All the Times Mammals Went Back to Sea- From Walking Whales to Running Seals! GEO GIRL
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- čas přidán 30. 07. 2024
- Ever wonder how whales, dolphins, seals, walruses, and manatees went from land to sea? This video covers the major groups of marine mammals and the progession of key species in each group during the transition from being terrestrial to aquatic animals. And you will NOT believe how many independent times mammals evolved to go back to sea! I know because I couldn't believe it either! I hope you enjoy learning about marine mammals evolution as much as I did! ;D
References: Earth System History: amzn.to/3v1Iy0G
Uhen, 2007: review over marine mammal evolution- doi.org/10.1002/ar.20545
Berta, Sumich, and Kovacs, 2015: Marine Mammals: Evolutionary Biology- amzn.to/41fEsUd
0:00 All animal groups have gone back to sea
0:51 Marine Reptiles
2:26 Aquatic & Sea Birds
2:43 Marine Mammals
3:59 All Mammal Groups That Went to sea
5:35 Whales Journey to Sea
9:26 Manatees & Dugongs Journey to Sea
11:44 Seals & Walruses Journey to Sea
15:06 Polar Bears & Sea Otters
16:43 Coinciding Evolution of Marine Mammals
17:30 Future of Marine Mammals?
GEO GIRL Website: www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, & donate to support the channel if you'd like!)
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“Many were increasingly of the opinion that they’d all made a big mistake in coming down from the trees in the first place. And some said that even the trees had been a bad move, and that no one should ever have left the oceans.”-Douglas Adams
Yes! Perfect quote.
Please review Dr Behe's Irreducible Complexity theory. Thanks.
Aquatic sloths actually make a lot of sense. Even the ones we have now seem pretty well adapted for life in the water considering they’re great swimmers and can hold their breath for longer than dolphins.
I'm sure the aquatic sloths died from going under water and being too lazy to rise for air.
Such an exciting topic! 😊 I find it interesting how Aristotle already observed in his own time that whales differed from fishes in feeding milk to their young and having to go to the surface for air, but it was not until the 1700s with the fifth edition of his book that Linnaeus created the category of _mammal_ and said that whales belonged to it. 😊
It makes sense that polar bears are a recent development as they are still semi-interfertile with brown bears both in captivity and in the wild.
Did you hear that a group of seals started their own Wikipedia? They called it Pinnipedia.
Wow that's so cool, I had no idea it was that many times. I wouldn't want to be in the ocean with a fully aquatic polar bear, that would be way scarier than a shark!
A shark you can punch in the nose and scare him off, but a polar bear? No way!
Although not back to sea but still back to [semi]aquatic life, I would have liked to see other lineages such as platypus and fluvial hyrax. Nonetheless, a very interesting presentation, as always: you excel. Many thanks.
Good work! The relationship of Behemotops to other Desmostylians definitely deserves its own video.
Oh sweet, great to see you again, Geogirl. I think I am going to go back to the sea as well.
Gotta love the way pinnipeds just rolls of Geo Girl's tongue,
I really love your content! Its always fascinating and exciting!!
Thank you so much! :)
Thanks for another interesting video.
I had noticed the early Eocene, about the 50 my mark, was an event of aquatic evolution for the two groups, but also as interesting the end of Eocene to Oligocene was another. I wonder if there was some global climatic or tectonic influences? I’m sure environmental factors were key.
I hope someone is around to experience a more aquaticly evolved polar bear and hope it doesn’t go the way of the aquatic sloth.
Thanks!
Consider also the recently extinct sea mink (Neogale macrodon) of the New England Coast.
It's not just the sea otters that are semi-aquatic - all the otters are. You are quite correct, though, that only the sea otter went back to the sea - most otters live in freshwater. I'll also mention that the picture of the otters at around the 18 minute mark are not sea otters, but rather some kind of river otter.
It's known that the bear family are related to wolves and dogs. (genetics)
I could definitely see some of the carnivore sea mammals coming from that lineage.
Also as far as I've heard polar bears and Grizzly bears are very closely related.
so much so that they are known to inter breed.
The alternative might be that Polar and Grizzly bears, end up sharing the same land and become a single species again.
How that might shape a future Bear species is also very interesting.
As always great video keep it up ❤
Wow! Another great video. Thanks.
Another great video 👍
This is mostly why I enjoyed the second avatar. It was a lot of "what if Mesozoic marine animals came from a line of hexapods?"
You left out the freshwater mammals - several rodentia (beavers, nutria, muskrats, ), but make a token mention of Hippos... but included the river manatees (and glossed right past the river dolphins).
Also note: Usos arctos is hardly afraid to get wet... at least not the Kodiak (Ursos arctos middendorfi), Aluetian (U.a. gyas), and Alaskan Grizzly's (U. a. horribilis sub-pop). Note that the Aleutian (or peninsular or coastal) Brown is spread from a mainland peninsula through the islands out to Unimak Is; that area does not get ice-capped (but does get some NASTY weather), and gyas may be a contiguous spectrum with middendorfi. Gyas range pretty much requires ocean crossing and seasonal shoreline feeding.
Also, hybrid Ursos arctos horribilis and Ursus Maritimus have been confirmed since around 2016 by Ak Dept. of F&W, and more widely accepted since 2021... as more and more have been seen, and more and more efforts to sample. What hasn't happened is a consensus on «grolar» or «pizzly»...
Amazing videos!
There are still many things to learn.
Thank you very much. I learned a lot of new stuff!
11:50 Fully agree, pinnipeds are adorable. In fact I'm convinced that that Enaliarctos picture must be inaccurate, because I can't believe all of its descendants evolved cuteness independently.
Otters are mainly a river animal with the ability to cross between river systems. Another developing aquatic group is rodents such as beavers and capybara.
They were like, "this land thing sucks, we're going back."
I didn't even think about 7 (!) independent aquatic mammal trips.
I know! Isn't that crazy! :D
It has been hypothesized that humans went through a semi aquatic stage in their evolution. This would explain why we have little hair on our bodies, why the hair we do have seems to grow in patterns that follow the flow of water over our skin, and why we like being in the water so much more than most other primates. It's a fact that many groups of human ancestors lived close to water and got most of their food from there, but it probably has more to do with our talent for exploiting very varied environments than any true adaptation to aquatic life. Barring more direct evidence in its favor, I think that hypothesis is no longer taken seriously.
You are a fool.
Have you heard about the aquatic ape hypothesis? It's a hypothesis that at some point in the evolution of humans, we began to adapt to a partially aquatic environment. It's been 30 years since I read the book, but going from memory, the claim is that the reason why we have blubber (fat spread under our skin all over instead of just concentrated in our bellies), aqua-dynamic hair distribution, we are born with a diving reflex, why we have flat paddle-like hands and feet, and so on, is because at some point our ancestors lived much of their lives in water and began to adapt to an aquatic environment. It's even posited that our upright posture may have adapted to allow us to wade in water, and that our ability to control and hold our breath may have later on helped us adapt to speech. If we were in warm equatorial waters, it could also explain why we lost our fur. That stage of our evolution must have been before our ancestors moved to the savanna and became hunters who would out-walk our prey, perhaps injuring them first by throwing a stone or spear at them, then cook them before eating them. We may have learned some of those hunting skills by spearing fish in shallow waters and using stones to break open shellfish.
Thanks!
2 questions: (a) You seem to use the terms "marine" & "aquatic" interchangeably, which is okay in this context; but more generally, I am intrigued by the existence of various animal taxa (mammals & otherwise) that have both marine & fresh-water species. Otters are a clear example. Not sure if there are fresh-water bears. But there are also reptiles & amphibians some of whom are adapted to each of the two aquatic environments, e.g., turtles, snakes, & even crocodiles. Is there an overarching story of how (say, which direction?) these transitions occurred, comparable to your mammals' return-to-the-sea saga?
(b) How did hyraxes get to be cousins to elephants? Are their marine counterparts in between them?
Okay, thanks for your time, and for always being fascinating. 🐘🐋🐬
I think you get two modes. One is fresh water adaptation to sea water. This comprises most cases. Particularly turtle, lizards, snakes and most mammals.
Then with birds it seems they go from sea birds eating fish to ocean going. Maybe ducks have gone fresh water to salt water?
I’m sure many of the marine mammals went straight to the ocean and what caused it was the food source. Did they discover a marine food source before evolving an aquatic form?
I think it’s hard to tell for cetaceans since their beginning is way back in the Cretaceous. But hippos are aquatic and fresh water and their closest ancestors. I wouldn’t be surprised if they were just everywhere. The sea just encourages a fully aquatic lifestyle.
There are many mammal species that adapted to fresh water life.
Mammals actually are rather suited in general to aquatic environments. Their blood holds more oxygen than a standard reptile and they already adapted to live birth. A fully marine reptile needs to evolve live birth before it can live a fully aquatic lifestyle. Mammals can skip that step since it’s baked in.
Currently, sand nesting species are having a hard time. These are problems that their mammal counterparts do not share. Although I’m sure humans impact marine mammals as well.
oh totally didnt know about aquatic sloths 😮😁
Thats soooo cool ^^
Agreed!! ;D
Polar bear with a shark fin would be pretty cool.
3:55 I thought it was 3, but padded my guess with 5.
Great minds think alike 😅
Seems like sloths were very successful and diverse at one time, would probably make an interesting video itself.
good show
I tend to queue up responses and then delete them without posting.
Very informative video about an objectively hilarious topic. Every so often some mammal becomes a whale.
Lol so true!
wow that was really interesting although I don't really think of polar bears as aquatic at this point, I can see where it would be the very early stages. I can't imagine they will manage to survive however, as they are so enormous that there are very limited environments where they can survive "in the middle" and these environments are in the middle of collapsing. Otters I think have a better chance of moving gradually out and then growing in size after becoming more fully aquatic.
They are adapted to hunt seals when they stick their heads out between ice flows to breathe. Seals eat fish. So Polar bears spend most of their time on ice, and will dive into the water to catch a seal or maybe a large fish, or even maybe even belugas, but I'm not sure. They tend to go hungry in the summer when there is no sea ice.
@GEOGIRL - It is not clear to me why this video doesn't cover both marine and fresh water mammal species, since they are both aquatic. Does it exclude animals like beavers because their diet is terrestrial?
Thanks for an interesting video. I wonder if there are other mammal groups that returned to fresh water, other than beavers and otters. Do you know anything about this possibility? Are hippos considered aquatic?
Hippos, platypuses, water rats, muskrats, water chevrotains and minks can all be called freshwater mammals but they're also semi-aquatic. However, there are some fully aquatic freshwater mammals such as the Indus river dolphin, the Ganges river dolphin, the recently extinct Yangtze river dolphin and the Amazon manatee which evolved from marine ancestors. There's also a freshwater species of seal (the Baikal Seal) and a few populations of harbour seals which live in freshwater like those in lake Iliamna.
You got me too. I would never have guessed Sloths ever were aquatic. Penguins giving up flight to live and swim in the cold Arctic Ocean seems to me to be a weird adaptation. I have to wonder how bad things were to change your home for that lifestyle. ? .lol Too many Great Whites at the Beach ? When I look at all the unusual, strange and weird adaptations in evolution , I have to wonder if Lamarck was smarter than I thought? Thank.. fun topic.
Platypus sits in the corner, forgotten...
This video just covers marine mammals, not freshwater, but I hope to do another in the future about them so don't worry ;)
@@GEOGIRL That's alright. There are freshwater dolphin species as well. It was a very informative video though! ♥
Good Morning =o)
The part where you said these lineages probably became semiaquatic to exploit new resources reminds me of the saying,
*Nature abhors a lunch going uneaten.*
Another species of sea-going semiaquatic reptile is the marine iguana of the Galapagos islands.
So, within artiodactyls, it’s happened twice. I mean, hippopotamus means ‘river horse’.
5x5 Datil NM USA thanks Geo girl
I wish there was a way to predict future evolution. I was reading a book last night about the limits of knowledge, and there was a chapter in there about chaos theory, which makes it impossible to predict the outcome of complicated systems, like evolution, and the weather, very far into the future. That's kind of a bummer. I guess we'll need a time machine.
About aquatic sloths, the Wikipedia article is very detailed and include many references for the curious en.wikipedia.org/wiki/Thalassocnus
Rachel! Africa is breaking apart! What are we going to do? (That's an interesting topic for a future video)
I would say it happened 7.5 times. There's the marine otter (Lontra felina) which lives off the coast of Peru and Chile but it's more closely related to the American river otter than it is to the sea otter. And I would say 7 and a HALF because even though it and the sea otter entered marine systems independently, they inherited adaptations for a semi-aquatic lifestyle from a common ancestor so it's a grey area as to whether you want to call it an "independent" event.
But something I'd like to add: usually when we think of prehistoric sea monsters we think of giant pliosaurs or mosasaurs from the Mesozoic yet some Cenozoic marine mammals like basilosaurus, livyatan & pontolis would give them a run for their money.
Havent finished, but what about beavers?
Are you, as a person, modest / self-conscious? You have worked and studied relentlessly (apparently) to be able to present these information-packed videos. You are quietly and simply awesome, so if any feedback is making you second-guess yourself, be aware that the person is either mutually well-educated, or is displaying a great dearth of knowledge. They are equal to or less than you. Personally, I thank you for your posts. You're very interesting and an engaging host.
Interesting as that was, Feeling a little cheated I don't get to swim with ocean sloths.
Same!
What about beavers, hippos or platypus as you include semiaquatic?
Fascinating!! In fact, according to one interesting theory there might have been an eighth time: *us.*
Just look at the skin, between the base of our thumbs and forefinger; doesn't it look suspiciously like it's an evolutionary remnant of something, that would have resembled webbed skin? Perhaps, at the road from Australopythecus to Homo, there was a marine stage, which might have lasted a few hundreds thousands of years, approximately 3.5 million years ago or so. And perhaps this was when our genus had lost most of its fur, too.
Cool video. Isn't it grizzly bears that polars bears can hybridize with? It's neat to be around at the same time as a species ... a group? lineage? thing? ... is just beginning to differentiate.
a polar-bear grizzly-bear hybrid is called a pizzly
Wait, did Pinnipeds go "back to sea", or are they just beach bums?
What about this particular niche prevents it from being filled by a large fish or something evolving from fish?
It is being filled by something evolved from fish.
actually the ranges that polar bears live is growing not shrikning and they are moving to more siberian/canadian tundra. this might mean that are more on the way to moving back onto land than into water.
Essential reading :
Steve Jones, 'Almost like a Whale'
There's a lot behind the way we group the animal species over time in this video. It's all good. I'd rather watch than not watch. I'm just curious about the attribution in case I repost.
This line of posts is great, Geo Girl. OTOH, this new AI-based text completion is really bad. Am I the first to say that? I could spend all day posting what I was trying to say and complaining about what my AI wanted to change it to. WTF I can't even change the wording of this post without AI wanting to make it different. God help us
Mammals going back to the sea is interesting. I'll cut my comment short and just watch.
Has anyone looked into why amniotes keep spawning fully or partially aquatic lineages? Aside from Sharks, it seems like marine ecosystems have always been dominated by megafauna with lungs since the early Triassic.
I remember seeing something on all-seals evolution. Something like, true seals went back to water and stayed, the sea lions and other non-true-seals did a back and forth between land and water, in part explaining why they are much better on land than true seals that are near helpless out of water.
Does someoe have more i fo 9n this. I'm sure i remember at least some of it wrong
So much nicer on the ears than ai generated voices.... Organic.... ❤
Beavers are hoping to join this list, it seems. They at least swim out to islands already.
Imagine if beavers become fully aquatic mammals with construction skills. If they become intelligent, they could build underwater cities.
What about platypus?
Interestingly, we are the only primate with aquatic adaptation
Two you forgot: the marine otter and the human (though not all humans are aquatic).
The sloth was a bit too slow in the water.
sticky-outy ears
Mosasaur in Avatar, yes
although fully half the movie is just "hey look at the expensive graphics we made!"
@@tomholroyd7519 Haha I totally agree, but I was so happy to see the mosasaur and plesiosaur like creatures that I was okay with that! ;D
🎵Penguins and Puffins and whiskers on kittens🎶….
So, Rachael, did you love the Mosasaur clone in Jurassic World?
Of course! I always love any attention movies give to ancient creatures that are not dinosaurs haha ;)
So beavers are from castoroides which is part rodentia? Muskrats in the same family from rodentia? Then the platypus is from the marsupials, which split from something. Now I've got to do some digging. Thanks Geo Girl 🙄😉😊
Since polar bears are so young, I wonder if humans had any influence on their evolution.
Either you have to include birds in the reptile group or you have to abandon the group of reptiles all together. You can't have it both ways.
Where do Beavers fit?
Rodentia!
@@olecranon They were not mentioned in aquatic families, were the. Aren’t they more aquatic than Ice-bears?
Yep! Beavers and nutria are also semi-aquatic, but in freshwater, so they technically are not marine mammals. But maybe in the future I'll do one about the freshewater groups! ;D
Is the Polar Bear considered a Marine Mammal?
This is totally unrelated, but something has been on my mind, and I can't think of anyone else who might know. Last summer, my daughter and I were breaking open rocks, cause, you know, who doesn't enjoy that activity? But we kept finding little yellow balls inside the rocks. They look like little spherical compacted balls of pollen or something like that, about the size of a b.b.. Do you have any idea of what this is? If anyone sees this comment, I would be so grateful for some information on this. I even have a short clip, showing it, if that helps.
Questions:
1- where were these rocks, what location roughly?
2-were the rocks loose like in a riverbed or attached to a rock outcrop?
3- were the rocks you broke open layered? Hard? Easy or hard to break?
4- did they break into big chunks or flattish chunks?
This info will help people give you ideas of what you were seeing. Breaking open rocks may be indicative geologist potential in you & your kid 😊
@@barbaradurfee645 I actually have like a 9-second video clip of it. If I post the video, could you take a look at it?
@@barbaradurfee645 I posted a video on them if you'd like to see these things.
I consider pinnipeds to be fully aquatic
😎
If polar bears are considered aquatic, then moose should be too, right? One of the top five predators of moose are orca.
Beavers? Or are fresh water amphibians out of scope for this video?
Great question! Freshwater aquatic mammals like beavers and nutrinas were not included since this was about marine mammals, but I hope to eventually find some info on the freshwater mammals and maybe make another video! ;)
I AM HIGHLY OFFENDED!
I went back to the sea the other day and did not receive recognition in this video.
I am so sorry, I’ll make a new video with you included ;)
@@GEOGIRL Thank you!
@@GEOGIRL
My time to shine!
Gimme a headsup though, so I can find my cleanest turtleneck before your hair and makeup crew get here.
I want that au natural look, if possible.
And where do the beavers belong in this story?
Great question! Freshwater aquatic mammals like beavers and nutrinas were not included since this was about marine mammals, but I hope to eventually find some info on the freshwater mammals and maybe make another video! ;)
Fully aquatic polar bears, post climate change, is an uplifting idea. Life finds a way.
I know right! :D
Evolution does not work that fast mate.
@@a.randomjack6661I think even right now, polar bears which are better swimmers get seperated from the rest. evolution always happens, but I know what you want to say. The fact that they can swim better may not save them from extinction...
@@Floyd_Rose94 Usually, nothing bigger than a Kg or 2 did not survive the 5 mass extinction.
For instance, we evolved from sort of rat that survived the dinosaur extinction event.
Some avian dinosaurs also survived. SQARK! (I'm feeling "super-symmetric")
Have a nice day ✌
@@a.randomjack6661 That is right in a way, but that was not the point. Like geogirl said in the end of the video, maybe in millions of years we could have fully aquatic polar bears. There is pressure to survive, so individues that are better swimmers are more likely to become fully aquatic. You dont need a mass extinction for evolution to work. But after such event there is some kind of spread in diversity (which also needs millions of years). You need time, pressure and random but suitable mutations for evolution to work. In this case the weight and global mass extictions are ignorable.
Shouldn't this list include aquatic mammals that only live in fresh water like the heavily aquatic rodents, the hippos, platypus and shrews? And there was Casterocauda during the Mesozoic. So aquatic mammals started way befor the exitinction of the dinosaurs. And do we know if the early ancestors of land animals lived in a marine coast environment or maybe an river deltas in brackish water or in rivers? Because Tiktaalik looks to me more like a swamp dweller maybe going after insects above the waterline.
Pakicetus is considered to be the ancestor of whales. What is the ancestor of Pakicetus? There's 15 million years from the Kpg extinction to Pakicetus. What was going on evolutionarily speaking from the proto-archeocete point of view?
I just stumbled across this new video from the "History of the World" channel ( www.youtube.com/@HistoryoftheEarth ), Rachel and it's about what caused the Cambrian Explosion ( czcams.com/video/kO2hSKLuFNs/video.html ). This guy has done some very good science videos and IMO I think that "Cambrian Explosion" would be an awesome name for a rock band.
More corrections:
Hippos are not ungulates. They are mesonychids (big teeth, yet herbivorous). BTW, look for videos of hippos communicating underwater. That trait was retained in singing mysticetes.
Pakicetus was not an ungulate. It was a tenrec. The confusion comes from tenrec ancestors, anagalids and extant sengis, which have ungulate-like ankles without hooves.
Desmostylians are also not related to sirenians + elephants + hyraxes. They were indeed independently aquatic, derived from hippos.
Pinnepeds evolved from wolverines (Gulo) and short-faced bears (Arctodus).
Puijila is a sister to oligos (Bassaricyon) and these gave rise to polar bears and black bears.
Bears are not monophyletic. Instead several clades gave rise to large, bear-like taxa.
Sea otters arose from weasels (Mustela)
These results come from testing a wider gamut of taxa (2306 at last count).
Your presentation is excellent. Unfortunately, current college textbooks need updating.
Thanks for the updates! Love to see the evolution of our understanding of these phylogenies! :D
Wonder why it would be advantageous for true seals not to have ears?
Well they have ears but not ears that stick out (sorry, I should’ve been clearer about that) ;)
Plesiosauruses like yummy fish, so throw them some! Please please the plesiosaurus.
Or is there just a plesiosaurus who's first and last name are both "Please" -- Please Please the plesiosaurus?
You forgot many lineages, like Platypuses, Beavers and many other rodents, some marsupials, Proboscideans and other Afrotherians (other than Sirenians and Desmostylians... )...
so true seals are sealed at the ears??
sorry ill see myself out
Um,,,hippos?
Wherefore by their fruits ye shall know them✝️
Should be "fok-i-day" I think? No soft c in Latin or Greek.
Mermaids? I'm not saying that I think they exist, but there doesn't seem to be anything intrinsically absurd about the notion of Homo Maritimus.
Unfortunately there is not any evidence for that. Dolphins are the closest thing we got. Also, sirenians inspired the memaid leyends,