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Kamaitachi42 t1_iy5jd5g wrote

Reply to comment by Lithuim in ELI5: why fish can’t breathe in air despite air having plenty of oxygen by CR1MS4NE

Alright I'm really curious, what are the creative solutions?

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Lithuim t1_iy5thqg wrote

Mudskippers have more rigid gill plates that don't collapse, and do the whole "breathe through my skin" thing that frogs do too.

Bettas have an organ called the "labyrinth" behind the gills that they suck air into like a false lung and then bubble out later.

Corydoras Catfish eat the air and absorb oxygen in their digestive system.

And of course lungfish are close relatives of our own ancient ancestors and straight up have lungs, but decided against the whole land thing.

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TheRealOrous t1_iy81zfq wrote

>"breathe through my skin" thing that frogs do

Huh. So Kojima didn't make it up entirely out of his imagination, that's interesting. I assume there is something that would stop it working with a human though, right?

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Lithuim t1_iy83i6v wrote

Two things

First, humans are simply much larger and heavier, and have much more mass per surface area to try and oxygenate - and it must travel much farther to reach the critical organs. It’s not a very efficient system so most amphibians are very small and many supplement with lungs, gills, and/or tricks to increase surface area.

Second, if you’ve ever met a frog you may have noticed that they spend 99% of their time motionless staring into the abyss. They’re cold blooded and have poor oxygenation capacity, and so have very little metabolic energy reserve to spend. They move infrequently and tire quickly. Humans are tireless hyper-endurance athletes by comparison. We can move all day and burn oxygen at a much faster rate - but need much more food to do so.

That’s one of our evolutionary advantages, even by warm blooded mammal standards humans are tireless athletes. We’re not the fastest or the strongest, but we can pursue for hours like a horror movie slasher until any prey is absolutely gassed.

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TheRealOrous t1_iy8la07 wrote

Thanks for the knowledge friend! I suspected that it was something to do with our warm blooded nature, nice to see it as a side by side comparison.

One last question, what sub section of learning gave you this information to so readily share with me?

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Lithuim t1_iy8n7fm wrote

A fishtank full of rowdy corydoras catfish! …and a background in chemistry.

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