Speaker 1: Hey, you welcome to Stuff to Blow your Mind. My
Speaker 1: name is Robert Lamb, and Hey, we were going to
Speaker 1: do our Hunters of the Dark Ocean Part two today,
Speaker 1: but Joe is outsick, so we're gonna come back in
Speaker 1: and continue that series on Tuesday. But don't worry, we
Speaker 1: should be back tomorrow with a brand new episode of
Speaker 1: Weird House Cinema. So instead we're going to go ahead
Speaker 1: and air the next Vault episode in the Life in
Speaker 1: the Hypogean World series. This is going to be part three.
Speaker 1: It originally published three twelve, twenty twenty four. Let's dive
Speaker 1: right in.
Speaker 2: Welcome to Stuff to Blow Your Mind, the production of iHeartRadio.
Speaker 1: Hey you welcome to Stuff to Blow your Mind. My
Speaker 1: name is Robert Lamb.
Speaker 3: And I m Joe McCormick, and we're back with part
Speaker 3: three of our series on cave biology and cave environments.
Speaker 3: Let's see what did we talk about in the last
Speaker 3: two episodes of the series. Obviously, if you haven't listened
Speaker 3: to those already, maybe you should go back and check
Speaker 3: those out first, But if you'd rather just jump in here,
Speaker 3: that's okay too. In the previous parts, we talked about
Speaker 3: some of the common characteristics of cave environments and especially
Speaker 3: in ways that would affect animal life. We talked about
Speaker 3: the presence of guano in some caves, bat dropping guano
Speaker 3: as sort of the base of a food chain, the
Speaker 3: equivalent of sunlight to the outside world to the inside
Speaker 3: of the cave. And we also talked about some specific
Speaker 3: cave organisms, such as the blind Mexican cavefish, about which
Speaker 3: there has been a lot of research research on how
Speaker 3: exactly these fish evolve. These various populations of fish in
Speaker 3: northeastern Mexican caves evolved to lose their sight and lose
Speaker 3: the pigment and their flight and so forth, Why that
Speaker 3: evolutionary pathway takes place in the cave environment and so forth.
Speaker 1: Yeah, so we're gonna so we've established to a degree,
Speaker 1: the cave environment, the cave ecosystem. We've talked about characteristics,
Speaker 1: We've talked about some individual species, and we're going to
Speaker 1: kind of continue that trend here. We're going to talk
Speaker 1: about some more specific organisms that make their homes in
Speaker 1: the cave environment, or we're going to look at creatures
Speaker 1: that dip into that ecosystem, dip into that biomass that
Speaker 1: is already living in the cave.
Speaker 3: All right, Well, I think I'm going to kick things
Speaker 3: off today with a full cave entry.
Speaker 1: All right, let's do it.
Speaker 3: No, no halfway in on this one.
Speaker 1: This is an obligate cave dweller.
Speaker 3: Right, So according to one source I was reading, actually
Speaker 3: this has been claimed as the first animal to be
Speaker 3: recognized as permanently adapted to a cave environment. I couldn't
Speaker 3: verify that priority, but that's the claim at least, so
Speaker 3: that may be true. This animal is an aquatic cave
Speaker 3: salamander called the oulm, also known as the proteus. Scientific
Speaker 3: name proteus. I think you would say Anguinus proteus a
Speaker 3: n g ui in us. The ulm occupies underground waterways
Speaker 3: in Europe, especially karst caves of the Dynaric Mountains, which
Speaker 3: is the region of the Balkans along the eastern coast
Speaker 3: of the Adriatic Sea, so you can think east of Italy,
Speaker 3: across the Adriatic from Italy. And I was looking around
Speaker 3: for some good sources on the history of human knowledge
Speaker 3: of this animal, because I know the first writings about
Speaker 3: it were very interesting. And I came across a paper
Speaker 3: in the Journal of Cave and Karste studies from twenty
Speaker 3: twenty one by Evo Lucic called an underworld tailored to tourists,
Speaker 3: a dragon, a photomodel, and a bioindicator. And Lucik does
Speaker 3: an interesting thing in this article. It's not really focused
Speaker 3: on biology. Instead, he's sort of focused on the history
Speaker 3: of how this animal has been perceived and categorized by
Speaker 3: the media and the public. So the earliest writings about
Speaker 3: the ulm are sort of famous. There is an account
Speaker 3: in the writing of a seventeenth century author and natural
Speaker 3: historian named Johann Weikard von Valvasor VLVASR. Valvasor, who was
Speaker 3: from the region then known as Carneola what is today Slovenia,
Speaker 3: and Valvasor famously published a sort of encyclopedia of the
Speaker 3: region known as the Glory of the Duchy of Carniola.
Speaker 3: And because of the striking geology of this region with
Speaker 3: the kar the caves, the work did contain some investigations
Speaker 3: of the local k Its caves, its associated culture and life.
Speaker 3: So here, summarizing Valvasor, Lucik says that around sixteen eighty nine,
Speaker 3: Valvasore reported that he had heard stories from peasants in
Speaker 3: a region known as the Vernica that they had seen
Speaker 3: a baby dragon in the local water source known as
Speaker 3: the Bayliss Spring, and the people who knew this spring
Speaker 3: said that the water would flow from it reliably twice
Speaker 3: a day, once around midnight and once again around nine am.
Speaker 3: And this apparently was linked to some kind of belief
Speaker 3: in an underground dragon, which, when it became angry, would
Speaker 3: spit out water and perhaps one of its own young
Speaker 3: One of the peasants that Valvasore spoke to said he
Speaker 3: had seen three young dragons spit up in this way
Speaker 3: by the spring, and a local mail carrier claimed that
Speaker 3: at one point he took one of the baby dragons
Speaker 3: home with him and it was about as big as
Speaker 3: his hand and looked like a lizard.
Speaker 1: And it does sort of look like a lizard, but
Speaker 1: I would say a little bit lizard, a little bit vampire, princess,
Speaker 1: little bit just you know, it depends what the lightings like.
Speaker 1: But yeah, it's this long, slender organism with this elongated
Speaker 1: head and these wonderfully dainty little limbs.
Speaker 3: Yeah, so it is a salamanderin form. It has a
Speaker 3: kind of flat, almost elongated I was gonna say shovel
Speaker 3: shaped head, but it's not really shovel shaped. It's more
Speaker 3: kind of if you look down from above, the head
Speaker 3: is sort of crocodile head shaped, but yeah, it is
Speaker 3: a kind of flat head. It has frilly red gills
Speaker 3: extending out from the base of its head around its neck.
Speaker 3: It has yeah, as you say, delicate little limbs that
Speaker 3: don't look like you know, they would do a whole lot,
Speaker 3: but it can use them. And otherwise the body is
Speaker 3: like a long kind of white snake. It is a translucent, white,
Speaker 3: fleshy skin going in this snakelike shape. I've heard some
Speaker 3: authors say that if you look at it closely, you
Speaker 3: can actually sort of see its organs through its skin,
Speaker 3: like they'll the light can sort of penetrate it and
Speaker 3: you can see its insides. And you can look up
Speaker 3: pictures of the ulm online. They're they're pretty readily accessible.
Speaker 3: It's it's a creepy looking organism. I mean, it does
Speaker 3: in some of these photos it almost seems to kind
Speaker 3: of glow because I guess of the maybe low light
Speaker 3: conditions in which it is being photographed, and it's very
Speaker 3: pale skin is like reflecting a lot of light.
Speaker 1: Yeah, I mean, I guess, kind of creepy, but also
Speaker 1: just haunting, almost kind of elfin in its in its appearance,
Speaker 1: you know, like this is a being from another world
Speaker 1: and it's its body and form, it's is entirely alien
Speaker 1: to us.
Speaker 3: And it's funny. So the rest of this paper by
Speaker 3: Lucik really emphasizes the extent to which sort of mythological
Speaker 3: themes have permeated the public understanding of this creature and
Speaker 3: are even in some ways still prevalent because of the
Speaker 3: ways that this creature is marketed by the local cave
Speaker 3: systems as tourist attraction, and those that marketing places a
Speaker 3: lot of emphasis on mythological themes, like referring to it
Speaker 3: as a dragon. However, of course, over the following generations
Speaker 3: after Valvasor, a scientific view of this creature began to
Speaker 3: take shape. That it was not a dragon, of course,
Speaker 3: but an amphibian, an amphibian that lived in waterways underneath
Speaker 3: the earth, which could explain why specimens were sometimes disgorged
Speaker 3: from a spring or cave opening after heavy rains. And
Speaker 3: so I wanted to get a scientific perspective on this creature,
Speaker 3: and I dug up a paper that I thought was interesting.
Speaker 3: This was a paper published in the Journal of Zoology
Speaker 3: in twenty twenty by belaws, Lwarn and Hertzcheg called extreme
Speaker 3: site fidelity of the oulm Proteus anguinus revealed by a
Speaker 3: long term capture mark recapture study. So I'm going to
Speaker 3: try to do a bit of a recap of what
Speaker 3: this paper does in reviewing some of the main biological
Speaker 3: characteristicks of this animal and then discuss the findings of
Speaker 3: their specific experiment. One thing they do, and this is
Speaker 3: important to do, I think in the episodes of this
Speaker 3: series is they remind us about the common characteristics of
Speaker 3: cave habitats. There can be some variation between different caves,
Speaker 3: but cave ecosystems are usually going to be shaped by
Speaker 3: a reduction or total absence of light that changes a
Speaker 3: lot about how organisms survive food scarcity. This is common
Speaker 3: to a lot of caves because, as you might recall
Speaker 3: other organisms we talked about, like the blind Mexican cavefish,
Speaker 3: seem to have adapted to their environment by having lower
Speaker 3: nutritional or energy needs than their surface surface variant cousins,
Speaker 3: that they need less food to survive, and they have
Speaker 3: to adapt to be this way. Because there's less food
Speaker 3: in a cave. Another thing the authors identify is what
Speaker 3: they call simplified communities. I looked this up to make
Speaker 3: sure I was understanding it right, So I found one
Speaker 3: other paper discussing this concept in the journal Bioscience, And
Speaker 3: according to their definition, simplification seems to be a quote
Speaker 3: reduction in niche diversity. So I think that means, you know,
Speaker 3: fewer ways for organisms to specialize, which kind of makes
Speaker 3: sense within a cave.
Speaker 1: Yeah.
Speaker 3: And then finally they mention that the cave environments are
Speaker 3: usually shaped by the fact that there the cave environment
Speaker 3: is a major buffer against changes in climate and other
Speaker 3: environmental variations. So living in a deep cave largely removes
Speaker 3: the variation of things like the night day cycle, seasonal
Speaker 3: changes to weather, and so forth. So a cave environment,
Speaker 3: though some changes can still come. And obviously if you're
Speaker 3: living in an underground waterway, like changes in water flow
Speaker 3: are possible, like heavy rains could still cause you know,
Speaker 3: increasing currents in the in the waterway and so forth.
Speaker 3: But there are going to be fewer cyclical, seasonal day, night,
Speaker 3: and other environmental changes in a cave than there are outside.
Speaker 1: You mean, of course, you also might want to throw
Speaker 1: in seasonal habitation by certain organisms such as bats or
Speaker 1: historically things like a cave bear. But even then, the
Speaker 1: deeper into the cave you get, you could potentially be
Speaker 1: even further removed from the influence of sad organisms.
Speaker 3: Right, And so the authors say, as several authors we've
Speaker 3: looked at have mentioned this, that the evolutionary ecology of
Speaker 3: caves is kind of hard to study for maybe obvious reasons,
Speaker 3: like aquatic caves especially are kind of hard to access,
Speaker 3: they require difficult diving and so forth. And they say
Speaker 3: that in the continent of Europe, vertebrates that are fully
Speaker 3: adapted to cave life are actually somewhat rare. There are
Speaker 3: more species that might go in and out of caves,
Speaker 3: but the ones that are the full on troglobions, the
Speaker 3: fully adapted to cave organisms, that there are not a
Speaker 3: whole lot of those. But one of the best known
Speaker 3: exceptions is the ome. It is not only a fully
Speaker 3: cave adapted organism, it is the largest cave dwelling vertebrate
Speaker 3: on Earth. The authors cite a couple of studies from
Speaker 3: Boulog in nineteen ninety four and Tronte in two thousand
Speaker 3: and seven to suggest that the ancestors of the OLM
Speaker 3: probably colonized caves somewhere between eight point eight and twenty
Speaker 3: million years ago. All known populations except for one, have
Speaker 3: regressed eyes and lack pigment in their bodies, so they
Speaker 3: appear eyeless and pale or translucent. The one accepted population
Speaker 3: is in a cave system in southeast Slovenia.
Speaker 1: There's one called the Black Ome. I remember running across
Speaker 1: and it stuck with me because that sounds like such
Speaker 1: a like a death metal olme. Yeah, in your European gaverns.
Speaker 3: But apparently just the difference is for some reason, this
Speaker 3: is the one population that has retained its pigment within
Speaker 3: the cave if they are top predators, which is kind
Speaker 3: of funny because when you look at them, they don't
Speaker 3: look like top predators. They look kind of unassuming, maybe creepy,
Speaker 3: but you know, they don't look scary. If that distinction
Speaker 3: makes sense.
Speaker 1: Yeah, I guess it comes down to again, how scary
Speaker 1: do you have to be in order to be the
Speaker 1: top predator in a cave ecosystem where again, you have
Speaker 1: you do have food chain, you do have a certain
Speaker 1: amount of biomass available, but it is, it's all niche,
Speaker 1: it's reduced, so you're not going to have these enormous organisms.
Speaker 1: You know, everything's going to be on a smaller, hungrier,
Speaker 1: and more versatile scale.
Speaker 3: Yeah, totally. And to be clear, I mean I'm not
Speaker 3: saying I actually think scariness is a biological indicator of
Speaker 3: whether you're a top predator or not. But you know,
Speaker 3: it's just the intuitions they don't seem to match. But
Speaker 3: they are the top predator in their cave environments. They
Speaker 3: prey on small animals like cave shrimp, snails, little insects,
Speaker 3: and they have no natural predators of their own, so
Speaker 3: there's nothing they have to normally watch out for preying
Speaker 3: on them there. They're the top of the pyramid because
Speaker 3: they have no predators. There's a part later in this
Speaker 3: paper where the authors observe that the olmuh do not
Speaker 3: seem to engage in hiding behaviors that they observed. At
Speaker 3: least they said it's possible that some olms are like
Speaker 3: hide back in cracks and crevices that they were never
Speaker 3: able to access on their dives, so you know, they
Speaker 3: couldn't locate them back there. But the ones they saw
Speaker 3: float out in the open, maintaining their place within the
Speaker 3: current of the cave waterway. Like you know, they're just
Speaker 3: not worried about that. They don't have to go hide.
Speaker 3: Now another way in which our naive intuitions about what
Speaker 3: it means to be a top predator can be violated.
Speaker 3: You might hear top predator and you think voracious appetite.
Speaker 3: You know, they're they're eating a lot, eating everything around them.
Speaker 1: No.
Speaker 3: Actually, the ome is famous for having an incredibly incredibly
Speaker 3: elastic energy needs. Like it it can survive five years
Speaker 3: apparently without food and can avoid starvation, so it can
Speaker 3: go into very low energy mode, can maintain a low metabolism,
Speaker 3: and can go for a long time without food.
Speaker 1: Yeah yeah, because again the reduced availability of prey and
Speaker 1: a given environment, you need to be able to really
Speaker 1: stretch out those the spaces between meal times.
Speaker 3: It's noted that they are neotonic, meaning they retain juvenile
Speaker 3: features into adulthood, and there's some other salamander species that
Speaker 3: do this as well. They can tolerate water with very
Speaker 3: little dissolved oxygen in it, so they have low food
Speaker 3: energy needs and low oxygen needs. And while they are
Speaker 3: blind to light. They do have a number of compensating
Speaker 3: sense mechanisms. The authors mention one of them is what's
Speaker 3: known as raotaxis. Raeotaxis is the ability to sense the
Speaker 3: direction of flow within the water, and then that's also
Speaker 3: paired with a behavioral instinct that causes the salamander to
Speaker 3: turn to orient its body facing into the water flow.
Speaker 3: And this is a common way for fish and other
Speaker 3: aquatic organisms to remain stationary rather than drifting away with
Speaker 3: water currents. They also use other senses than site. They
Speaker 3: have underwater hearing, they use their sense of smell or
Speaker 3: old faction, and they appear to have a magnetic sensoryability
Speaker 3: as well, which may help them orient with respect to
Speaker 3: Earth's magnetic field, possibly useful for orientation and navigation. As
Speaker 3: I said, the ulme has very restricted food needs like
Speaker 3: some other troglobiants we've discussed. You remember the blind Mexican
Speaker 3: cave fish had very low food needs compared to its
Speaker 3: surface variant cousin. They have what the authors call extreme
Speaker 3: life history adaptations, meaning their life just appears to sort
Speaker 3: of go in slow motion compared to salamanders you might
Speaker 3: on the surface. So I was looking up the maximum
Speaker 3: life span of surface amphibians, and of course that varies,
Speaker 3: but you know, on average it's going to be more
Speaker 3: in the range of ten to twenty years for large
Speaker 3: amphibians that live on the surface. The olem is thought
Speaker 3: to live for one hundred years or more, with females
Speaker 3: only reproducing once every twelve and a half years roughly,
Speaker 3: So that is incredibly long life for an amphibian, incredibly
Speaker 3: long in between mating and reproduction. So this experiment tried
Speaker 3: to study the behavior of the olm, especially the movement
Speaker 3: and migratory patterns of the olm, by using a capture,
Speaker 3: mark and recapture method, so you know, they'd catch one,
Speaker 3: they'd market, and then they would come back and see
Speaker 3: if they could capture the same ones again later note
Speaker 3: where they were relative to the original capture and so forth. Specifically,
Speaker 3: they were studying an eastern Herzegovinian population and the authors
Speaker 3: found what they called extra sdream site fidelity. Most of
Speaker 3: the creatures that they captured had barely moved since the
Speaker 3: years before. The average distance was about five meters from
Speaker 3: the original capture location a year before, and they also
Speaker 3: did multiple interval studies, so like capturing them at different times,
Speaker 3: and then checking up on them again. They found that
Speaker 3: moving distance was not correlated with the time since capture.
Speaker 3: So for a lot of species you might expect that
Speaker 3: the longer you go in between captures, the farther away
Speaker 3: from their original location they might have moved. In these salamanders,
Speaker 3: not the case. The longer you go in between captures
Speaker 3: it does not, on average affect how far away they
Speaker 3: are from the first time. So the question is why
Speaker 3: do they move so little? There could be a number
Speaker 3: of answers here, and the authors say, to be fair
Speaker 3: extreme site fidelity the extreme site fidelity of these salamanders
Speaker 3: is not necessarily extreme among amphibians. There are also some
Speaker 3: surface amphibians that may have very limited movement ranges. The
Speaker 3: authors could not find any reason based on the environment
Speaker 3: itself that would limit movement. In other words, there were
Speaker 3: no like gaps in the movement patterns that would indicate
Speaker 3: environmental features they were trying to avoid, and so they
Speaker 3: say their best guess is that this hyper sedentary lifestyle
Speaker 3: is probably related to energy constraints. The author's right quote,
Speaker 3: We can only speculate that animals feeding on a very
Speaker 3: low food supply and as consequence resistant to starvation, reproducing sporadically. Again,
Speaker 3: females reproducing on average only once in twelve point five
Speaker 3: years and living for a century, are very energy cautious
Speaker 3: and limit their movements to the minimum. It's a different
Speaker 3: kind of animal life to imagine, isn't it like an
Speaker 3: animal that to be clear, it's not incapable of moving quickly,
Speaker 3: like if you try to capture one and it has
Speaker 3: to perform orm an evasive maneuver essentially like it's trying
Speaker 3: to get away from you. They can move quickly. It
Speaker 3: just seems like undisturbed in their natural environment. If you
Speaker 3: use the capture recapture method, they haven't moved much after
Speaker 3: a year, after two years, and so on.
Speaker 1: Wow.
Speaker 3: The author is also note I thought this was interesting
Speaker 3: that I don't know exactly what to make of it,
Speaker 3: But they say that they have never seen a dead individual.
Speaker 3: Kind of interesting.
Speaker 1: H Yeah. I mean, obviously we're dealing with creatures that are,
Speaker 1: like we said, difficult to observe anyway, and you know,
Speaker 1: we can't count out various other organisms that would then
Speaker 1: scavenge a dead one. We also have to take into account,
Speaker 1: you know, the movements of the waters that have at
Speaker 1: least historically been attributed to ones occasionally washing out and
Speaker 1: so forth. And even if one didn't wash out all
Speaker 1: the way to where humans could have observed them, it
Speaker 1: might wash them out to where other organisms would have
Speaker 1: a shot at scavenging them. But still it's an interesting
Speaker 1: tid bit.
Speaker 3: Yeah, yeah, yeah. To be clear, I don't think they
Speaker 3: meant like humans have never observed a dead one obviously.
Speaker 3: I think they mean like in the in the region
Speaker 3: where they're looking at the live ones, they've never seen
Speaker 3: a dead one there, right right, yeah.
Speaker 1: Yeah, And like I said, that could be because it
Speaker 1: is they do get periodically fleshed out I'm guessing, or yeah,
Speaker 1: scavengers of one sort or another.
Speaker 3: The author is add a conservation note in their paper,
Speaker 3: which is that the extreme site fidelity of the of
Speaker 3: the olm makes it quite vulnerable to water pollution. You know,
Speaker 3: it changes to water quality, especially like if it can't
Speaker 3: I think, if it can't really migrate very effectively to
Speaker 3: get to a place where there's better water, it's more
Speaker 3: vulnerable to changes in water quality locally.
Speaker 1: Though.
Speaker 3: Vulnerability to water pollution I think is also true of
Speaker 3: many surface amphibians who are especially vulnerable because of the
Speaker 3: permeability of their skin. So yeah, another reason why, I
Speaker 3: mean not like we needed that many more reasons why
Speaker 3: water pollution is a bad thing. But here's another one.
Speaker 3: But final note, if you haven't seen a picture of
Speaker 3: the olm, you should look this one up. You want
Speaker 3: to see this flesh.
Speaker 1: Oh yeah, absolutely, it's a.
Speaker 3: Very it's a very Cronenberg biodesign.
Speaker 1: Yeah, they're like I say, they're a little creepy, a
Speaker 1: little cute. They're very unique. All right. I want to
Speaker 1: get into a topic here that that came up early
Speaker 1: on in my research and a paper that came up
Speaker 1: pretty early on in researching these episodes, and it has
Speaker 1: to do with intraguilled predation. That's the killing and eating
Speaker 1: of potential competitors within an ecosystem, which is apparently a
Speaker 1: pretty big deal in the food chain of the Hypogean world. So,
Speaker 1: as we discussed in previous episodes and specifically in the
Speaker 1: last episode, you know, bat guano is kind of an
Speaker 1: alternative sunlight that forms sort of the base of the
Speaker 1: subtrain in Easystem a lot of the times as bats
Speaker 1: roost in the cave and defecate, thus bringing new resources
Speaker 1: for various organisms to feed on, which in turn feed
Speaker 1: other consumers. And as discussed in a twenty twenty one
Speaker 1: paper published in Scientific Reports by Param Mutchova at all quote,
Speaker 1: the food web in a subterranean ecosystem is driven by
Speaker 1: intragild predation. So in this paper they drive home some
Speaker 1: of what we discussed last time. That quote. Detritus based
Speaker 1: food webs are prevalent in cave systems, though you do
Speaker 1: have cases where again sunlight enters cavern openings or through
Speaker 1: other fissures, and also have situations where some manner of
Speaker 1: chemo autotrophy is taking place. But still you know, it
Speaker 1: often falls to bat guano as well as other transportation
Speaker 1: networks for dead plants and to tried us such as
Speaker 1: via gravitation, pawn or streams. It's like a steep sinkhole
Speaker 1: situation percating water. And also animal cadavers, the animal cadaver
Speaker 1: being something that is you know, the animal has gone
Speaker 1: in there and died or something has brought the animal
Speaker 1: couldaver into the cave generally.
Speaker 3: So that's a good list. So as you said, there
Speaker 3: are places where the sunlight gets in. Chemo autotrophy would
Speaker 3: be an alternative to photo autotrophy. You know, mostly we're
Speaker 3: on the on the surface, the autotrophs are making energy
Speaker 3: out of sunlight, but it can also be done with
Speaker 3: certain types of chemicals in the darkness. And then as
Speaker 3: you said, bat iguano, and then just basically various ways
Speaker 3: for stuff to fall into the cave or be brought
Speaker 3: into the cave that could.
Speaker 1: Be eaten, yeah, falling in and potentially flowing in in
Speaker 1: the same way that a dead olme might flow out
Speaker 1: of a cave, if we're to take that earlier accounted
Speaker 1: face value. So anyway, that's the base, you know, and
Speaker 1: you have all of these consumer interactions atop of all
Speaker 1: that in a cave. And this particular study examined the
Speaker 1: subterranean ecosystem of the Autovaska Cave and Slovakia. The predators
Speaker 1: they examined were all arthropods living in the cave, including
Speaker 1: a species of might a beetle, two different spiders, and
Speaker 1: a couple of other species, and they were able to
Speaker 1: examine DNA in the guts of each species to see
Speaker 1: what they were eating. As expected, they found a complex
Speaker 1: system of intragil prediction, again killing and eating of potential competitors,
Speaker 1: and they included a handy visual guy that I really liked,
Speaker 1: so I included it here for you to look at, Joe.
Speaker 1: They have essentially five dots scored here on the illustration,
Speaker 1: each one representing one of these five species they looked at,
Speaker 1: and then each one is color coded with color coded
Speaker 1: lines indicating which one feeds on which, and you end
Speaker 1: up with this complex almost pretty much a star pattern,
Speaker 1: but with a few more lines on some connections, and
Speaker 1: sometimes there's not a line connecting ones species to another.
Speaker 3: It looks like almost all of them are eating each other.
Speaker 3: There's one that's really eating everybody and almost and all
Speaker 3: the others are eating at least two other ones.
Speaker 1: Right right. And then you know they acknowledge their limitations
Speaker 1: and their study and so forth, so it's not this
Speaker 1: is not necessarily all that ever happens between these these species,
Speaker 1: but this is what they're they're got syndicated when they
Speaker 1: were studied, and so they stress that integill predation is
Speaker 1: often important in nitrogen poor diets, as is cannibalism, which
Speaker 1: that which they found evidence of, and it should be
Speaker 1: stressed that scavenging may be part of both cases. So
Speaker 1: you know, on one hand, you have like straight up
Speaker 1: predation like well there's my competitor, I've got the drop
Speaker 1: on them. I shall eat them, but also a situation
Speaker 1: of well there is my competitor, they have died.
Speaker 3: What you're going to do right, Yeah, because often in
Speaker 3: energy relationships like this, trying to prey on a healthy
Speaker 3: adult of like a of a competitor within the food
Speaker 3: chain is usually going to be kind of dangerous. So
Speaker 3: I think we've read about integuild predation before, some of
Speaker 3: it being not predation but scavenging, but other ones being
Speaker 3: like adults of one species preying on the young of
Speaker 3: the other.
Speaker 1: Yeah, because you know, otherwise, going toe to toe with
Speaker 1: someone or something in the ecosystem that is your equal, like,
Speaker 1: that's that's a gamble and survival is on the line
Speaker 1: regardless if you engage in that struggle, And you might
Speaker 1: only engage in that struggle if survival is already on
Speaker 1: the line. And yeah, it would seem in the impoverished
Speaker 1: food web of the dark, you get what you get.
Speaker 1: You don't pitch a fit. Each of the species here
Speaker 1: that they looked at consumed a wide variety of prey
Speaker 1: and indulged in integral predations as presumably necessary. So it
Speaker 1: would seem based on what reading here that Yeah, while
Speaker 1: you know, integral predation of course, as you said, occurs
Speaker 1: in the sunlit world as well and in the oceans
Speaker 1: and so forth, within the cave environment, it might be
Speaker 1: more pronounced again due to the limited scope of the
Speaker 1: available biomass, available nutrients and so forth.
Speaker 3: Right, Yeah, I mean the fact that it's a place
Speaker 3: where food is scarce creates weird biological incentives and emphasies.
Speaker 1: Yeah. So so, yeah, I thought this was very interesting.
Speaker 1: But I want to get into this other area here
Speaker 1: for the remainder of the episode here, having to do
Speaker 1: with outsiders in the cave, creatures who have come into
Speaker 1: the cave to take advantage of what is there. Because
Speaker 1: once again there's the there, there's the idea that the
Speaker 1: cave environment comes with pros and cons. One cons, as
Speaker 1: we've discussed already, is that the food chain here is
Speaker 1: just less robust, specialized obligate cave organisms generally have carved
Speaker 1: out a very narrow niche in which to live. A
Speaker 1: big pro, however, is, as with the OLM, you're often
Speaker 1: dealing with fewer predators and a more secluded life mm hmm.
Speaker 1: It's like the Phantom of the Opera. You know, you
Speaker 1: have this vast catacomb empire over which to rule and
Speaker 1: row your boat around, and you have great acoustics, you know,
Speaker 1: for your singing, for your your your cool pipe organ.
Speaker 1: But the real music scene is upstairs in the sunlit world,
Speaker 1: and you are, you know, to a large extent cut
Speaker 1: off from that.
Speaker 3: You really need to kidnap a singer from up there
Speaker 3: to make your songs work better down there.
Speaker 1: Yeah, yeah, so there there is a potential advantage here
Speaker 1: for creatures of both worlds and creatures of the surface
Speaker 1: that have figured out how and when to venture indicates
Speaker 1: to take advantage of the creatures that live there, at
Speaker 1: least live there periodically. And you know, I don't think
Speaker 1: we've run across anything that's going in to harvest the olms.
Speaker 1: But as we've been discussing, one of the most abundant
Speaker 1: life forms you might pray or scavenge upon the in
Speaker 1: caverns are creatures that spend part of their time there
Speaker 1: as well. That being bats, they roost in great numbers.
Speaker 1: They enjoy a great deal of security there. But a
Speaker 1: specialist could get in there and reap the bounties.
Speaker 3: Oh, I don't know if I ever thought about that,
Speaker 3: So what would do that?
Speaker 1: Well, a number of organisms. Actually, I was looking at
Speaker 1: a paper from nineteen seventy two. This is by Winkler
Speaker 1: and Atoms titled Utilization of Southwestern Bat Caves by Terrestrial Carnivores,
Speaker 1: and this is published in the Journal of the American
Speaker 1: Middland Naturalist. And they point out that various predators venture
Speaker 1: into caves to enjoy the occasional bat feast, either via
Speaker 1: active hunting or by scavenging for fallen bats. And this
Speaker 1: includes broadly like various reptiles, raptorial birds, and mammals. For instance,
Speaker 1: they point out that at Braw Cave, raccoons and some
Speaker 1: skunks were observed to venture into the cave to prey
Speaker 1: on fallen bats at the cave mouth. Because you know,
Speaker 1: I think we discussed this at least in Passing earlier.
Speaker 1: You have large populations of bats residing in many of
Speaker 1: these caves, and occasionally bats do fall be they you know,
Speaker 1: young bats, older bats, in firm bats, et cetera. They're
Speaker 1: just too many of them this for this not to happen.
Speaker 1: It will occasionally rain a little bit of food in
Speaker 1: the form of a bat and an organism that is
Speaker 1: operate into tunistic enough can get in there and collect
Speaker 1: those and eat them, or you know, eat them before
Speaker 1: they're able to crawl across the cave floor and then
Speaker 1: back up the walls to enjoy their roost again.
Speaker 3: So the cave buffet underneath the bat roost is mostly guano,
Speaker 3: but occasionally bat meat as well.
Speaker 1: That's right. So ringtail cats were observed at another cave,
Speaker 1: but it's aimed as if, especially at Brackencave, raccoons were
Speaker 1: the most likely to take advantage of the bat bounty
Speaker 1: during both the day and the night. And and you
Speaker 1: know this, this makes sense concerning the raccoon because as
Speaker 1: we've talked about in the show before, you know, they're
Speaker 1: they're great opportunists. Uh they are. They're nocturnal omnivores and
Speaker 1: they have exceedingly wise pause.
Speaker 3: Oh that's right. I'm just now recalling that we did
Speaker 3: an episode a while back about their apparent their strange
Speaker 3: apparent washing of food behavior and the question about like
Speaker 3: whether that really is washing or some other type of
Speaker 3: behavioral instinct. And oh, I can't remember off the top
Speaker 3: of my head what episode that was in But I
Speaker 3: remember that that that one really got my mind.
Speaker 1: Going, Yeah, I remember talking about like, for instance, they
Speaker 1: are they're they're great opportunistic organisms that can adapt to
Speaker 1: various environments, so they've done quite well with urban environments.
Speaker 1: Uh and uh and yeah. We also discussed the heartbreaking
Speaker 1: video foot that you can look up online of a
Speaker 1: raccoon attempting to to dunk. It's uh it's a plunder
Speaker 1: of cotton candy into the water and then seemingly confused
Speaker 1: as it draws the bounty back out of the water
Speaker 1: and finds that it is no longer uh there for it.
Speaker 1: It's again kind of heartbreaking to watch.
Speaker 3: Yeah, totally, I just looked it up. By the way,
Speaker 3: it was in our series on animals, quote cooking things
Speaker 3: on the cuisine and kitchen behavior is observed in animals,
Speaker 3: including the apparent washing of food. But again, I think
Speaker 3: there was a question of whether that's really what raccoons
Speaker 3: are doing or not.
Speaker 1: Yeah, but they're they're they're they're little paws, they are
Speaker 1: little hands. If you will are are are excellent. I've
Speaker 1: I've seen it described that they can essentially see you
Speaker 1: with their hands in ways that we could maybe relate
Speaker 1: to on some level, but as is often the case
Speaker 1: with the sense worlds of animals, of non human animals,
Speaker 1: we generally can't fully image what it's like like they
Speaker 1: they can see with their hands is the best way
Speaker 1: that we can perhaps understand it.
Speaker 3: Yeah, yeah, that was one of the hypotheses. It was
Speaker 3: like that the water somehow hypercharges the sensitivity of the
Speaker 3: hands and sensing the food. Yeah.
Speaker 1: Yeah. Now this cave in question, Bracken Cave, This is
Speaker 1: a Texas cave outside of San Antonio that is home
Speaker 1: to the largest known bat colony in the world. Some
Speaker 1: twenty million Mexican freetail bats roost here between March and October.
Speaker 1: This also apparently makes it the largest known concentration of
Speaker 1: mammals period, including humans. I'm assuming, and I imagine this
Speaker 1: takes into account the size of the cave and the
Speaker 1: estimates and estimated concentration of bats as compared to human cities.
Speaker 1: But even among human cities, they're only something like six
Speaker 1: cities with populations of more than twenty million, So we're
Speaker 1: talking a lot of bats. And I didn't run, I
Speaker 1: didn't look up or do the math on this, but
Speaker 1: you know, you think about twenty million bats, how many
Speaker 1: bats are going to potentially fall So that does create
Speaker 1: a certain opportunity for animals that are willing to get
Speaker 1: in there day or night and pick them off before
Speaker 1: they can get back up to the top.
Speaker 3: Yeah, with twenty million bats, I mean, even if you
Speaker 3: assume a low death rate, that's got to be thousands
Speaker 3: falling into the floor all the time.
Speaker 1: Yeah. Now, reptiles also get on the action as well,
Speaker 1: as that paper indicated, And one of the more alarming examples,
Speaker 1: I don't know, it could be alarming, depends on what
Speaker 1: you think about snakes is the example of yellow red
Speaker 1: rat snakes found in a cave in Mexico that is
Speaker 1: sometimes referred to as the Cave of Hanging Snakes.
Speaker 3: Hanging snakes.
Speaker 1: Yes, so the yellow red rat snake is endemic to
Speaker 1: Mexico and Central America, so it's fairly widespread. It's non venomous.
Speaker 1: It prays mostly on rodents and birds and lizards, but
Speaker 1: also on the menu are bats. So the Mexican cave
Speaker 1: in question is Cantemo Cave in the Mexican state of
Speaker 1: kintani Roo, about one hundred and eighty miles from Cancun,
Speaker 1: known locally, just as the bat cave. According to Jose
Speaker 1: Maria Morells, writing for Atlas Obscura, the snakes here have
Speaker 1: developed an amazing method of eating those bats that doesn't
Speaker 1: involve picking them off on the cave floor. So what
Speaker 1: they do, apparently, is they crawl up into the cracks
Speaker 1: in the ceiling of the cave as well as high
Speaker 1: up on the cave walls. And then when the bats,
Speaker 1: you know, the bats are roosting in there, so they
Speaker 1: leave and then they come back. They leave to feed,
Speaker 1: and then they come back. And when they're doing this,
Speaker 1: when they're going in or out of the cave, that
Speaker 1: is when the snakes will either dangle down or otherwise
Speaker 1: like lash out to catch a passing bat in its mouth. Wow.
Speaker 1: And I've included a couple of photos here for you
Speaker 1: to look at, Joe, one of the snake grabbing having
Speaker 1: grabbed a bat and it's like, you know, just swallowing it.
Speaker 1: And then there's another one of the snake up in
Speaker 1: the recesses. This is these are actually, these are excellent photos.
Speaker 1: They're from a Newsweek article that put that that profiled
Speaker 1: these snakes.
Speaker 3: That is crazy. Now, I had a question that I
Speaker 3: think I may have partially answered, but I just looked
Speaker 3: up more images of these snakes jumping out to snag bats,
Speaker 3: and my question was, well, how do they have the
Speaker 3: leverage to do that? Because I was imagining them just
Speaker 3: sort of like crawling up a cave wall. But in
Speaker 3: some of the pictures I'm looking at, they have found
Speaker 3: like a they're in like a recess, like a cubby
Speaker 3: hole in the wall, and so I think they're gripping
Speaker 3: something back there with the back half of their body
Speaker 3: where they while they lunge out with the front half
Speaker 3: to to grab a bat.
Speaker 1: Now you mentioned looking up images of this, Yeah, there
Speaker 1: there are a lot of images of these of these snakes.
Speaker 1: There's some footage as well. This cave has become an
Speaker 1: ecotourism destination, so a lot of people have gotten to
Speaker 1: go there. It's been covered in by a lot of
Speaker 1: news outlets, various documentaries. So you can definitely see some
Speaker 1: images of these snakes either you know, dangling from the
Speaker 1: ceiling or consuming the bats that they have acquired.
Speaker 3: Wow, that's one of those behaviors where it's like I
Speaker 3: would love an evolutionary account of how that arises, if
Speaker 3: that's known or if there's something suspected, like how long
Speaker 3: have these snakes specialized in attacking bats this way? And
Speaker 3: like what were they doing before that?
Speaker 1: Yeah? Yeah, I mean I guess it's kind of a
Speaker 1: natural extrapolation of surface world environments, especially I'm thinking our
Speaker 1: boreal environments. Right. The cave is just like a novel
Speaker 1: form of that. And with the bat population, you have
Speaker 1: just such a concentration of potential prey. You're going to
Speaker 1: have organisms that are drawn to it and ones that
Speaker 1: are able to adapt their existing practices. They're existing predation
Speaker 1: and scavenging practices to it, or as with the raccoon,
Speaker 1: are just generally great opportunists. You know, they're going to
Speaker 1: be able to help reap some of that bounty for themselves.
Speaker 3: Well, Rob, thank you for introducing me to these hanging snakes.
Speaker 3: I didn't know they existed, and now I love them.
Speaker 3: So I think we probably have to call it there
Speaker 3: for part three of our series on cave biology, but
Speaker 3: I think we're going to be back for one more.
Speaker 3: Three was not enough. There will be one more episode.
Speaker 1: I think, So I think a fourth episode will wrap
Speaker 1: it up for this journey into the caves, But you know,
Speaker 1: after that we'll probably be back in the future at
Speaker 1: some point or another. Caves and their ecosystems and human
Speaker 1: traditions associated with them are just too fascinating, all right.
Speaker 1: In the meantime, we're going to go ahead and remind
Speaker 1: everybody that's stuff to blow your mind. Is primarily a
Speaker 1: science and culture podcast that publishes new core episodes on
Speaker 1: Tuesdays and Thursdays, sandwiched in between there on Wednesdays there's
Speaker 1: a short form episode for you Monster Fact Artifact or
Speaker 1: Animalia stipendium. On Mondays we do listener mail, and then
Speaker 1: on Fridays we set aside most serious concerns to just
Speaker 1: talk about a weird film on Weird House Cinema. Usually
Speaker 1: those are self contained single episodes, but if you're just
Speaker 1: tuning into our channel for the first time, this week,
Speaker 1: we are covering David Lynch's nineteen eighty four adaptation of
Speaker 1: Dune in two parts, because it is that weird that
Speaker 1: packed with talent, and also, you know, Dune is in
Speaker 1: the air right now, the spice is in the air,
Speaker 1: and we have to acknowledge that.
Speaker 3: Cool wahad huge thanks as always to our excellent audio
Speaker 3: producer JJ Posway. If you would like to get in
Speaker 3: touch with us with feedback on this episode or any other,
Speaker 3: to suggest a topic for the future, or just to
Speaker 3: say hello. You can email us at contact at stuff
Speaker 3: to Blow your Mind dot com.
Speaker 2: Stuff to Blow Your Mind is production of iHeartRadio. For
Speaker 2: more podcasts from my heart Radio's the iHeartRadio app, Apple Podcasts,
Speaker 2: or wherever you're listening to your favorite shows.