The Amazing Biogeography of Caves 

Minecraft reference

yeah best minecraft update

Truly mindblowing in comparison to the generation before. I mean just the damn size of things (X_X)

Lmao great and true comment

​@@Rich79yeah

Another way to look at it, which is probably more likely in most cases, it’s a waste of resources investing in eyes. They’re not losing it so much because they don’t use it, but because they don’t use it it’s not worth investing energy into those organs. So the animals who have less developed eyes are better utilizing their energy demands and have a competitive edge over animals who are putting energy into their eyes, so then it becomes a selective pressure to reduce the eyes.

Precisely ​@@TheBrewster320

Waste of energy to grow eyes too

I am afraid your professor was wrong there: simply not beneficial (unused) traits certainly can and have disappeared due to genetic drift.

Yeah, getting eye infections may have resulted in some individuals being removed from the gene pool before they could breed, but it's probably only one small part of the picture. In other environments, if a salamander didn't have eyes (to see and catch prey), it would starve. In a cave, eyes are useless in finding prey, and thus evolution will not select for the development of eyes in a cave environment. If any animals still have eyes, it's just a vestigial feature. Also, there is sexual selection. If all the animals are blind, they won't care about what their mate looks like. That's one reason why you see some pretty freaky looking animals in pitch black environments, like the deep ocean, whereas you'll see beautiful birds in bright, colorful rainforest environments. @@rathalos1522

I know surface level wasn't a joke. But I like to imagine it was. Otherwise very insightful comment.

@@josephrion3514AAAAAA b by NU and

That's normal way of rationality 😅

Most mammals, bats will quite happily live in caves.

Cavemen.

❤quality answer.

This makes so much sense, I was wondering why there are no cave turtles, as they are also ectothermic and amphibious so in theory they could fit in this particular niche, but if they prefer warmer temperatures than salamanders, it factors them out.

I wonder why there are no cave frogs though or cave caecilians for that matter

@@thedarkmasterthedarkmaster Caecilians biogeography I don’t think lines up well with where most cave systems are as presented in the video, but also we don’t know enough about them as a group anyways. I would not be surprised in the slightest if a cave dwelling species eventually was found in a cave system in the tropics. I think they’re arguably even more well adapted for caves than salamanders (other than cold tolerance, but probably isn’t an issue in tropical cave systems). As for frogs, compared to salamanders, frogs are much more visually based hunters with the exception of fully aquatic species. Salamanders can be visual hunters but many, especially aquatic salamanders, are far more dependent on scent, though aquatic frogs are also scent driven. My guess though is being so sight oriented it may play a factor. Also, the aquatic lineages I’m aware of may fall into the same case as the caecilians. Off the top of my head I thinking mostly southern African and South America for fully aquatic species who would probably adapt well to cave life… if they had access to said caves.

Another point in favour of salamanders is that all highly specialised cave species are extremely neotenous, which adaptations are found in aquatic salamanders such as the axolotl. For other animals to reach their level of energy efficiency, they would have to change even more drastically. Cave salamanders look the most like the earliest amphibians that walked on land.

Agreed. Also most of these cave systems seem connected only by underwater sections, so any animal that can't go through long periods of time underwater will have a much smaller area to colonize, making a breeding population much harder to maintain. Salamanders, by being aquatic with high tolerance for damp areas, seem uniquely suited to many cave systems. The area that really intrigues me though is southeast Asia, which has both some salamanders and a lot of karst terrain, including some of the world's largest caves.

@@rianfelis3156 exactly. The Edwards aquifer is a great example. HUGE water table with extensive fully submerged passages too small for most large fish species, but passable to the usually skinnier salamanders.

@@rianfelis3156 the existence of Giant Salamander species in China and Japan has it’s own exceptionally interesting possibilities too. Imagine… a subterranean morph would probably have to be smaller, but it could still be quite large.

What a simple yet brilliant answer... simply asking "what kind of animal could get through an underwater passage?" solves a lot of the mysteries about why there aren't mammals or frogs.

Your comment made me think that maybe that's why we see every completely adapted cave salamander retain their gills (the little feathery things on the side of their heads) It varies from one species to another but as far as I know most salamanders are born as little tadpole-like larvae who have these gills up until their adulthood, where they lose those gills and develop lungs (meaning they can drown underwater) And since caves can get completely flooded it would be much better for the individual to just keep the gills on throughout their whole lives For example at 11:51 you can see that this species which is in the process of becoming fully cave dwelling hasn't yet evolved to keep the gills on their adulthood But the fully cave dwelling species like the ones at 16:27 do seem to keep their gills

I looked it up! Movile cave in Romania! The ecosystem is based on chemosynthesis and similar caves exist in Palestine, Italy, Greece, Iran, the United States, Mexico, and areas in the Caucasus!

@@kennethschick4304 great job! If there are more... more chances for a video in this channel! BTW: thank you

@@kennethschick4304 Nice pull. Apparently methanotrophs convert methane there into the carbon nutrients. I wasn't able to find what converts the high CO2 (100x atmospheric level) to O or how O incorporates into nutrients.

​@@pablorey9203wgwzwz4,qc1cF1Cfex:_hfyv2mwcYv52-I5crc:

There’s things like this in deep ocean geothermal vents too , and cold seeps

What of mineral deposition

@@thedoomofred5174that would mostly happen underwater, so unless they're aquatic, they would likely never know about that

What if one challenges the belief of everyone getting smaller and the exile him and generations later they see he was right 😂

@@robertosalazar3255 galileo type situation

True. Also I wonder how the whole biogeography of caves looks like if they are connected to the ocean instead, like the huge network under the yucatan.

@@sizanogreen9900 From what I've seen and heard about caves in the Bahamas there can be sponges at the Oceanic inlets that go a far bit into the cave systems and the salinity of the caves changes depending on your proximity to inland versus oceanic inlets. I know that's a similar case here in Florida and that also when these caves do connect with the oceans then they experience shifts in current linked to the tides.

@@Intelligenthumour It really is interesting. I recall it being mentioned in some documentaries that sometimes fishes and turtles wander into those dark caverns. While some are more native there. Pretty much like it is on land, but just with a different cast of animals and maybe niches. I'd like to see that explored as well, but I guess such aquatic caves are even less understood than terrestrial ones...

@@sizanogreen9900 I'd absolutely love to see more exploration of cave biomes. You might be interested in reading up on Movile cave too. It's a cave in Romania that was sealed ages ago and developed a chemotrophic biosphere. It holds animal refuges that have been there since long before the last ice age. It isn't quite the kind of cave you're talking about but it's incredibly interesting. I've had ideas about soft robot based ROVs, a kind of infra-red based trail cam(some materials are opaque to visible light but transparent to infra-red light so it'd be easy to place these with a dull infra-red light source and record animals passing by without interfering with them) and also about the disappearing lake in Oregon known as "Lost Lake" which has lava tubes at its base that drain it when it fills up with melt water. That cave system may very well have lots of undiscovered troglobites that thrive off of the debris carried down the lava tubes.

Lava tubes are essentially cave starter kits. They are too new to be anything of interest to a biologist since they don’t have any unique features yet

Yeah but lava tubes are featureless corridors without vegetation or any other life. Anything that may be found there is using it as temporary shelter so they aren’t really relevant to the topic

@@SerDerpish I don't know about that one. I recall having watched documentaries where they delved into the lava tubes of hawaii and found some rather unique insects at least. Has been years tho so as I said, I'm not sure about that one.

​@sizanogreen9900 they meant typically, because Hawaii is already rather unique as an environment due to it being a volcanic island chain, which leads to caves being distinct in this.

@@mrhalfsaid1389 don't you mean because it is a massive shield vulcano created by a hotspot? There are other vulcanic island chains after all, most less unique than hawaii is,

Caves can form anywhere given enough time. And any cave, no matter the type of rock that it's in, can harbor life. It doesn't matter that karst terrain is the most likely place to find caves. That's like saying McDonald's has all the burgers when other places make them too. It makes no sense. And many lava tubes harbor life and they can last a long time, giving plenty of time for creatures to inhabit them and adapt to their environment. Take for example the planthoppers, millipedes, spiders, bats, etc that inhabit many lava tubes and that have adapted to the environment. They even have bugs named after the lava tubes that they inhabit. The lava tube beetle, for example. Lava tubes are also not featureless corridors. That's far from the truth and lava tubes are certainly very relevant to the topic due to all of this. I highly recommend researching subjects before spouting false information about them. Sizanogreen9900 is right....

Its kind of amazing. Worldwide there are nine taxonomic families of salamanders, of which eight can be found in the SE United States!

The Us has the biggest diversity in temperate plants and animals, which are usually not as diverse as tropical.

I didn't know either until I went to uni for ecology and started working on amphibian research! It's honestly so fascinating, and now I hope to do my master's thesis on cave salamanders

I think a notable difference is the snakes are preying on something that participates in the outside food chain, as opposed to salamanders preying on something that comes from the cave food chain. Theoretically the cave foodchain could start with chemo synthetic microbes that eat rocks/minerals for energy similar to deep sea vents. Don't know if the distinction matters, but i feel it should atleast be mentioned.

Frankly, that sounds terrifying 😅 I'm already scared of caves and snakes (even though I know most are friendly), a cave full of snakes is just about my worst fear

​@@bugjamsI wouldn't say most snakes are "friendly" just "non threatening".

So lake baikal depths are more analogous to cave ecosystemy, than to hafal and abyssal regions of oceans?

he already did an episode on mountains.

He has made one, check it out it is cool too

Yo and look into kea NZ alpine parrot

@@hellfun1337 KyloMOAR.gif

I loved the "sky islands" in Arizona. It is so cool to look down on the desert from a well-vegatated peak.

I was going to mention them if someone hadn't yet

omg i literally just mentioned them in my reply! they have got to be one of the coolest animals in the world!!

just make sure to return to the surface to tell us about them!

@@AtlasPro1 In temperate rainforest of the southern caspian sea in iran there is an almost cave dwelling salamander species and you didn't mention it. Paradactylodon persicus (Persian brook salamander)

just visiting secured and visitor prepared caves is already pretty damn impressive.

Truly a harrowing experience, how quickly everything changes just a couple feet down and in really makes you think about our ancestors and their journeys out

Did you just missed the chance of using the work sepelunking when you could actually used it in a real sentence

I'm not exactly claustrophobic, but I don't like spaces tight enough to restrict movement. That being said, some of the coolest places I've seen in the US have been the sections of caves open enough to run tours. It's nice because it's a bit of a tourist trap, but doesn't feel like it because you're experiencing nature. More like going through a national park than a wax museum

​@@analyticsjunElitists view spelunking as a term that only newbies to the hobby use. Not everyone that calls it caving is an elitist, but the amount of mockery that people get for saying spelunking has lead to caving being the more popular term. Use whatever term you like though, spelunk just comes from the Greek word for cave, so both accurately describe the hobby.

make it catch on!

@@AtlasPro1Atlas pro! Sorry for being a bit too late but I have something interesting I’ve found that you might be interested in I’m the guy who suggested the flightless antsrctic island moth to you a while ago. However, since then I’ve learned that apparently this convergently happens in multiple different species like different types of wasps and midges as well. Even Darwin himself has mentioned this and he hypothesized that it’s impossible for the insects to fly due to the harsh winds, but new research shows it’s possible but quite costly energy wise. Compound this with island effect making insect have less of a need for flight and here you get some flightless insects. There are still predators for insects tho, being birds, thus some have retain their ancestral stingers and some species of wasp even have a flying male and flightless female where the male carry her to flowers to drink nectar as she produce eggs. It’s fascinating! Antarctic islands can also be a good way to either semi-sum up or revive your island series as well.

⁠@@AtlasPro1 atlas pro, pls read this. I just finished the video and I have a lot I really really wanna talk to you about, that might change how you view this episode entirely. As a long time fan of the channel, I don’t wanna use this word, but this video is biased, I’m sure by accident. Your premise is based only on one thing, that there previously mentioned fish and invertebrates cannot be effective apex predators in caves. However, that’s clearly not true and these creatures have replaced the niche of the salamander multiple times across the world. The megalaya cave fish(Neolissochilus pnar) discovered in 2019 in India is by far the LARGEST cave fish if not the largest troglodytes ever discovered, WAYYYY BIGGER than an olm, and they are carnivorous, eating otehr cave fish and cave insects. In other caves, some has air and water conditions that are toxic to salamanders, species like cave centipede have come to fill this niche. In Thailand where I live there are climbing cave fish that can scale waterfalls to snatch food particles and maybe potentially prey, just like a salamander. Your research is well done but please consider factors that might not be ecological, but artificial, as well. as for why there are no cave salamanders where the permafrosts exist, permafrosts means the soil is always frozen. Caves rely on external organic matter to flow in and feed the critters inside that can support larger predators, thus when the debris are blocked by ice, the cave is starved. Also the fact that cave salamanders are only found where there are salamanders is, well, self explanatory. Where salamanders are at their greatest diveristy it is more likely for at least one of those species to end up wandering into caves.

@@thefolder3086 "Please read or else I would be irritated (kinda am now)" That's not a good thing to say to someone when you're trying to get them to listen to you.

@@pendlera2959 you know what , fair enough . I write that when I was kinda mad

Tennessee has some amazing caves. I visited the Lost Sea a few years ago, and I was absolutely stunned.

howdy from ur neighbor in the US state with the longest (known) cave system in the world, kentucky!

Hear hear

I don't know much about these spiders, but being giant, to me, sounds like proof the cave lacks an apex predator to hunt them, rather than proof they became one themselves.

That's a strong possibility. Most salamanders don't disperse very far between generations. Given that the Isthmus of Panama only formed recently, tropical climbing salamanders (genus Bolitoglossa) havn't had a lot of time to disperse across South America from the north.

@@nyon7209 Gigantism can be a response to predation, though.

Yes!!!! I was going to mention this and wondered why he didn't add it to the video. He probably didn't have enough time to add it to the video would be my guess. Editing takes a LONG time for such long videos and I get it. But, a passing mention would still have been cool. It's an absolutely awesome cave system that deserves more attention due to how unique and cool the critters are.

make sure to keep your eyes peeled for any white critters!

Good on you for wanting to do that kinda work. Youd never have to recuse me lol, but someone out there will appreciate your help in the future

@@AtlasPro1 i just so happen to be located where olms are endemic and the density of caves is just absurd so encountering some is very realistic.

makes you think about how some of us lost our skin pigmentation though 🤔

Lol. As an Australian I was looking for this comment. Nulla-bore mate, Nulla-bore.

There are actually cave crocodiles that live in poop water in a cave in Africa. They are called the abanda caves.