WEBVTT - Life in the Hypogean World, Part 3 0:00:03.040 --> 0:00:06.800 Welcome to Stuff to Blow Your Mind production of iHeartRadio. 0:00:12.760 --> 0:00:14.600 Hey you welcome to Stuff to Blow Your Mind. My 0:00:14.680 --> 0:00:15.960 name is Robert Lamb. 0:00:15.720 --> 0:00:18.120 And I am Joe McCormick, and we're back with part 0:00:18.239 --> 0:00:23.400 three of our series on cave biology and cave environments. 0:00:24.239 --> 0:00:25.799 Let's see what did we talk about in the last 0:00:25.800 --> 0:00:28.040 two episodes of the series. Obviously, if you haven't listened 0:00:28.040 --> 0:00:30.320 to those already, maybe you should go back and check 0:00:30.360 --> 0:00:33.199 those out first, But if you'd rather just jump in here, 0:00:33.320 --> 0:00:36.600 that's okay too. In the previous parts, we talked about 0:00:36.840 --> 0:00:40.919 some of the common characteristics of cave environments and especially 0:00:40.920 --> 0:00:45.519 in ways that would affect animal life. We talked about 0:00:45.920 --> 0:00:49.400 the presence of guano in some caves, bat dropping guano 0:00:49.520 --> 0:00:52.040 as sort of the base of a food chain, the 0:00:52.240 --> 0:00:55.480 equivalent of sunlight to the outside world to the inside 0:00:55.480 --> 0:00:58.760 of the cave. And we also talked about some specific 0:00:58.920 --> 0:01:03.480 cave organism, such as the blind Mexican cavefish, about which 0:01:03.520 --> 0:01:06.200 there has been a lot of research research on how 0:01:06.280 --> 0:01:10.480 exactly these fish evolve. These various populations of fish in 0:01:10.560 --> 0:01:15.040 northeastern Mexican caves evolved to lose their sight and lose 0:01:15.080 --> 0:01:18.240 the pigment in their flesh and so forth. Why that 0:01:18.280 --> 0:01:21.960 evolutionary pathway takes place in the cave environment and so forth. 0:01:22.280 --> 0:01:27.200 Yeah, so we're so we've established to a degree, the 0:01:27.920 --> 0:01:31.600 cave environment, the cave ecosystem. We've talked about characteristics, We've 0:01:31.600 --> 0:01:34.600 talked about some individual species, and we're going to kind 0:01:34.600 --> 0:01:36.399 of continue that trend here. We're going to talk about 0:01:36.480 --> 0:01:41.800 some more specific organisms that make their homes in the 0:01:41.840 --> 0:01:46.320 cave environment, or we're going to look at creatures that 0:01:46.440 --> 0:01:51.120 dip into that ecosystem, dip into that biomass that is 0:01:51.160 --> 0:01:52.440 already living in the cave. 0:01:52.960 --> 0:01:54.600 All right, well, I think I'm going to kick things 0:01:54.640 --> 0:01:56.880 off today with a full cave entry. 0:01:57.800 --> 0:01:58.800 All right, let's do it. 0:01:59.040 --> 0:02:00.760 No, no halfway on this one. 0:02:01.440 --> 0:02:02.760 An obligate cave dweller. 0:02:03.120 --> 0:02:06.480 Right, So, according to one source I was reading, actually 0:02:06.600 --> 0:02:09.960 this has been claimed as the first animal to be 0:02:10.080 --> 0:02:14.520 recognized as permanently adapted to a cave environment. I couldn't 0:02:14.600 --> 0:02:17.080 verify that priority, but that's the claim at least, so 0:02:17.080 --> 0:02:21.560 that may be true. This animal is an aquatic cave 0:02:21.840 --> 0:02:27.680 salamander called the oulm, also known as the proteus scientific 0:02:27.760 --> 0:02:32.040 name Proteus. I think you would say Anguinus proteus a 0:02:32.240 --> 0:02:39.000 n g ui in us. The oulm occupies underground waterways 0:02:39.200 --> 0:02:44.160 in Europe, especially Kars caves of the Dynaric Mountains, which 0:02:44.320 --> 0:02:48.000 is the region of the Balkans along the eastern coast 0:02:48.040 --> 0:02:51.120 of the Adriatic Sea, so you can think east of Italy, 0:02:51.160 --> 0:02:54.960 across the Adriatic from Italy. And I was looking around 0:02:55.000 --> 0:02:57.560 for some good sources on the history of human knowledge 0:02:57.560 --> 0:02:59.840 of this animal, because I know the first writings about 0:02:59.840 --> 0:03:03.280 it were very interesting. And I came across a paper 0:03:03.440 --> 0:03:06.480 in the Journal of Cave and Karst Studies from twenty 0:03:06.520 --> 0:03:11.519 twenty one by Evo Lucik called an underworld tailored to tourists, 0:03:11.600 --> 0:03:16.480 a dragon, a photomodel, and a bioindicator. And Lucik does 0:03:16.520 --> 0:03:19.280 an interesting thing in this article. It's not really focused 0:03:19.280 --> 0:03:22.240 on biology. Instead, he's sort of focused on the history 0:03:22.280 --> 0:03:26.680 of how this animal has been perceived and categorized by 0:03:26.720 --> 0:03:30.040 the media and the public. So the earliest writings about 0:03:30.040 --> 0:03:32.680 the ulm are sort of famous. There is an account 0:03:32.760 --> 0:03:36.000 in the writing of a seventeenth century author and natural 0:03:36.080 --> 0:03:45.200 historian named Johann Weikard von valvasor VLVASR. Valvasor, who was 0:03:45.320 --> 0:03:50.000 from the region then known as Carneola what is today Slovenia, 0:03:50.680 --> 0:03:54.880 and Valvasor famously published a sort of encyclopedia of the 0:03:54.960 --> 0:03:58.600 region known as The Glory of the Duchy of Carniola, 0:03:59.000 --> 0:04:01.720 and because of the sting geology of this region with 0:04:01.760 --> 0:04:05.280 the kars the caves, the work did contain some investigations 0:04:05.280 --> 0:04:09.120 of the local its caves, its associated culture and life. 0:04:09.800 --> 0:04:16.000 So Here, summarizing Valvasor, Lucik says that around sixteen eighty nine, 0:04:16.360 --> 0:04:20.640 Valvasour reported that he had heard stories from peasants in 0:04:20.680 --> 0:04:25.240 a region known as the Vernica that they had seen 0:04:25.400 --> 0:04:29.479 a baby dragon in the local water source known as 0:04:29.520 --> 0:04:33.120 the Bayliss Spring, and the people who knew this spring 0:04:33.240 --> 0:04:35.960 said that the water would flow from it reliably twice 0:04:35.960 --> 0:04:39.760 a day, once around midnight and once again around nine am, 0:04:39.960 --> 0:04:43.039 and this apparently was linked to some kind of belief 0:04:43.240 --> 0:04:48.159 in an underground dragon, which, when it became angry, would 0:04:48.200 --> 0:04:51.039 spit out water and perhaps one of its own young 0:04:51.800 --> 0:04:54.279 One of the peasants that Valvasore spoke to said he 0:04:54.320 --> 0:04:57.480 had seen three young dragons spit up in this way 0:04:57.480 --> 0:05:00.960 by the spring, and a local male care claimed that 0:05:01.080 --> 0:05:03.600 at one point he took one of the baby dragons 0:05:03.640 --> 0:05:05.880 home with him and it was about as big as 0:05:05.880 --> 0:05:07.719 his hand and looked like a lizard. 0:05:08.920 --> 0:05:11.159 And it does sort of look like a lizard, but 0:05:11.240 --> 0:05:14.080 I would say a little bit lizard, a little bit 0:05:14.240 --> 0:05:18.960 vampire princess, a little bit just you know, it depends 0:05:18.960 --> 0:05:22.240 what the lightings like. But yeah, it's this long, slender 0:05:22.680 --> 0:05:27.919 organism with this elongated head and these wonderfully dainty little limbs. 0:05:28.680 --> 0:05:32.000 Yeah, so it is a salamanderin form. It has a 0:05:32.040 --> 0:05:35.680 kind of flat, almost elongated I was gonna say shovel 0:05:35.720 --> 0:05:37.840 shaped head, but it's not really shovel shaped. It's more 0:05:38.520 --> 0:05:40.560 kind of if you look down from above, the head 0:05:40.600 --> 0:05:43.760 is sort of crocodile head shaped. But yeah, it is 0:05:43.800 --> 0:05:47.960 a kind of flat head. It has frilly red gills 0:05:48.040 --> 0:05:51.200 extending out from the base of its head around its neck. 0:05:51.520 --> 0:05:54.080 It has yeah, as you say, delicate little limbs that 0:05:54.160 --> 0:05:56.160 don't look like you know, they would do a whole lot, 0:05:56.240 --> 0:05:58.800 but it can use them. And otherwise the body is 0:05:58.920 --> 0:06:04.800 like a long kind of white snake. It is a translucent, white, 0:06:05.800 --> 0:06:09.440 fleshy skin going in the snakelike shape. I've heard some 0:06:09.600 --> 0:06:11.880 authors say that if you look at it closely, you 0:06:11.920 --> 0:06:15.359 can actually sort of see its organs through its skin 0:06:15.680 --> 0:06:18.080 that like the light can sort of penetrate it, and 0:06:18.120 --> 0:06:21.120 you can see its insides. And you can look up 0:06:21.160 --> 0:06:24.120 pictures of the ulm online. They're they're pretty readily accessible. 0:06:24.600 --> 0:06:27.720 It's it's a creepy looking organism. I mean, it does 0:06:28.560 --> 0:06:30.640 in some of these photos it almost seems to kind 0:06:30.640 --> 0:06:33.760 of glow because I guess of the maybe low light 0:06:33.839 --> 0:06:37.480 conditions in which it is being photographed, and its very 0:06:37.520 --> 0:06:39.760 pale skin is like reflecting a lot of light. 0:06:40.120 --> 0:06:42.440 Yeah, I mean, I guess, kind of creepy, but also 0:06:43.040 --> 0:06:47.159 just haunting, almost kind of elfin in its in its appearance, 0:06:47.200 --> 0:06:49.360 you know, like this is a being from another world 0:06:49.880 --> 0:06:53.640 and it's its body and form, it's is entirely alien 0:06:53.680 --> 0:06:54.200 to us. 0:06:54.600 --> 0:06:56.560 And it's funny. So the rest of this paper by 0:06:56.640 --> 0:07:02.320 Lucik really emphasizes the to which sort of mythological themes 0:07:02.360 --> 0:07:06.480 have permeated the public understanding of this creature and are 0:07:06.560 --> 0:07:11.000 even in some ways still prevalent because of the ways 0:07:11.080 --> 0:07:16.120 that this creature is marketed by the local cave systems 0:07:16.160 --> 0:07:20.160 as a tourist attraction, and those that marketing places a 0:07:20.160 --> 0:07:23.040 lot of emphasis on mythological themes, like referring to it 0:07:23.080 --> 0:07:27.360 as a dragon. However, of course, over the following generations 0:07:27.400 --> 0:07:31.760 after valvasor, a scientific view of this creature began to 0:07:31.800 --> 0:07:34.679 take shape. That it was not a dragon, of course, 0:07:34.720 --> 0:07:39.440 but an amphibian, an amphibian that lived in waterways underneath 0:07:39.440 --> 0:07:43.680 the earth, which could explain why specimens were sometimes disgorged 0:07:43.720 --> 0:07:48.040 from a spring or cave opening after heavy rains. And 0:07:48.120 --> 0:07:51.040 so I wanted to get a scientific perspective on this creature, 0:07:51.400 --> 0:07:53.840 and I dug up a paper that I thought was interesting. 0:07:53.880 --> 0:07:56.360 This was a paper published in the Journal of Zoology 0:07:56.400 --> 0:08:00.720 in twenty twenty by belaws, l, Warn and Hurts called 0:08:00.840 --> 0:08:05.800 extreme site fidelity of the oulm Proteus anguinus revealed by 0:08:05.960 --> 0:08:10.280 a long term capture mark recapture study. So I'm going 0:08:10.320 --> 0:08:12.320 to try to do a bit of a recap of 0:08:12.360 --> 0:08:14.840 what this paper does in reviewing some of the main 0:08:14.880 --> 0:08:19.240 biological characteristics of this animal and then discuss the findings 0:08:19.240 --> 0:08:22.080 of their specific experiment. One thing they do, and this 0:08:22.160 --> 0:08:24.520 is important to do, I think in the episodes of 0:08:24.560 --> 0:08:27.600 this series is they remind us about the common characteristics 0:08:27.920 --> 0:08:31.600 of cave habitats. There can be some variation between different caves, 0:08:31.640 --> 0:08:36.079 but cave ecosystems are usually going to be shaped by 0:08:36.600 --> 0:08:40.040 a reduction or total absence of light that changes a 0:08:40.080 --> 0:08:44.240 lot about how organisms survive food scarcity. This is common 0:08:44.240 --> 0:08:47.640 to a lot of caves because, as you might recall 0:08:48.160 --> 0:08:51.360 other organisms we talked about, like the blind Mexican cavefish, 0:08:51.400 --> 0:08:54.720 seem to have adapted to their environment by having lower 0:08:54.840 --> 0:08:59.880 nutritional or energy needs than their surface surface variant cousins. 0:09:00.520 --> 0:09:03.640 That they need less food to survive, and they have 0:09:03.679 --> 0:09:05.959 to adapt to be this way because there's less food 0:09:06.000 --> 0:09:08.800 in a cave. Another thing the authors identify is what 0:09:08.840 --> 0:09:12.720 they call simplified communities. I looked this up to make 0:09:12.760 --> 0:09:14.920 sure I was understanding it right, so I found one 0:09:14.960 --> 0:09:18.360 other paper discussing this concept in the journal Bioscience, and 0:09:18.679 --> 0:09:22.560 according to their definition, simplification seems to be a quote 0:09:22.600 --> 0:09:26.520 reduction in niche diversity. So I think that means you know, 0:09:26.640 --> 0:09:30.199 fewer ways for organisms to specialize, which kind of makes 0:09:30.200 --> 0:09:34.600 sense within a cave. And then finally they mention that 0:09:34.600 --> 0:09:37.080 the cave environments are usually shaped by the fact that 0:09:37.120 --> 0:09:40.880 there the cave environment is a major buffer against changes 0:09:41.000 --> 0:09:45.480 in climate and other environmental variations. So living in a 0:09:45.559 --> 0:09:50.240 deep cave largely removes the variation of things like the 0:09:50.320 --> 0:09:54.240 night day cycle, seasonal changes to weather, and so forth. 0:09:54.320 --> 0:09:58.400 So a cave environment, though some changes can still come. 0:09:58.480 --> 0:10:00.960 And obviously if you're living in an under ground waterway, 0:10:01.840 --> 0:10:05.360 like changes in water flow are possible, like heavy rains 0:10:05.400 --> 0:10:08.880 could still cause you know, increasing currents in the in 0:10:08.920 --> 0:10:11.520 the waterway and so forth. But there are going to 0:10:11.559 --> 0:10:16.680 be fewer cyclical, seasonal day, night, and other environmental changes 0:10:16.720 --> 0:10:19.000 in a cave than there are outside. 0:10:19.120 --> 0:10:20.720 You mean, of course, you also might want to throw 0:10:20.720 --> 0:10:25.319 in seasonal habitation by certain organisms such as bats or 0:10:25.920 --> 0:10:30.680 historically things like a cave bear. But even then, the 0:10:30.720 --> 0:10:34.199 deeper into the cave you get, you could potentially be 0:10:34.240 --> 0:10:37.360 even further removed from the influence of sad. 0:10:37.240 --> 0:10:40.920 Organisms, right, And so the authors say, as several authors 0:10:40.920 --> 0:10:43.520 we've looked at have mentioned this, that the evolutionary ecology 0:10:43.559 --> 0:10:46.560 of caves is kind of hard to study for maybe 0:10:46.600 --> 0:10:51.000 obvious reasons, like aquatic caves especially are kind of hard 0:10:51.000 --> 0:10:55.680 to access, they require difficult diving and so forth. And 0:10:56.040 --> 0:10:58.600 they say that in the continent of Europe, vertebrates that 0:10:58.679 --> 0:11:02.840 are fully adapted to cave life are actually somewhat rare. 0:11:02.880 --> 0:11:04.800 There are more species that might go in and out 0:11:04.800 --> 0:11:08.280 of caves, but the ones that are the full on troglobions, 0:11:08.400 --> 0:11:12.400 the fully adapted to cave organisms that there are not 0:11:12.440 --> 0:11:14.720 a whole lot of those. But one of the best 0:11:14.720 --> 0:11:18.480 known exceptions is the ome. It is not only a 0:11:18.720 --> 0:11:23.400 fully cave adapted organism, it is the largest cave dwelling 0:11:23.559 --> 0:11:27.360 vertebrate on Earth. The authors cite a couple of studies 0:11:27.679 --> 0:11:32.319 from boulog in nineteen ninety four and Tronte in two 0:11:32.360 --> 0:11:35.840 thousand and seven to suggest that the ancestors of the 0:11:35.880 --> 0:11:39.720 OLM probably colonized caves somewhere between eight point eight and 0:11:39.880 --> 0:11:45.120 twenty million years ago. All known populations except for one, 0:11:45.480 --> 0:11:49.480 have regressed eyes and lack pigment in their bodies, so 0:11:49.520 --> 0:11:53.960 they appear eyeless and pale or translucent. The one accepted 0:11:54.000 --> 0:11:58.320 population is in a cave system in southeast Slovenia. 0:11:58.400 --> 0:12:01.560 There's one called the black Ole. I remember running across, 0:12:01.600 --> 0:12:04.400 and it stuck with me because that sounds like such 0:12:04.400 --> 0:12:08.680 a like a death metal home in your European caverns. 0:12:09.200 --> 0:12:11.840 But apparently just the difference is for some reason, this 0:12:11.920 --> 0:12:15.800 is the one population that has retained its pigment within 0:12:15.880 --> 0:12:19.959 the caves. They are top predators, which is kind of 0:12:20.000 --> 0:12:21.680 funny because when you look at them, they don't look 0:12:21.760 --> 0:12:25.560 like top predators. They look kind of unassuming, maybe creepy, 0:12:25.600 --> 0:12:28.439 but you know, they don't look scary. If that distinction 0:12:28.600 --> 0:12:29.040 makes sense. 0:12:29.960 --> 0:12:33.480 Yeah, I guess it comes down to again, how scary 0:12:33.559 --> 0:12:35.440 do you have to be in order to be the 0:12:35.480 --> 0:12:39.040 top predator in a cave ecosystem where again, you have 0:12:39.360 --> 0:12:42.240 you do have food chain, you do have a certain 0:12:42.240 --> 0:12:45.840 amount of biomass available, but it is it is, it's 0:12:45.880 --> 0:12:48.400 all nache. It's reduced, so you're not going to have 0:12:50.080 --> 0:12:52.920 these enormous organisms. You know, everything's going to be on 0:12:52.960 --> 0:12:56.160 a smaller, hungrier, and more versatile scale. 0:12:56.520 --> 0:12:59.240 Yeah, totally. And to be clear, I mean I'm not 0:12:59.280 --> 0:13:02.600 saying I actually think scariness is a biological indicator of 0:13:02.880 --> 0:13:04.880 whether you're a top predator or not. But you know, 0:13:04.920 --> 0:13:08.520 it's just the intuitions they don't seem to match. But 0:13:08.600 --> 0:13:10.800 they are the top predator in their cave environments. They 0:13:10.800 --> 0:13:15.440 prey on small animals like cave shrimp, snails, little insects, 0:13:15.880 --> 0:13:18.560 and they have no natural predators of their own, so 0:13:18.600 --> 0:13:21.679 there's nothing they have to normally watch out for preying 0:13:21.679 --> 0:13:25.200 on them. They're the top of the pyramid because they 0:13:25.240 --> 0:13:27.320 have no predators. There's a part later in this paper 0:13:27.360 --> 0:13:31.240 where the authors observe that the olm do not seem 0:13:31.280 --> 0:13:34.480 to engage in hiding behaviors that they observed. At least 0:13:34.480 --> 0:13:38.560 they said, it's possible that some olms are like hide 0:13:38.600 --> 0:13:41.040 back in cracks and crevices that they were never able 0:13:41.080 --> 0:13:43.560 to access on their dives, so you know, they couldn't 0:13:43.679 --> 0:13:46.920 locate them back there. But the ones they saw float 0:13:47.000 --> 0:13:49.640 out in the open, maintaining their place within the current 0:13:49.720 --> 0:13:52.480 of the cave waterway, Like you know, they're just not 0:13:52.520 --> 0:13:55.600 worried about that. They don't have to go hide. Now, 0:13:55.640 --> 0:13:58.560 another way in which our naive intuitions about what it 0:13:58.600 --> 0:14:01.120 means to be a top predator and be violated. You 0:14:01.200 --> 0:14:04.640 might hear top predator and you think voracious appetite. You know, 0:14:04.640 --> 0:14:08.520 they're eating a lot, eating everything around them. No, Actually, 0:14:08.559 --> 0:14:14.240 the ole is famous for having an incredibly incredibly elastic 0:14:14.360 --> 0:14:19.280 energy needs, Like it can survive years apparently without food 0:14:19.400 --> 0:14:22.480 and can avoid starvation, so it can go into very 0:14:22.560 --> 0:14:26.280 low energy mode, can maintain a low metabolism and can 0:14:26.320 --> 0:14:28.480 go for a long time without food. 0:14:29.640 --> 0:14:34.040 Yeah, yeah, because again the reduced availability of prey and 0:14:34.040 --> 0:14:35.920 a given environment, you need to be able to really 0:14:35.920 --> 0:14:38.760 stretch out those the spaces between meal times. 0:14:39.040 --> 0:14:43.200 It's noted that they are neotonic, meaning they retain juvenile 0:14:43.240 --> 0:14:46.200 features into adulthood, and there's some other salamander species that 0:14:46.560 --> 0:14:50.040 do this as well. They can tolerate water with very 0:14:50.200 --> 0:14:54.360 little dissolved oxygen in it, so they have low food 0:14:54.480 --> 0:14:58.760 energy needs and low oxygen needs. And while they are 0:14:58.800 --> 0:15:02.320 blind to light, they do have a number of compensating 0:15:02.480 --> 0:15:07.000 sense mechanisms. The authors mention one of them is what's 0:15:07.040 --> 0:15:11.520 known as raeotaxis. Raeotaxis is the ability to sense the 0:15:11.600 --> 0:15:15.360 direction of flow within the water, and then that's also 0:15:15.520 --> 0:15:19.520 paired with a behavioral instinct that causes the salamander to 0:15:19.760 --> 0:15:23.880 turn to orient its body facing into the water flow, 0:15:24.360 --> 0:15:26.520 and this is a common way for fish and other 0:15:26.560 --> 0:15:31.360 aquatic organisms to remain stationary rather than drifting away with 0:15:31.440 --> 0:15:36.080 water currents. They also use other senses than site. They 0:15:36.120 --> 0:15:39.720 have underwater hearing, they use their sense of smell or oldfaction, 0:15:40.360 --> 0:15:43.360 and they appear to have a magnetic sensoryability as well, 0:15:43.400 --> 0:15:47.080 which may help them orient with respect to Earth's magnetic field, 0:15:47.840 --> 0:15:52.480 possibly useful for orientation and navigation. As I said, the 0:15:52.520 --> 0:15:56.080 ulm has very restricted food needs like some other troglobiants 0:15:56.400 --> 0:15:59.360 we've discussed. You remember the blind Mexican cave fish had 0:15:59.480 --> 0:16:02.880 very low food needs compared to its surface variant cousin. 0:16:03.320 --> 0:16:08.200 They have what the authors call extreme life history adaptations, 0:16:08.640 --> 0:16:12.720 meaning their life just appears to sort of sort of 0:16:12.760 --> 0:16:16.480 go in slow motion compared to salamanders you might find 0:16:16.480 --> 0:16:19.040 on the surface. So I was looking up the maximum 0:16:19.080 --> 0:16:22.280 life span of surface amphibians, and of course that varies, 0:16:22.320 --> 0:16:23.960 but you know, on average it's going to be more 0:16:23.960 --> 0:16:26.920 in the range of ten to twenty years. For large 0:16:26.920 --> 0:16:31.160 amphibians that live on the surface. The olem is thought 0:16:31.200 --> 0:16:36.600 to live for one hundred years or more, with females 0:16:36.640 --> 0:16:41.040 only reproducing once every twelve and a half years roughly. 0:16:41.400 --> 0:16:44.960 So that is incredibly long life for an amphibian, incredibly 0:16:45.000 --> 0:16:49.000 long in between mating and reproduction. So this experiment tried 0:16:49.040 --> 0:16:52.560 to study the behavior of the olm, especially the movement 0:16:52.600 --> 0:16:56.280 and migratory patterns of the olm, by using a capture 0:16:56.360 --> 0:16:59.120 mark and recapture method. So you know, they catch one, 0:16:59.200 --> 0:17:02.040 they mark it, and then they would come back and 0:17:02.080 --> 0:17:04.440 see if they could capture the same ones again later, 0:17:04.640 --> 0:17:07.760 note where they were relative to the original capture and 0:17:07.800 --> 0:17:13.080 so forth. Specifically, they were studying an eastern Herzegovinian population 0:17:13.800 --> 0:17:18.320 and the authors found what they called extreme site fidelity. 0:17:18.840 --> 0:17:22.960 Most of the creatures that they captured had barely moved 0:17:23.160 --> 0:17:26.399 since the years before. The average distance was about five 0:17:26.600 --> 0:17:30.919 meters from the original capture location a year before. And 0:17:31.000 --> 0:17:34.520 they also did multiple interval studies, so like capturing them 0:17:34.520 --> 0:17:36.679 at different times and then checking up on them again. 0:17:38.000 --> 0:17:42.040 They found that moving distance was not correlated with the 0:17:42.119 --> 0:17:45.320 time since capture. So for a lot of species, you 0:17:45.400 --> 0:17:48.600 might expect that the longer you go in between captures, 0:17:48.920 --> 0:17:52.560 the farther away from their original location they might have moved. 0:17:52.840 --> 0:17:55.600 In these salamanders, not the case. The longer you go 0:17:55.680 --> 0:17:58.400 in between captures, it does not, on average effect how 0:17:58.400 --> 0:18:00.920 far away they are from the first time. So the 0:18:01.040 --> 0:18:05.560 question is why do they move so little? There could 0:18:05.560 --> 0:18:08.120 be a number of answers here, and the authors say 0:18:08.160 --> 0:18:12.320 to be fair extreme site fidelity, the extreme site fidelity 0:18:12.359 --> 0:18:17.000 of these salamanders is not necessarily extreme among amphibians. There 0:18:17.040 --> 0:18:20.560 are also some surface amphibians that may have very limited 0:18:20.600 --> 0:18:25.000 movement ranges. The authors could not find any reason based 0:18:25.000 --> 0:18:28.320 on the environment itself that would limit movement. In other words, 0:18:28.359 --> 0:18:31.520 there were no gaps in the movement patterns that would 0:18:31.560 --> 0:18:35.560 indicate environmental features they were trying to avoid, And so 0:18:35.720 --> 0:18:39.679 they say their best guess is that this hyper sedentary 0:18:39.720 --> 0:18:45.080 lifestyle is probably related to energy constraints. The author's right quote. 0:18:45.280 --> 0:18:48.200 We can only speculate that animals feeding on a very 0:18:48.240 --> 0:18:54.400 low food supply and as consequence, resistant to starvation, reproducing sporadically. Again, 0:18:54.480 --> 0:18:57.560 females reproducing on average only once in twelve point five 0:18:57.680 --> 0:19:02.040 years and living for a cinch, are very energy cautious 0:19:02.240 --> 0:19:05.600 and limit their movements to the minimum. It's a different 0:19:05.680 --> 0:19:08.399 kind of animal life to imagine, isn't it like an 0:19:08.440 --> 0:19:12.520 animal that to be clear, it's not incapable of moving quickly, 0:19:12.560 --> 0:19:15.680 like if you try to capture one and it has 0:19:15.760 --> 0:19:19.280 to perform an evasive maneuver, essentially like it's trying to 0:19:19.280 --> 0:19:22.040 get away from you. They can move quickly. It just 0:19:22.080 --> 0:19:27.400 seems like undisturbed in their natural environment. If you use 0:19:27.480 --> 0:19:30.640 the capture recapture method, they haven't moved much after a year, 0:19:30.720 --> 0:19:32.320 after two years and so on. 0:19:33.160 --> 0:19:33.520 Wow. 0:19:33.920 --> 0:19:36.080 The author is also note I thought this was interesting 0:19:36.160 --> 0:19:38.000 that I don't know exactly what to make of it, 0:19:38.080 --> 0:19:41.080 but they say that they have never seen a dead individual. 0:19:41.560 --> 0:19:42.320 Kind of interesting. 0:19:42.920 --> 0:19:46.840 H Yeah. I mean, obviously we're dealing with creatures that are, 0:19:47.040 --> 0:19:50.560 like we said, difficult to observe anyway, and you know, 0:19:50.600 --> 0:19:54.879 we can't count out various other organisms that then scavenge 0:19:54.920 --> 0:19:57.160 a dead one. We also have to take into account, 0:19:57.200 --> 0:19:58.959 you know, the movements of the waters that have at 0:19:59.040 --> 0:20:02.879 least historically been attributed to ones occasionally washing out and 0:20:02.920 --> 0:20:06.840 so forth. And even if one didn't wash out all 0:20:06.920 --> 0:20:09.080 the way to where humans could have observed them, it 0:20:09.160 --> 0:20:12.960 might wash them out to where other organisms would have 0:20:13.119 --> 0:20:17.240 a shot at scavenging them. But still it's an interesting tidbit. 0:20:17.359 --> 0:20:20.000 Yeah, yeah, yeah. To be clear, I don't think they 0:20:20.040 --> 0:20:23.200 meant like humans have never observed a dead one obviously. 0:20:23.240 --> 0:20:25.520 I think they mean like in the in the region 0:20:25.520 --> 0:20:27.800 where they're looking at the live ones, they've never seen 0:20:27.800 --> 0:20:29.840 a dead one there, right right, yeah. 0:20:29.680 --> 0:20:31.199 Yeah, And like I said, that could be because it 0:20:31.280 --> 0:20:34.760 is they do get periodically fleshed out, I'm guessing, or yeah, 0:20:35.000 --> 0:20:36.600 scavengers of one sort or another. 0:20:37.160 --> 0:20:40.480 The author is add a conservation note in their paper, 0:20:40.520 --> 0:20:43.119 which is that the extreme site fidelity of the of 0:20:43.160 --> 0:20:47.000 the olm makes it quite vulnerable to water pollution. You know, 0:20:47.119 --> 0:20:49.960 it changes to water quality, especially like if it can't 0:20:50.000 --> 0:20:52.639 I think, if it can't really migrate very effectively to 0:20:52.640 --> 0:20:55.000 get to a place where there's better water, it's more 0:20:55.119 --> 0:21:01.359 vulnerable to changes in water quality locally. Though. Vulnerability to 0:21:01.400 --> 0:21:04.720 water pollution I think is also true of many surface amphibians, 0:21:04.720 --> 0:21:08.240 who are especially vulnerable because of the permeability of their skin. 0:21:09.160 --> 0:21:12.240 So yeah, another reason why, I mean, not like we 0:21:12.320 --> 0:21:14.520 needed that. Many more reasons why water pollution is a 0:21:14.560 --> 0:21:17.320 bad thing. But here's another one. But final note, if 0:21:17.320 --> 0:21:19.080 you haven't seen a picture of the ulm, you should 0:21:19.119 --> 0:21:22.320 look this one up. You want to see this flesh. 0:21:22.480 --> 0:21:24.600 Oh yeah, absolutely, it's a very it's. 0:21:24.440 --> 0:21:26.200 A very Cronenberg biodesign. 0:21:28.240 --> 0:21:30.119 Yeah, they're like I say, they're a little creepy, a 0:21:30.119 --> 0:21:44.480 little cute. They're very unique. All right. I want to 0:21:44.480 --> 0:21:48.200 get into a topic here that that came up early 0:21:48.240 --> 0:21:50.359 on in my research and a paper that came up 0:21:50.359 --> 0:21:53.200 pretty early on in researching these episodes, and it has 0:21:53.280 --> 0:21:57.800 to do with intra gilled predation, that's the killing and 0:21:57.840 --> 0:22:02.120 eating of potential competitors with any ecosystem, which is apparently 0:22:02.160 --> 0:22:04.639 a pretty big deal in the food chain of the 0:22:04.680 --> 0:22:08.560 Hypogean world. So, as we discussed in previous episodes and 0:22:08.720 --> 0:22:11.560 specifically in the last episode, you know, bat guano is 0:22:11.640 --> 0:22:14.520 kind of an alternative sunlight that forms sort of the 0:22:14.560 --> 0:22:17.159 base of the subterrane and ecosystem a lot of the 0:22:17.200 --> 0:22:20.280 times as bats roost in the cave and defecate, thus 0:22:20.280 --> 0:22:23.359 bringing new resources for various organisms to feed on, which 0:22:23.400 --> 0:22:27.680 in turn feed other consumers. And as discussed in a 0:22:27.760 --> 0:22:31.679 twenty twenty one paper published in Scientific Reports by param 0:22:31.920 --> 0:22:34.920 Mutchova at all quote the food web in a subterranean 0:22:35.000 --> 0:22:39.240 ecosystem is driven by introgild predation. So in this paper 0:22:39.280 --> 0:22:42.160 they drive home some of what we discussed last time 0:22:42.200 --> 0:22:46.719 that quote, detrit us based food webs are prevalent in 0:22:46.800 --> 0:22:50.160 cave systems. Though you do have cases where again sunlight 0:22:50.320 --> 0:22:55.040 enters cavern openings or through other fissures, and also have 0:22:55.160 --> 0:22:59.800 situations where some manner of chemo autotrophy is taking place, 0:23:00.760 --> 0:23:03.720 but still, you know, it often falls to back guano 0:23:03.960 --> 0:23:07.000 as well as other transportation networks for dead plants, and 0:23:07.040 --> 0:23:11.720 to try it as such as the gravitation pawn or streams. 0:23:12.040 --> 0:23:16.879 It's like a like a steep sinkhole situation percolating water. 0:23:17.160 --> 0:23:21.359 And also animal cadavers, the animal cadaver being something that is, 0:23:21.440 --> 0:23:23.400 you know, the animal has gone in there and died 0:23:23.560 --> 0:23:27.520 or something has brought the animal couldaver into the cave generally. 0:23:27.560 --> 0:23:30.199 So that's a good list. So, as you said, there 0:23:30.240 --> 0:23:33.440 are places where the sunlight it's in chemo autotrophy would 0:23:33.480 --> 0:23:37.120 be an alternative to photo autotrophy. You know, mostly we're 0:23:37.359 --> 0:23:40.760 on the on the surface. The autotrophs are making energy 0:23:40.800 --> 0:23:43.280 out of sunlight, but it can also be done with 0:23:43.359 --> 0:23:47.640 certain types of chemicals in the darkness. And then as 0:23:47.640 --> 0:23:51.320 you said, back guano, and then just basically various ways 0:23:51.320 --> 0:23:53.840 for stuff to fall into the cave or be brought 0:23:53.880 --> 0:23:54.960 into the cave that could. 0:23:54.800 --> 0:23:58.480 Be eaten, Yeah, falling in and potentially flowing in in 0:23:58.520 --> 0:24:00.960