Islands That AREN'T Actually Islands 

That makes wonderful sense. Guess we're the greatest predator in the world

I think that's also just humans being good at extincting other animals in general, especially large ones that have not contacted them before. Africa is the only region that still has large numbers of megafauna, and this is probably because they evolved alongside humans and adapted to them, whereas everywhere else had no idea that the funny naked ape was the most dangerous animal around.

yh i think giant ground sloth coexist with humans in south america

@@heichan8657 I am pretty sure those are extinct.

or alternately the worst.

Good suggestion. Probably the stronger pressure is lack of predators, I think food is pretty scarce in the abyssal depths.

Abyssal Gigantism is believed to be an adaptation to both pressure and temperature. The square cube law states that as an object doubles in size, its internal space increases by 8x, and its surface space only increases by 4x. This reduces the effective surface pressure by reducing the surface compared to the internal structure pushing back. It also reduces the loss of body heat by reducing the surface area through which heat can be lost. That's the working hypothesis anyway.

@@wizardtim8573 Thanks for your scholarly input on this question!

Abyssal Gigantism is mostly about efficiency. Because they have so much more volume within them, they retain heat better and are far more efficient compared to smaller counterparts. The channel DeepSeaOddities covers strange critters down there and one of the most common traits among them is Deep Sea Gigantism.

Spider crabs. 😳

I wouldn’t drink from anything that’s non moving.

@@YoursUntruly bikal lake is large enough to have currents

@@YoursUntruly , you shouldn't drink even moving water. In upstream, there can be anything possible like Dead animals, feces, rotten things.

@@Edward4Plantagenet yeah but it’s a way better bet when you’re dehydrated and NEED to drink something, always go for running water.

@@YoursUntruly I live here and you can drink this water, it’s safe. They said some small animals clean it. Japanese people even come here to find out if those animals could clean their water too

Its uluru not ulugru

@@RATSKETCHES Ulurugu is a range in Tanzania, while Uluru is a mountain in Australia

@@RATSKETCHES Imagine trying to correct someone he doesn't know and doesn't know where he lived, spelling it wrong and being in the wrong to begin with.

@@RATSKETCHESIf you know what Uluru Rock is you know where it is, and it’s not Africa.

@@RATSKETCHESdelete this comment it’s wrong

I had decided to shut up about it until he said that baikal seal is the only freshwater seal... xD

Can confirm.

Wait but aren't the Saimaa and the Ladoga just subspecies of the ringed seal? The Baikal seal is a species of its own.

@@TheWoollyFrog He never said species of seal though, he just said seal

@@TheWoollyFrog it's still a seal living purely in fresh water.

Came to the comments to say this, though I couldn't remember the name, and only the general area.

Is that where Mount Roraima is?

At the top of this tepui, the borders of guiana, venezuela and brazil meet. They have different names depending on the side you are.

@@AntonioZL guyana*

@@hoseasylvester2596 It's guiana in portuguese, which is my native language.

…2000 km….

Your*

@@Hunter-jx8jl I fkg knew this reply was gonna come as soon as I read the comment. I was gonna write a more annoying, ironic version of the *your thing, but since you already "uhm achtchually'd" this guy I'm just gonna reply to you instead.

And Borneo too! The Bornean sun bears and pygmy elephants are also examples of insular dwarfism :) Not to mention a close cousin of homo sapiens, another human species, found in the region. What a fascinating place!

One of the richest biodiversity regions too

@@fafddzfaf I'm curious, what other human species?

@@DesertsOfHighfleet it’s something like “homo florensus” they’re related to the dovicidans species of asia

@@DesertsOfHighfleet Homo floresiensis en.m.wikipedia.org/wiki/Homo_floresiensis

Your teacher isn't wrong. Countries are islands too in many perspectives.

en.wikipedia.org/wiki/Island_mentality

Vale la pena mencionar que los animales gigantes se extinguieron en Chile, como en todo América

@@Nickferal e en australia tambien

In spain there is a cabe were albino scorpions live and you cant find em in another place of the world

In Texas there's a group of caves where each one has a some different completely endemic species of spider.

@@orangeoran4020 A lot of caves in the Hill Country have a species of cute (and endemic) axolotls. I’ll also never forget learning that shrimp live on top of Enchanted Rock, that restructured my brain.

I was extremely disappointed at zero mention of caves. Some are actually sealed off from outside life completely, making them more isolated than an island in the middle of the ocean.

Not to mention "Culex pipiens molestus", in the London Underground!

That's sick

One thing that didn't seem to be touched on explicitly in this really interesting vid was the impact of humans, whether predatory or changing the environment (eg through slash & burn) - I didn't know if that was because we've simply been too recent to make a significant contribution to such isolated evolutionary processes...? Aotearoa/NZ is (sadly) a great example of how introduction of humans can cause rapid extinctions of both megafauna and miniaturised species, but do you know if there's anywhere in the world where human impact can be specifically linked to changes in species sizes without actual domestication being involved...?

A pleasant surprise to see you here. Maybe a future collaboration of how much geography has affected politics throughout history and still continues to do so.

​@@OptimisticNihilist15 A collab from Politics with Paint and Atlaspro would be amazingg!

Evolutionary and literal pressure

Cool!

Good call.

As you mentioned though, invasive species have made it appear like the rest of the area unless you know what you are looking for.

@@norml.hugh-mann yeah, it’s pretty neat! 🪨

Taal Volcano is a “Vulcan Point island within a crater lake on the volcano island within a lake on Luzon island.”

Currents carry eggs, larvae etc very far. I don't think many of these places are in effect isolated even though the distances between them can be huge. But i may be wrong!

@@5kunk157h35h17 that's certainly true for small animals that mass spawn into the currents. There could however be instances of larger species found in isolated pockets. I don't know of any but it at least seems possible.

​ @Frank B Yes I think it could happen but I don't see how the main things causing gigantism (untapped resources, lack of predation, lack of competition) would occur in something as connected as the sea. But I don't know enough. I'm just guessing. But if it does happen I think the deep sea would be the best candidate. Deep sea currents are much slower than surface currents. Some isolated parts could possibly be impossible to reach for organisms suspended in them. Quote about currents "Whereas speeds of surface currents can reach as high as 250 cm/sec (98 in/sec, or 5.6 mph) a maximum for the Gulf Stream, speeds of deep currents vary from 2 to 10 cm/sec (0.8 to 4 in/sec) or less."

@@5kunk157h35h17 They can be isolated if the water has a higher salinity.

Very interesting, thanks.

weird that ghost frogs are a thing in mountains in South Africa, they're fairly common on some beaches here in the east coast of the US (specifically Assateague Island I'm not as sure if they're common in other places but they probably are)

@@kevincronk7981 think its probably the case of different genus having the same name, every article I check says there are only species in southern africa and have no related species in North America. Also, had a look at a government website, seems none of the frog species there are classified as ghost Frogs, so could also be a local name.

@@cruz7579 Yeah and the incredible current separates some too.

Marshes would be fascinating to hear more about! There are such weird & wonderful biological things going on in those areas, whether it's critters/plants that bridge both salt & fresh water survival, or species that rely on marsh areas but migrate across enormous distances to complete their reproductive cycles...?

OMG this sounds dope af!

@@anna_in_aotearoa3166 it’s even more fascinating when you consider the lands surrounding them. Wheat, Corn, and soy fields everywhere and right in the middle these little islands of marshlands and one of the few places where native prairie grasses are allowed to flourish

en.m.wikipedia.org/wiki/Quivira_National_Wildlife_Refuge

en.m.wikipedia.org/wiki/Salt_Plains_National_Wildlife_Refuge

It’s probably both.

Need i remind you of Pliosaurs, and Plesiosaurs, Crocodilians Varanids etc.

The argument of heat being a factor isn't plausible. Homeothermic animals (not cold-blooded) want to be warmer, and being larger helps them maintain those temperatures longer so being smaller is not advantageous. Also, they are living in tropical and subtropical environments where heat isn't a factor, they are warm enough to do what they need whenever they want. More likely the ancestral chameleon was already small and these are just a result of a isolative evolution where one species becomes multiple distinct species when one or more population is isolated from the main population. There are other dwarf chameleons that inhabit southern Africa which are related to these montane species. Most likely the environment on these mountains hasn't changed relative to what the ancestral species inhabited. Therefore, there's a lack of change in the amount of dietary stress, which is the main factor related to a change in size. However, predatory or sexual selective influences seem to be present which tends to be the main driver for colour changes as we see in the dramatically different colouration between species.

@@Prospector32 Greetings from Finland. We have some lizards here too and they are very tiny. It is also rather cold here usually. This video showed the "one size fits all" expectation to be a problem when comparing very different things because there are more than just few variables.

You see "rain shadow" effects in most regions. A range of mountains, or even hills, often attracts extra rainfall leaving the clouds empty, which means land on the leeward side of the range gets lower rainfalll than it would otherwise have.

Almost every mountain range and even hills do something similar known as the rain shadow effect. Another good example of this is the Himalayas turning Tibet into a cold desert by keeping the monsoon winds within Northern India and Terai region of Nepal.

@@Dave_Sisson Hey atleast that way you also get rivers, right?

@@thelakeman2538 OK, but I'd assume the drsasticness of of something like the Andes can only be done by mountain ranges like them or the Himalayas that are vast and tall. Simple hills can't wall off that much moisture and if it's a single mountain that doesn't stretch that far the same is true.

yet, there's also the antartandes if they had any opportunity to do so aswell when there was no ice on the continent.

Endhorric lakes also have another resource that increases, dissolved minerals. The catch there is the species need to be able to adapt to those increases. Plants would have the easier time of it, since they are the initial organism in that chain, whereas further up the food chain, those animals require something else to have had evolutionary success, first, which may not always occur.

Yeah especially in the case of large and deep rift lake type environments like lake Baikal you really do see strong parallels between lakes and islands. Though a nuance to account for in discussion of refugia bases island analogs is that prior to the rise of the Andes to their modern towering heights in the Miocene South America was considerably different from today though in some sense it was an island environment of its own in that its fauna ecology were noticeably distinct. Note that in the far south this does not apply to flora the same way specifically for plants which use wind dispersal as the circumpolar jets of the Antarctic have ecologically kept the flora of the far south in genetic contact. The rise of the Andes to their modern towering heights had a profound effect on these South American ecosystems as it occurred fairly suddenly causing the unique species high on the food chain to be unable to adapt leading to the complete extinction of the Sparassodonts(metatherian mammal apex predators) and Sebecids(an ancient lineage of crocodylomorphs that independently survived the K-Pg extinction convergently evolving theropod like jaw anatomy most strongly resembling the tyrannosauridae) and the extinction of the larger lineages of terror birds. AT their prime south American Sebecids reached some of the largest sizes seen among Cenozoic apex predators filling in the niches of the theropods of the Mesozoic so this arguably might be classified as a form of insular gigantism as south America was isolated though ultimately I think this is a poor fit as the larger sizes might be far better explained in terms of the competition among the branches of the South American predator guilds The point is that this meant these and other ecological niches were vacant when the great American interchange happened some ~10 million years later so a resulting key distinction between South America and other refugia island analog environments is that it was primarily a wave of initially generalist species which invaded the continent speciating into these vacant niches effectively trapping those species which specialize into insular dwarfism. In this sense you may have potentially even gotten gigantism but even if that was the case humans kind of ended that when they came to the Americas. At the very least rodents when they arrived in South America by rafting dispersal sometime between 30 to 50 million years ago certainly did

Not completely isolated, however. Even on Manhattan Island in NYC coyotes have been spotted, having presumably crossed via one of the bridges from the Bronx, on the mainland, where they are now more often seen! And before the bridges, maybe some small species floated across, say, the East River on trees branches or debris.

It did exists, the problem was that its consolidation of evolution, as in, when the species started breeding inbetween themselves, was also during the period of extreme hunting during the late 1800s which caused animals to go extint, or in this case, never allowed to settle as species.

I second that! More documentaries about the real life "hobbits" and the related "orang pendak" myths of Indonesia.

PBS Eons have also covered - a channel worth checking out if you haven’t seen it

@@absolutetucker9198 thanks, I've subbed to them, but haven't watched them too much in the past. Will give them another look nowm

It was on the video by Moth Light Media: How did a seal get to a lake in the middle of Siberia ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7GUnQsnLVGo.html

Ice in land?? Impossible!

To tag onto your point, he seems to forget that bull sharks transition between fresh water and saltwater rather often. Granted, sharks are a giant fish while seals are mammals, but I would think it is easier for a mammal to change habitats than it would for a fish.

Yes, and there are othe freshwater seals in Lake Lagoda an some Finish lakes.

What about salmon and some trout and (I think) sturgeon, that are born in fresh water, swim down to the ocean or sea, live to adulthood there, and then swim back upriver to spawn? Okay, they die after mating, but they survive years in the ocean after leaving the rivers of their birth, so adapting from fresh water to salt is a matter of weeks rather than millennia--and they manage the strenuous swim upriver, often or usually leaping up rapids and falls, without succumbing to the lack of salt water; their death after spawning seems to be a part of their life cycle, just as many insects die after mating.

As far as bodies of water go, even the great lakes are pretty small compared to oceans and seas

Those are some of the coolest landforms in the world, he should definitely do a video on their biology

I thought he was going to mention the Cichlids in this video, but maybe he'll do a future video on them

That is interesting. At the same latitude lives the Tasmaian giant freshwater crayfish which grow up to 80 cm long. Not surprisingly they are the biggest (and scariest) freshwater invertibrate in the world.