
the galleries. So they're tending their garden. It's like a
living I don't know, it's like if you had to
have maintenance workers constantly sort of gardening and tending to
the fungus that held up your skyscrapers.

Speaker 3 (31:30):

Speaker 1 (31:31):
But here's where we start getting to the trapping. So
the authors of this study say that they noticed that
sometimes larger insects would become immobilized on the surface of
the galleries. So you got these these spongy surfaces, ants
crawling underneath them, and sometimes like a locust or a butterfly,
some bigger insect lands on the gallery and then it

gets stuck. What's going on here, Well, they started to
investigate whether the galleries could be functioning as a type
of trap. And here's what they say about how the
ambush works quote. Our observations revealed that Alomiras workers hide
in the galleries with their heads just under the holes,
mandibles wide open, seemingly waiting for an insect to land.

To kill the insect, they grasp its free legs, antennae,
or wings and move in and out of the holes
in opposite directions until the prey is progressively stretched against
the gallery and swarms of workers can sting it. The
ants then slide the prey over the top of the gallery,
again moving in and out of the holes, but this

time in the same direction. They move it slowly towards
a leaf pouch where they carve it up. Oh and
then once they get to one of these population centers
of the colony, you know, the these nest sites in
the leaf pouches, they tend to feed bits of protein
from the insect to their young.

Speaker 3 (32:56):
Well, yeah, this is amazing and suitably brutal for the
world of ants. So this, this larger creature lands or
walks on to the structure. You know, they're reaching out
of holes to pull it straight down, and then they
transfer it to a place where they can carve it up.

Speaker 1 (33:14):
Right. So yeah, there's no sentimentality in the world of ants,
they're just like, okay, this is edible, It's time to
get to butcher in But anyway, these observations reveal this
fascinating three way interaction between the plant, the fungus, and
the ant all sort of living together in this this
three way life cycle. Essentially that apparently serves the purpose

of creating a trap to get larger insects. You know
these Oh I don't think I mentioned, but the Alamiris
decim articulatus ants are very small. It's a structure that
allows these tiny ants apparently to capture kill and butcher
much much larger prey.

Speaker 3 (33:57):
All right, And of course the plant out of all
of this gets some slight mutilation from the ants, but
is protected from larger insects that would otherwise no on
it and do more harm to it than just creating
an interesting lattice work out of its body.

Speaker 1 (34:13):
Presumably, I mean, I think often there is such a
relationship going on. The insect also provides a benefit to
the plant somehow, though in the sources I was reading
it wasn't clear to me exactly if it's known what
the major benefit provided by the ants is, but I
would guess that's right, that they're probably protecting the plant

from herbivore large herbivore insects that would chew its leaves
down or something, But I don't know for sure. I
gotta admit right.

Speaker 3 (34:40):
And then of course we also have to always realize
that in the natural world the line between parasitism and
symbiosis is sometimes a bit thin. These are not relationships
that are governed by strict contracts, so you might see
a little bit of push and pull over the course
of evolutionary history.

Speaker 1 (35:00):
Ants will take whatever they can get.

Speaker 3 (35:02):
You're right, so you be careful about entering into a
bargain with the ants.

Speaker 1 (35:08):
But on the other side of all this, I wanted
to come back on it because I found a book
where the trap interpretation of these structures has been challenged.
And in fact, this book was by somebody who's come
up on the on I think episodes we did about
ants last year, the biologist Mark W. Moffatt. Yes, yes, yeah,
So he has a book called Adventures among Ants that

was that came out in twenty ten University of California Press.
And in this book I found a section where Moffatt
argues that the trap interpretation of these structures built by
alameiras decim articulatis is in fact a misinterpretation. Now I'm
not sure he's right about this, but I do want
to explain what he claims, so it's a bit of background.

In the section of the book directly preceding this, Moffatt
has been talking about his observations of various species of
army ants on raiding parties to forage for food and
also on defensive patrols to protect the colony and the
rating column from threats, and one of his observations in

this preceding section is how difficult it is sometimes to
tell the difference between these two behaviors and how easily
one bleeds into the other. So, according to Demoffitt, for
most army ants, their defensive attacks on a creature that
is perceived to be threatening the raiding column can quickly

turn into a foraging raid in itself. So if the
threat is killed, it is pretty much immediately chopped up
into pieces and carried away as food. So it's kind
of like if you imagine every monster movie ended with
the heroes butchering and eating the monster after they finally
defeated it.

Speaker 3 (36:51):
Well, we do see that sometimes. In fact, that occurs
in the Mandalorian but the case of the Great Dragon.
But but yeah, we should see more consumption of the
d of dragons and monsters and so forth. Use every
part of the monster be responsible.

Speaker 1 (37:07):
Well, I don't know. I mean that's you know, humans
are different than ants. I mean, ants are not going
to let anything go to waste. Humans, after you've fought
a monster, you might just want to have nothing to
do with it. To each species their own. But anyway,
so from here, Moffat moves on to describing the ant
I've been talking about Elimeris decim articulatus, and he's describing

its living situation. The one distinction he makes I couldn't
find out what was what was the disconnect here? But
he said, you remember how I said that the ants
build these gallery structures out of tricombes cut from the plants,
a little plant hairs, mixed with their own regurgitation or vomit,
and then lined with the mycelium of the fungus that

they cultivate. Mofatt describes it the same way, but he
mentions feces rather than vomit. And I don't know who's
right there. But anyway, Moffatt gives a few reasons that
he had doubts about the generally accepted interpretation of this
structure as a trap, specifically as a trap, because he
says a trap implies that, for example, a locust landing

on the ant gallery would not have landed there if
it saw the ants. The trap would be performing the
function of hiding the ants, so you know, they're hidden
beneath the vault of the gallery, so that the prey
insect feels it's safe enough to land and then they
jump out and grab it.

Speaker 3 (38:29):
Okay, this would be in keeping with say the trapdoor
spider would probably be a great example of this.

Speaker 1 (38:35):
Yeah, yeah, I think that's comparable. That's how it would
function as a trap. But Moffitt writes that he thinks
this is unlikely because he doubts that grasshoppers would really
be able to notice the tiny workers of this ant
species anyway, quote particularly in mid leap, or that they
would be able to change course in mid leap after

noticing them. So he was a little iffy on that, like,
I'm not sure that the trap would really serve much
purpose if it's supposed to be hiding the ants from
the prey animal, because these are insects that are much
larger than the ants anyway.

Speaker 3 (39:11):
Right, So he's saying, basically saying like this might be
if this was a trap, which he doesn't think it is,
it would be a preposterous trap, an unnecessary trap. And
while again we love unnecessarily complex and preposterous traps in
our cinema, we're not talking about cinema here. We're talking about.

Speaker 1 (39:29):
Evolution, yeah, and sufficiency.

Speaker 3 (39:32):
Yeah yeah. Things need to be ruthlessly efficient, and if
it's not ruthlessly efficient, it is going to change or
go away.

Speaker 1 (39:38):
But anyway, those are his suspicions, so he decided to
put them to the test. So he tells a story
of that he was studying colonies of this ant in
the wild in Ecuador, and he put together a test
to interrogate the trap interpretation. So to read from the
section of Moffitt's book where he describes this test, he says, quote,

hung a mosquito net over a plant with a thriving
alomeras colony, added one hundred grasshoppers and katie diids, and
sat inside for the next five mornings. An unusual case
of using a mosquito net to keep insects in instead
of out. Even after the grasshoppers settled down, they were
indiscriminate in their movements, hopping from where the ants hid

under the structures to where ants strolled in full view,
to where there were no ants at all. When they
landed among the ants, even on the structures, they got
away unhurt. Certainly, if the structures served as traps, they
were inefficient ones. So he's saying in his observations here,
he's seeing very little correlation between the structures and the

hunting behaviors of the ants or the behaviors of the
prey insects. So what purpose does he believed the galleries
are serving. Well, he points out that the galleries tend
to run along the stems of the tree, connecting each
nest pouch to another nest mouch, and they quote contain
a highway of workers commuting from nest to nest. And

then he points out that other insects, including other ant species,
do sometimes build various types of physical covers over their trails,
which are generally interpreted to be defensive in nature. For example,
some marauder and driver ants have been observed to build
soil covers over their trails, So could that be what's

going on in this case? Could these galleries that the
ants build actually be defensive in nature? Another strike here?
According to Moffat, he observed that the workers at his
study site did not actually sit and wait at the
holes in these galleries, as you might expect them to
do if they were planning an ambush. He says that
when conditions were normal, so like if the colony is

not in an agitated state, things are just sort of
going along normally. Most of the gaps in the gallery
structures were unoccupied. But he says this chain when there
appeared to be some kind of threat to the colony. Quote,
after a day of pulling grasshoppers from my hair, I
noticed interlopers of another ant, a species of Fidolei or

big headed ant, climbing the plant to pin down a
wounded grasshopper missed by the Alomiras. Upon the arrival of
the fidole ants, the Alomiras workers began to guard each
of the several dozen entrances to their arcade. And that's
the arcade, is what he's calling the things that the
other authors called the galleries the several dozen entrances to

their arcade nearest the commotion caused by the intruders. These guards,
aided by nest mates roaming the arcade surface, also caught
and killed one fidoli and carried it off. So, based
on these observations, moffittt argues that the galleries are more
likely defensive to protect trails of workers moving from one

leaf pouch to the other, but that when something attacks
or threatens the colony, the workers quickly shift their behavior
from travel to defense, and then they occupy the holes
and start biting violently at anything that comes near. And
of course, if they are able to immobilize an attacker
or not necessarily an attacker, if they're able to immobilize

whatever it is that put them on the defense, they
immediately shift rolls again and turn that threat into food
and begin butchering it for the colony again, to cook
the monster, so to speak.

Speaker 3 (43:27):
So we might be better to think of these as
defensive fortifications, kind of like to use like a medieval
castle or fortress scenario. It's kind of like the various
crinolations and murder holes and arrow slits, except with the
added point that in this case the occupants of the

castle or fortress would eat those that they killed defending it.

Speaker 1 (43:51):
Right, That's what Moffatt argues, And so to finish up
his section, he says in the end, quote in this
way the organization of a super organism, referring to ants.
There because I think you can make the argument that,
you know, an ant colony might be best understood as
one organism rather than many. It is a super organism
composed of many different bodies, he says it quote can

be more responsive than the tissues in a body. Trail
Bound workers can shift seamlessly in their behavior from transport
to protection to predation. It's as if one's liver could
change function when the heart is incapacitated and pump blood.
So obviously I don't know who's right here. Moffatt's book
is more than ten years old at this point, and

most of the things I read about this ant species
alomeris decim articulatas still describe the galleries as ambush traps.
And I'm not sure which interpretation is correct, but I
do think either way, Moffatt makes a very interesting point
about the fluidity of function when it comes to ant behavior.
How you know one moment's enemy is the next moment's lunch.

Speaker 3 (44:57):
Right, Yeah, Like the ant colony is not just trying
to do one thing. It has a lot of objectives
and it has again this fluidity of function. Whereas it's
far easier to look at a web building spider and
know what's up. You know that the web is its purpose,
the web is kind of its sole, and there's no

question about why it constructed the web.

Speaker 1 (45:22):
I guess. Also, this raises another question about what counts
as a quote trap because assuming for a second that
Moffatt's interpretation is correct, I don't know it is, But
if he's right that these structures are primarily to defend
the ant trails, but then when something when a threat
presents itself, they turn around and use the holes in
the galleries as murder holes and then eat whatever they

can immobilize, does that count as a trap? Like how
specialized does a structure have to be for the purpose
of catching prey in order to be thought of as
a trap, Because you can imagine other examples where an
animal builds a structure that's primary defensive in some way,
it's more like the home from the example you talked
about at the beginning in that book. You know, it's

a barrier between you and the outside world. Yet it
has some kind of feature that like another animal or
something could get stuck on or some you know, it
somehow allows you to sometimes opportunistically harvest from the structure
and then eat from it. And does that count as
a trap?

Speaker 3 (46:24):
Now? I haven't seen this movie in a very long time,
but but I think there might be something comparable in
Home Alone too, am I right? Oh?

Speaker 1 (46:32):
Lost in New York, the one with Tim Curry?

Speaker 3 (46:34):
Oh? What Tim Curry's in that one?

Speaker 1 (46:36):
Oh? Yeah, I think he plays a He plays a
snooty bell hop or something.

Speaker 3 (46:39):
Okay, that sounds about right.

Speaker 1 (46:41):
Yeah, but yeah, I think the Actually, we were trying
to figure this out what this was, and Seth's just
chimed in to let us know he was right. The
house where he builds the traps and Home Alone two
is a house that's like under renovation, so it already
has feature Like, all the traps don't have to be
in from scratch. There are already features of the house.

I don't remember exactly what they are, but there are
things that are dangerous about it already.

Speaker 3 (47:07):
Okay, yeah, yeah.

Speaker 1 (47:15):
But I wanted to talk about my second example of
ants potentially doing something that you could interpret as a
trap ok, and this one also involves using foreign materials
around the nest. So the second example was described in
a paper that I was reading published in twenty nineteen
in the journal Ecological Entomology by Innacio Gomez Diego, Santiago

Ricardo Campos, and Heraldo Vasconcelos. It was called why do
fight oly oxyops ants place feathers around their nests? And
I also got some additional information from reading an article
about the study published in Scientific American by Joshua rapp
Learn in November twenty nineteen. But here's the deal. So

there is this species of ant called Fidolei oxyops. We
were already talking about some fidoli ants in the last
example because the remember the fidoli ants invaded the tree
and then they got kind of butchered by the alomiras ants.
But fidoli ants are a genus known as the big
head ants, and this species, in particular, fidoli Oxyops, is

native to South American savannahs. So these would be you know,
grasslands ants. Sometimes they appear to do something pretty weird.
They collect feathers and place them around the entrance of
their nests. So, if you imagine the nest is buried,
the entrance is basically a hole in the ground, and

then you might just find feathers all around the holes,
scattered around on the ground outside the hole. That's weird.
It might make it look like the ants ate a
live chicken or something, but that is not what happened.
They appear to collect the feathers and put them there.

Speaker 3 (48:59):
Yeah, it kind of looks like there's a hole in
the ground and like a bird was sucked down that hole,
and this is these are the cartoonish remnants of that incident.

Speaker 1 (49:08):
I thought the same thing. Yeah, I was like, hmmm,
pop and then just puff of feathers they settle around it.
But no, that is not what has happened. The ants
put the feathers there. Strange. So this paper published in
twenty nineteen in Ecological Entomology, it claims that these feathers
function as bait to attract prey animals, which then tumble

into the nest entrance as if it were a pit trap.
And the Scientific American article actually reports a bit of
the background on the paper. It says that the studies.
First author in Nacio Gomez, is an ecologist at the
Federal University of Visosa in Brazil, and while walking around
city parks and his college campus, he noticed examples of

these ant nest entrances with feathers all around him. Apparently
this had been observed, and also I was looking at
another paper about this ant species, fidally oxyops. This one
was by Diego asis at All from twenty twenty one,
and this paper said that in addition to feathers, there
will sometimes be other objects around these entrances, including shells,

flower pedals, and seeds. But this study in particular was
focusing on the feathers, and so he noticed these feathers
around the entrances and he wondered what was the deal
with this. Apparently this had been observed before, and there
were already a couple of untested hypotheses in the scientific
literature about what the feathers were doing there. One idea

was that the feathers could collect do in arid regions,
so they would help provide the ants with water in
the mornings, and the other idea was that some of
the feathers could serve as lures, attracting prey to the nest,
and so the twenty nineteen study tested both. In one experiment,
the researchers supplied the ant colonies with water soaked cotton balls,

so made sure they had access to plenty of water,
but the ants in these cases preferred to collect feathers anyway.
It did not seem like access to water played any
role in their desire to collect feathers, and this could
be evidence that the feathers were not primarily for collecting water.
But another test was designed to see if feathers scattered
on the ground would attract prey. So they tested this

with artificial traps that were made to resemble the nest
entrances of these ants, and the team found that if
you put out a trap and scatter feathers around it,
for some reason, it will tend to trap more just
sort of wanderers, you know, arthropods that are out on
the ground, than traps without feathers, And so interesting question

why would they do that. Why would a hole in
the ground surrounded by feathers get more bugs to fall
into it. It's not known, but Gomez suggests that maybe
it's something about the smell of the feathers, something about
the visual appearance. Maybe a quote he gives to the
Scientific American article, he says, just in general, soil insects
are quote very curious, So maybe putting an unusual item

around the entrance to the nest will just tend to
get wandering bugs to walk up to it and see
if it's something of use to them. But I think
this would not count just as baiting the way the
burrowing owl example would with the cow dung or the
bison dung, because in this case it's not just to

get the insects close to the nest. In this case,
the actual nest entrances, basically holes in the ground, function
quite well as pit traps because once the prey insect
falls in, they have difficulty climbing back out, and the
ants will rather quickly grab and butcher them. Now, this
is clearly not the only way this ant species has

to acquire prey. Fidolioxyops do lead the nest to acquire prey.
They forage like other ant species. But it's possible that
using the nest as a pit trap and surrounding it
with feathers as some kind of evolved behavior for luring
more insects into the hole that helps the colony supplement

their diet during especially times of the year, such as
the dry season in this region when prey is more scarce,
harder to come by.

Speaker 3 (53:25):
So they wouldn't be obligate trap builders. They would they
would be sort of they would have like a trap
business on the side. I guess you would say.

Speaker 1 (53:33):
Yes, if the trap interpretation is correct, it seems like
this would be a supplemental role in getting extra food
to them, extra diet diversity, especially in times when they're
they're going to be getting less in their foraging or
maybe when they're doing less foraging.

Speaker 3 (53:50):
Okay, yeah, because they're you know, again they're altering their
immediate environment anyway. There and then again, a whole like
this is not a huge energy investment.

Speaker 1 (54:05):
Is already part of the nest.

Speaker 3 (54:06):
Yeah, already part of the nest. I guess the question
is coming back to those those reasons that were put
forth earlier that we don't see more pit traps. Does
this would this make the the ant population more visible
to potential predators?

Speaker 1 (54:22):

Speaker 3 (54:22):
I mean maybe so, maybe not. Maybe maybe the animals
that would be interested in eating the ants already would
be able to detect their presence. And then again also
the ants have more capabilities than that one little larva
at the bottom of a small pit. You know, we're
not dealing with one organism. We're dealing with this, uh,
this entire colony of organisms that that kind of behave

as a single organism.

Speaker 1 (54:47):
Yeah, obviously I don't know what all the you know,
the cost benefit analysis of this evolutionary calculus would be.
But but yeah, there must be some reason why by
having your ant nest a as a pit trap and
this environment for this ant is is not such a
it's not such a danger that it outweighs the benefit

of getting some bugs to fall in as free meals.
But I also like this because it's like by house analogy.
It's like if your entire house was just like below
the ground and the entrance to the house was a
spike pit trap like a tiger trap. Yeah, just waited
for things to fall in and be like, oh bonus,
here's dinner, and you always and you had the lures,

you had the feathers all around. I don't know what
that would be in the human example, you put just
cotton candy around the around the trap that you come
in through.

Speaker 3 (55:40):
Well, this is certainly another fascinating example. Yeah, and I
love how both present the possibility of ants building traps.
But since they are ants, like it's it's not that
cut and dry, like, ants have a complexity all their own,
so you can't really look at them in the same
way that you would look at a single solitary spider
or certainly even you know, the human example, Like what

we do with traps and how we think about traps
is a rather different scenario compared to anything, you know,
anything that we're seeing in several of these animal examples.

Speaker 1 (56:11):
Yeah, well, I guess that does it for ant traps
on my end.

Speaker 3 (56:15):
But yeah, well this was fun. Who knows what the
future will hold. Perhaps there'll be more exciting studies coming
out of the world of ant research. I mean, it's
it's highly possible. I mean, we're still we're still making
significant discoveries about ant species and what they're up to.

Speaker 1 (56:32):
There are frontiers of ants you couldn't even dream of.

Speaker 3 (56:36):
There are ant traps that we don't even know about
yet because they haven't been sprung on us.

Speaker 1 (56:41):
When you fall into them. You go through the two
thousand and one stargate and in the room with the
French furniture.

Speaker 3 (56:52):
You know, we've never watched an ant movie for a
weird house cinema. I wonder if we should at some point.

Speaker 1 (56:57):
Oh, I have for years been looking at the cover
of a Blu ray at Videodrome called Phase four. It's
a picture of a hand with some ants. I know
it involves ants. I don't know anything else.

Speaker 3 (57:10):
I guess the question I would have, especially after talking
about ants like this again, is are we looking at
thinking about movies that have a giant ant in them
and have encounters with various giant ants, or is it
truly about the ants as this kind of super organism
And I like the latter.

Speaker 1 (57:29):

Speaker 3 (57:29):
Yeah, though, maybe having a giant sized ant is kind
of a way through our fantastic fiction that we think
about super organisms. So it's kind of like, yes, the
ants are small, but they work together and they're able
to do great things. So we just think of like
a giant ant. That's like just one way of contemplating
what they're capable of. So the next time ant movies

come back, if you're out there thinking about resurrecting the
giant ant movie, consider having them like tear people apart.
Things like that. You know, crawling out of windows, pulling
people taunt against the sides of a building and then
transferring them up to the rooftop and tearing them to pieces.

Speaker 1 (58:09):
Nice final processing.

Speaker 3 (58:11):
Yes, all right, well we're gonna gohe and close out
this episode here, but we'd love to hear from everybody
out there about traps, traps and movies, Traps in the
human world, traps in the animal world. Is there is
there some corner of this topic you'd like for us
to explore more in the future. Let us know we
would love to hear from you. If you would like
to listen to other episodes of Stuff to Blow Your Mind,

you will find them in the Stuff to Blow Your
Mind podcast feed Core episodes on Tuesdays and Thursdays, listener
mail on Monday's short form artifact on Wednesdays. On Friday,
we do Weird House Cinema. That's our time to set
aside most serious concerns and just look at a strange film.
As always, you can also get to us rather quickly
by going to Stuff to Blow your Mind dot com.

Speaker 1 (58:53):
Huge Things, So as always to our excellent audio producer
Seth Nicholas Johnson. If you would like to get in
touch with us with back on this episode or any other,
to suggest a topic for the future, just to say hello.
You can email us at contact and Stuff to Blow
Your Mind dot com.

Speaker 2 (59:15):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,
or wherever you're listening to your favorite shows.

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