Speaker 1: Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 2: Hey you welcome to Stuff to Blow Your Mind. My
Speaker 2: name is Robert Lamb.
Speaker 3: And I am 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 organism, 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 in their flesh and so forth. Why that
Speaker 3: evolutionary pathway takes place in the cave environment and so forth.
Speaker 2: Yeah, so we're so we've established to a degree, the
Speaker 2: cave environment, the cave ecosystem. We've talked about characteristics, We've
Speaker 2: talked about some individual species, and we're going to kind
Speaker 2: of continue that trend here. We're going to talk about
Speaker 2: some more specific organisms that make their homes in the
Speaker 2: cave environment, or we're going to look at creatures that
Speaker 2: dip into that ecosystem, dip into that biomass that is
Speaker 2: 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 2: All right, let's do it.
Speaker 3: No, no halfway on this one.
Speaker 2: 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 oulm occupies underground waterways
Speaker 3: in Europe, especially Kars 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 Karst Studies from twenty
Speaker 3: twenty one by Evo Lucik 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 sting geology of this region with
Speaker 3: the kars the caves, the work did contain some investigations
Speaker 3: of the local its caves, its associated culture and life.
Speaker 3: So Here, summarizing Valvasor, Lucik says that around sixteen eighty nine,
Speaker 3: Valvasour 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 male care 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 2: And it does sort of look like a lizard, but
Speaker 2: I would say a little bit lizard, a little bit
Speaker 2: vampire princess, a little bit just you know, it depends
Speaker 2: what the lightings like. But yeah, it's this long, slender
Speaker 2: organism with this elongated 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 the 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: that like 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 its very
Speaker 3: pale skin is like reflecting a lot of light.
Speaker 2: Yeah, I mean, I guess, kind of creepy, but also
Speaker 2: just haunting, almost kind of elfin in its in its appearance,
Speaker 2: you know, like this is a being from another world
Speaker 2: and it's its body and form, it's is entirely alien
Speaker 2: to us.
Speaker 3: And it's funny. So the rest of this paper by
Speaker 3: Lucik really emphasizes the to which sort of mythological themes
Speaker 3: have permeated the public understanding of this creature and are
Speaker 3: even in some ways still prevalent because of the ways
Speaker 3: that this creature is marketed by the local cave systems
Speaker 3: as a 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, l, Warn and Hurts called
Speaker 3: extreme site fidelity of the oulm Proteus anguinus revealed by
Speaker 3: a long term capture mark recapture study. So I'm going
Speaker 3: to try to do a bit of a recap of
Speaker 3: what this paper does in reviewing some of the main
Speaker 3: biological characteristics of this animal and then discuss the findings
Speaker 3: of their specific experiment. One thing they do, and this
Speaker 3: is important to do, I think in the episodes of
Speaker 3: this series is they remind us about the common characteristics
Speaker 3: of 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. And then finally they mention that
Speaker 3: the cave environments are usually shaped by the fact that
Speaker 3: there the cave environment is a major buffer against changes
Speaker 3: in climate and other environmental variations. So living in a
Speaker 3: deep cave largely removes the variation of things like the
Speaker 3: night day cycle, seasonal changes to weather, and so forth.
Speaker 3: So a cave environment, though some changes can still come.
Speaker 3: And obviously if you're living in an under ground waterway,
Speaker 3: like changes in water flow are possible, like heavy rains
Speaker 3: could still cause you know, increasing currents in the in
Speaker 3: the waterway and so forth. But there are going to
Speaker 3: be fewer cyclical, seasonal day, night, and other environmental changes
Speaker 3: in a cave than there are outside.
Speaker 2: You mean, of course, you also might want to throw
Speaker 2: in seasonal habitation by certain organisms such as bats or
Speaker 2: historically things like a cave bear. But even then, the
Speaker 2: deeper into the cave you get, you could potentially be
Speaker 2: even further removed from the influence of sad.
Speaker 3: Organisms, right, And so the authors say, as several authors
Speaker 3: we've looked at have mentioned this, that the evolutionary ecology
Speaker 3: of caves is kind of hard to study for maybe
Speaker 3: obvious reasons, like aquatic caves especially are kind of hard
Speaker 3: to access, they require difficult diving and so forth. And
Speaker 3: they say that in the continent of Europe, vertebrates that
Speaker 3: are fully adapted to cave life are actually somewhat rare.
Speaker 3: There are more species that might go in and out
Speaker 3: of caves, but the ones that are the full on troglobions,
Speaker 3: the fully adapted to cave organisms that there are not
Speaker 3: a whole lot of those. But one of the best
Speaker 3: known exceptions is the ome. It is not only a
Speaker 3: fully cave adapted organism, it is the largest cave dwelling
Speaker 3: vertebrate on Earth. The authors cite a couple of studies
Speaker 3: from boulog in nineteen ninety four and Tronte in two
Speaker 3: thousand and seven to suggest that the ancestors of the
Speaker 3: OLM probably colonized caves somewhere between eight point eight and
Speaker 3: twenty million years ago. All known populations except for one,
Speaker 3: have regressed eyes and lack pigment in their bodies, so
Speaker 3: they appear eyeless and pale or translucent. The one accepted
Speaker 3: population is in a cave system in southeast Slovenia.
Speaker 2: There's one called the black Ole. I remember running across,
Speaker 2: and it stuck with me because that sounds like such
Speaker 2: a like a death metal home in your European caverns.
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 caves. They are top predators, which is kind of
Speaker 3: funny because when you look at them, they don't look
Speaker 3: 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 2: Yeah, I guess it comes down to again, how scary
Speaker 2: do you have to be in order to be the
Speaker 2: top predator in a cave ecosystem where again, you have
Speaker 2: you do have food chain, you do have a certain
Speaker 2: amount of biomass available, but it is it is, it's
Speaker 2: all nache. It's reduced, so you're not going to have
Speaker 2: these enormous organisms. You know, everything's going to be on
Speaker 2: a smaller, hungrier, 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. They're the top of the pyramid because they
Speaker 3: have no predators. There's a part later in this paper
Speaker 3: where the authors observe that the olm do not seem
Speaker 3: to engage in hiding behaviors that they observed. At least
Speaker 3: they said, it's possible that some olms are like hide
Speaker 3: back in cracks and crevices that they were never able
Speaker 3: to access on their dives, so you know, they couldn't
Speaker 3: locate them back there. But the ones they saw float
Speaker 3: out in the open, maintaining their place within the current
Speaker 3: of the cave waterway, Like you know, they're just not
Speaker 3: worried about that. They don't have to go hide. Now,
Speaker 3: another way in which our naive intuitions about what it
Speaker 3: means to be a top predator and be violated. You
Speaker 3: might hear top predator and you think voracious appetite. You know,
Speaker 3: they're eating a lot, eating everything around them. No, Actually,
Speaker 3: the ole is famous for having an incredibly incredibly elastic
Speaker 3: energy needs, Like it can survive years apparently without food
Speaker 3: and can avoid starvation, so it can go into very
Speaker 3: low energy mode, can maintain a low metabolism and can
Speaker 3: go for a long time without food.
Speaker 2: Yeah, yeah, because again the reduced availability of prey and
Speaker 2: a given environment, you need to be able to really
Speaker 2: 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 raeotaxis. 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 oldfaction,
Speaker 3: and they appear to have a magnetic sensoryability as well,
Speaker 3: which may help them orient with respect to Earth's magnetic field,
Speaker 3: possibly useful for orientation and navigation. As I said, the
Speaker 3: ulm has very restricted food needs like some other troglobiants
Speaker 3: we've discussed. You remember the blind Mexican cave fish had
Speaker 3: very low food needs compared to its surface variant cousin.
Speaker 3: They have what the authors call extreme life history adaptations,
Speaker 3: meaning their life just appears to sort of sort of
Speaker 3: go in slow motion compared to salamanders you might find
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 catch one,
Speaker 3: they mark it, and then they would come back and
Speaker 3: see if they could capture the same ones again later,
Speaker 3: note where they were relative to the original capture and
Speaker 3: so forth. Specifically, they were studying an eastern Herzegovinian population
Speaker 3: and the authors found what they called extreme site fidelity.
Speaker 3: Most of the creatures that they captured had barely moved
Speaker 3: since the years before. The average distance was about five
Speaker 3: meters from the original capture location a year before. And
Speaker 3: they also did multiple interval studies, so like capturing them
Speaker 3: at different times and then checking up on them again.
Speaker 3: They found that moving distance was not correlated with the
Speaker 3: time since capture. So for a lot of species, you
Speaker 3: might expect that the longer you go in between captures,
Speaker 3: the farther away from their original location they might have moved.
Speaker 3: In these salamanders, not the case. The longer you go
Speaker 3: in between captures, it does not, on average effect how
Speaker 3: far away they are from the first time. So the
Speaker 3: question is why do they move so little? There could
Speaker 3: be a number of answers here, and the authors say
Speaker 3: to be fair extreme site fidelity, the extreme site fidelity
Speaker 3: of these salamanders is not necessarily extreme among amphibians. There
Speaker 3: are also some surface amphibians that may have very limited
Speaker 3: movement ranges. The authors could not find any reason based
Speaker 3: on the environment itself that would limit movement. In other words,
Speaker 3: there were no gaps in the movement patterns that would
Speaker 3: indicate environmental features they were trying to avoid, And so
Speaker 3: they say their best guess is that this hyper sedentary
Speaker 3: lifestyle 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 cinch, 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 an evasive maneuver, essentially like it's trying to
Speaker 3: get away from you. They can move quickly. It just
Speaker 3: seems like undisturbed in their natural environment. If you use
Speaker 3: the capture recapture method, they haven't moved much after a year,
Speaker 3: after two years and so on.
Speaker 2: 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 2: H Yeah. I mean, obviously we're dealing with creatures that are,
Speaker 2: like we said, difficult to observe anyway, and you know,
Speaker 2: we can't count out various other organisms that then scavenge
Speaker 2: a dead one. We also have to take into account,
Speaker 2: you know, the movements of the waters that have at
Speaker 2: least historically been attributed to ones occasionally washing out and
Speaker 2: so forth. And even if one didn't wash out all
Speaker 2: the way to where humans could have observed them, it
Speaker 2: might wash them out to where other organisms would have
Speaker 2: a shot at scavenging them. But still it's an interesting tidbit.
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 2: Yeah, And like I said, that could be because it
Speaker 2: is they do get periodically fleshed out, I'm guessing, or yeah,
Speaker 2: 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. Though. Vulnerability to
Speaker 3: water pollution I think is also true of many surface amphibians,
Speaker 3: who are especially vulnerable because of the permeability of their skin.
Speaker 3: So yeah, another reason why, I mean, not like we
Speaker 3: needed that. Many more reasons why water pollution is a
Speaker 3: bad thing. But here's another one. But final note, if
Speaker 3: you haven't seen a picture of the ulm, you should
Speaker 3: look this one up. You want to see this flesh.
Speaker 2: Oh yeah, absolutely, it's a very it's.
Speaker 3: A very Cronenberg biodesign.
Speaker 2: Yeah, they're like I say, they're a little creepy, a
Speaker 2: little cute. They're very unique. All right. I want to
Speaker 2: get into a topic here that that came up early
Speaker 2: on in my research and a paper that came up
Speaker 2: pretty early on in researching these episodes, and it has
Speaker 2: to do with intra gilled predation, that's the killing and
Speaker 2: eating of potential competitors with any ecosystem, which is apparently
Speaker 2: a pretty big deal in the food chain of the
Speaker 2: Hypogean world. So, as we discussed in previous episodes and
Speaker 2: specifically in the last episode, you know, bat guano is
Speaker 2: kind of an alternative sunlight that forms sort of the
Speaker 2: base of the subterrane and ecosystem a lot of the
Speaker 2: times as bats roost in the cave and defecate, thus
Speaker 2: bringing new resources for various organisms to feed on, which
Speaker 2: in turn feed other consumers. And as discussed in a
Speaker 2: twenty twenty one paper published in Scientific Reports by param
Speaker 2: Mutchova at all quote the food web in a subterranean
Speaker 2: ecosystem is driven by introgild predation. So in this paper
Speaker 2: they drive home some of what we discussed last time
Speaker 2: that quote, detrit us based food webs are prevalent in
Speaker 2: cave systems. Though you do have cases where again sunlight
Speaker 2: enters cavern openings or through other fissures, and also have
Speaker 2: situations where some manner of chemo autotrophy is taking place,
Speaker 2: but still, you know, it often falls to back guano
Speaker 2: as well as other transportation networks for dead plants, and
Speaker 2: to try it as such as the gravitation pawn or streams.
Speaker 2: It's like a like a steep sinkhole situation percolating water.
Speaker 2: And also animal cadavers, the animal cadaver being something that is,
Speaker 2: you know, the animal has gone in there and died
Speaker 2: or something has brought the animal 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 it's 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, back guano, 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 2: Be eaten, Yeah, falling in and potentially flowing in in
Speaker 2: the same way that a dead own might flow out
Speaker 2: of a cave, if we're to take that earlier account
Speaker 2: at face value. So anyway, that's the base, and you
Speaker 2: have all of these consumer interactions atop of all that.
Speaker 2: In a cave, and this particular study examined the subterranean
Speaker 2: ecosystem of the Autovaska Cave in Slovakia. The predators they
Speaker 2: examined were all arthropods living in the cave, including a
Speaker 2: species of might a beetle, two different spiders, and a
Speaker 2: couple of other species, and they were able to examine
Speaker 2: DNA in the guts of each species to see what
Speaker 2: they were eating. As expected, they found a complex system
Speaker 2: of intragil predation again killing and eating of potential competitors.
Speaker 2: And they included a handy visual guide that I really liked,
Speaker 2: so I included it here for you to look at, Joe.
Speaker 2: They have essentially five dots scored here on the illustration,
Speaker 2: each one representing one of these five species they looked at.
Speaker 2: In each one is color coded with color coded lines
Speaker 2: indicating which one feeds on which, and you end up
Speaker 2: with this complex almost pretty much a star pattern, but
Speaker 2: with a few more lines on some connections, and sometimes
Speaker 2: there's not a line connecting one 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 2: Right, right, And then you know they acknowledge their limitations
Speaker 2: and their study and so forth, so it's not this
Speaker 2: is not necessarily all that ever happens between these these species,
Speaker 2: but this is what they're they're got syndicated when they
Speaker 2: were studied, and so they stress that intragil predation is
Speaker 2: often important in nitrogen poor diets, as is cannibalism, which
Speaker 2: that which they found evidence of, and it should be
Speaker 2: stressed that scavenging may be part of both cases. So
Speaker 2: you know, on one hand, you have like straight up
Speaker 2: predation like well there's my competitor, I've got the drop
Speaker 2: on them. I shall eat them, but also a situation
Speaker 2: 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 2: Yeah, because you know, otherwise going toe to toe with
Speaker 2: someone or something in the ecosystem that is your equal, Like,
Speaker 2: that's that's a gamble, and survival is on the line
Speaker 2: regardless if you engage in that struggle, And you might
Speaker 2: only engage in that struggle if survival is already on
Speaker 2: the line. And yeah, in the impoverished food web of
Speaker 2: the dark, you get what you get. You don't pitch
Speaker 2: a fit. Each of the species here that they looked
Speaker 2: at consumed a wide variety of prey and indulged in
Speaker 2: integral predation as presumably necessary. So it would seem, based
Speaker 2: on what I was reading here that Yeah, while you know,
Speaker 2: integral predation of course, as you said, occurs in the
Speaker 2: sunlit world as well, and in the oceans and so forth,
Speaker 2: within the cave environment, it might be more pronounced again
Speaker 2: due to the limited scope of the available biomass, available
Speaker 2: 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 2: Yeah. So yeah, I thought this was very interesting. But
Speaker 2: I want to get into this other area here for
Speaker 2: the remainder of the episode here having to do with
Speaker 2: outsiders in the cave, creatures who have come into the
Speaker 2: cave to take advantage of what is there. Because once again,
Speaker 2: and there's the there, the there's the idea that the
Speaker 2: cave environment comes with pros and cons. One con as
Speaker 2: we as we've discussed already, is that the food chain
Speaker 2: here is just less robust, uh specialized, obligate. Cave organisms
Speaker 2: generally have carved out a very narrow niche in which
Speaker 2: to live. A big pro, however, is, as with the OLM,
Speaker 2: you're often dealing with fewer predators and a more secluded life.
Speaker 3: Mm hmm.
Speaker 2: It's like the Phantom of the Opera. You know, you
Speaker 2: have this vast catacomb empire over which to rule and
Speaker 2: row your boat around, and you have great acoustics, you know,
Speaker 2: for your singing, for your your your cool pipe organ.
Speaker 2: But the real music scene is upstairs in the sunlit world,
Speaker 2: and you are, you know, to a large extent cut
Speaker 2: off from that.
Speaker 3: You really need to kidnap a singer from up there
Speaker 3: to to make your make your songs work better down there. Yeah.
Speaker 2: Yeah, So there there is a potential advantage here for
Speaker 2: creatures of both worlds and creatures of the surface that
Speaker 2: have figured out how and when to venture into caves
Speaker 2: to take advantage of the creatures that live there, at
Speaker 2: least live there periodically. And you know, I don't think
Speaker 2: we've run across anything that's going in to harvest the olms.
Speaker 2: But as we've been discussing one of the most abundant
Speaker 2: life forms you might pray or scavenge upon the in
Speaker 2: caverns are creatures that spend part of their time there
Speaker 2: as well. That being bats, they roost in great numbers.
Speaker 2: They enjoy a great deal of security there. But a
Speaker 2: 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 2: Well, a number of organisms. Actually, I was looking at
Speaker 2: a paper from nineteen seventy two. This is by Winkler
Speaker 2: and Atoms titled utilization of Southwestern Bat Caves by Terrestrial Carnivores,
Speaker 2: and this is published in the Journal of the American
Speaker 2: Middland Naturalist. And they put out that various predators venture
Speaker 2: into caves to enjoy the occasional bat feast, either via
Speaker 2: active hunting or by scavenging for fallen bats. And this
Speaker 2: includes broadly like various reptiles, raptorial birds, and mammals. For instance,
Speaker 2: they point out that at Bracken Cave, raccoons and some
Speaker 2: skunks were observed to venture into the cave to prey
Speaker 2: on fallen bats at the cave mouth. Because you know,
Speaker 2: I think we discussed this at least in passing earlier.
Speaker 2: You have large populations of bats residing in many of
Speaker 2: these caves, and occasionally bats do fall be they you know,
Speaker 2: young bats, older bats, in firm bats, et cetera. They're
Speaker 2: just too many of them this for this not to happen.
Speaker 2: It will occasionally rain a little bit of food in
Speaker 2: the form of a bat, and an organism that is
Speaker 2: operated into tunistic enough can get in there and collect
Speaker 2: those and eat them, or you know, eat them before
Speaker 2: they're able to crawl across the cave floor and then
Speaker 2: 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 2: That's right. So ringtail cats were observed at another cave,
Speaker 2: but it seemed as if, especially at Bracken Cave, raccoons
Speaker 2: were the most likely to take advantage of the bat
Speaker 2: bounty during both the day and the night. And in
Speaker 2: you know, this this makes sense concerning the raccoon, because,
Speaker 2: as we've talked about in the show before, you know,
Speaker 2: they're they're great opportunists. Uh, they are. They're nocturnal omnivores,
Speaker 2: and 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 going.
Speaker 2: Yeah, I remember talking about like, for instance, they are
Speaker 2: they are they're great opportunistic organisms that can adapt to
Speaker 2: various environments. So they've done quite well with urban environments.
Speaker 2: Uh and uh and yeah. We also discussed the heartbreaking
Speaker 2: video footage that you can look up online of a
Speaker 2: raccoon attempting to to dunk it's uh it's a plunder
Speaker 2: of cotton candy into the water, and then seemingly confused
Speaker 2: as it draws the bounty back out of the water
Speaker 2: and finds that it is no longer uh there for it.
Speaker 2: It's again kind of heartbreaking to.
Speaker 3: Watch 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 behaviors observed in animals, including
Speaker 3: the apparent washing of food. But again, I think there
Speaker 3: was a question of whether that's really what raccoons are
Speaker 3: doing or not.
Speaker 2: Yeah, but they're they're they're they're little paws, they are
Speaker 2: little hands. If you will are are are excellent. I've
Speaker 2: seen it described that they can essentially see with their
Speaker 2: hands in ways that we could maybe relate to on
Speaker 2: some level, But as is often the case with the
Speaker 2: sense worlds of animals, of non human animals, we generally
Speaker 2: can't fully imagine what it's like. Like they can see
Speaker 2: with their hands is the best way that we can
Speaker 2: 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 2: Yeah. Now this cave in question, Bracken Cave. This is
Speaker 2: a Texas cave outside of San Antonio that is home
Speaker 2: to the largest known bat colony in the world. Some
Speaker 2: twenty million Mexican free tail bats roost here between March
Speaker 2: and October. This also apparently makes it the largest known
Speaker 2: concentration of mammals period, including humans. I'm assuming, and I
Speaker 2: imagine this takes into account the size of the cave
Speaker 2: and the estimation estimated concentration of bats as compared to
Speaker 2: human cities. But even among human cities, there are only
Speaker 2: something like six cities with populations of more than twenty million.
Speaker 2: So we're talking a lot of bats. And I didn't run,
Speaker 2: I didn't look up or do the math on this,
Speaker 2: but you know, you think about twenty million bats, how
Speaker 2: many bats are going to potentially fall? So that does
Speaker 2: create a certain opportunity for animals that are willing to
Speaker 2: get in there day or night and pick them off
Speaker 2: before 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 2: Yeah. Now, reptiles also get on in the action as well,
Speaker 2: as that paper indicated, And one of the more alarming examples,
Speaker 2: I don't know, it could be alarming, depends on what
Speaker 2: you think about snakes is the example of yellow red
Speaker 2: rat snakes found in a cave in Mexico that is
Speaker 2: sometimes referred to as the Cave of Hanging Snakes.
Speaker 3: Hanging snakes.
Speaker 2: Yes, so, the yellow red rat snake is endemic to
Speaker 2: Mexico and Central America, so it's fairly widespread. It's non venomous.
Speaker 2: It prays mostly on rodents and birds and lizards, but
Speaker 2: also on the menu are bats. So the Mexican cave
Speaker 2: in question is Cantemo Cave in the Mexican state of
Speaker 2: kintani Roo, about one hundred and eighty miles from Cancun,
Speaker 2: known locally just as the bat Cave. According to Jose
Speaker 2: Maria Morells, writing for Atlas Obscura, the snakes here have
Speaker 2: developed an amazing method of eating those bats that doesn't
Speaker 2: involve picking them off on the cave floor. So what
Speaker 2: they do, apparently, is they crawl up into the cracks
Speaker 2: in the ceiling of the cave as well as high
Speaker 2: up on the cave walls. And then when the bats,
Speaker 2: you know, the bats are roosting in there, so they
Speaker 2: leave and then they come back. They leave to feed,
Speaker 2: and then they come back. And when they're doing this,
Speaker 2: when they're going in or out of the cave, that
Speaker 2: is when the snakes will either dangle down or otherwise
Speaker 2: like lash out to catch a passing bat in its mouth.
Speaker 3: Wow.
Speaker 2: And I've included a couple of photos here for you
Speaker 2: to look at, Joe, one of the snake grabbing having
Speaker 2: grabbed a bat and it's like, you know, just swallowing it.
Speaker 2: And then there's another one of the snake up in
Speaker 2: the recesses. This is these are actually, these are excellent photos.
Speaker 2: They're from a Newsweek article that put that that profiled
Speaker 2: 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 2: Now you mentioned looking up images of this, Yeah, there
Speaker 2: there are a lot of images of these of these snakes.
Speaker 2: There's some footage as well. This cave has become an
Speaker 2: ecotourism destination, so a lot of people have gotten to
Speaker 2: go there. It's been covered in a lot of by
Speaker 2: a lot of news outlets, various documentaries, so you can
Speaker 2: definitely see some images of these snakes either you know,
Speaker 2: dangling from the ceiling or consuming the bats that they
Speaker 2: 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 like how
Speaker 3: long have these snakes specialized in attacking bats this way?
Speaker 3: And like what were they doing before that?
Speaker 2: Yeah? Yeah, I mean I guess it's kind of a
Speaker 2: natural extrapolation of surface world environments, especially thinking our boreal environments, right. Yeah,
Speaker 2: the cave is just like a novel form of that.
Speaker 2: And with the bat population, you have just such a
Speaker 2: concentration of potential prey. You're going to have organisms that
Speaker 2: are drawn to it and ones that are able to
Speaker 2: adapt their existing practices, their existing predation and scavenging practices
Speaker 2: to it, or as with the raccoon, are just generally
Speaker 2: great opportunists. You know they're going to be able to
Speaker 2: 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 2: I think, so. I think a fourth episode will wrap
Speaker 2: it up for this journey into the caves, but you know,
Speaker 2: after that, we'll probably be back in the future at
Speaker 2: some point or another. Caves and their ecosystems and human
Speaker 2: traditions associated with them are just too fascinating, all right.
Speaker 2: In the meantime, we're going to go ahead and remind
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