Arioch wrote:Solemn wrote:The reason we don't still have anything of the sort today, even in Australia? Hemocyanin's kinda not the best thing for moving oxygen around. The Loroi only have to contend with part of what makes Earthly hemocyanin terrible (the way its copper bonds with oxygen); amongst the arthropods, their free-floating hemocyanin isn't even circulated. No hearts or anything. It oxygenates their tissues via passive diffusion, and so their volume is limited by how far a tissue can be from exposure to the air, lest that tissue be starved of oxygen. Turning hemocyanin into a more active transport system has its own problems, though; it's just not all that good at moving oxygen around.
To clarify, insects don't use their hemolymph for oxygen transport, but instead have trachea through which air is delivered directly to tissues throughout the body. It's true that oxygen delivery is the main limitation on the size of insects (and so they got much larger in eras with higher oxygen content), but this hasn't got anything to do with hemocyanin.
There is a glaring, horrifying error in what I wrote there; "no hearts or anything." I either meant "no familiar humanlike heart-lung system in the breathing process," or I just went inexplicably dumb. Both have been known to happen.
Arthropods have hearts. Well, they have muscles that move their fluids around, though if I remember anything correctly at all, they don't do this to actually circulate it (which would involve moving it in a circuit, hence the name), more to keep it mixed.
Not all terrestrial arthropods exclusively use trachea (though, not all arthropods use hemocyanin either, others have come to embrace the Gospel of Iron, though from what I remember they don't use hemoglobin but rather some other iron metalloprotein, hemoritin or hemorathin or something like that, something with an "r," I'd google it but I can't google what I can't spell, some iron-based blood that's wrapped in a corpuscle but which doesn't cooperatively bind to oxygen the way hemoglobin does and which is nowhere near as efficient) so you need to use hemocyanin as an oxygen transport mechanism to support a number of tissues in a number of critters. Insects and their tubes everywhere approach is its own sort of thing, but if I recall, a number of the ancient, very large arthropods of the Carboniferous used book lungs, gills, and other such exchange systems that would require hemocyanin to disseminate oxygen to the rest of the systems, and which would require a significant concentration of oxygen to work at their scale. There are still arachnids with book lungs (which are less like lungs than they are like gills, iirc) rather than trachea, which serve to oxygenate the hemolymph rather than directly feeding each tissue. There are also arachnids with trachea, but, again if memory serves, that was something that likely evolved out of the book lung. So the oxygenation of tissues will still have something to do with hemocyanin for a number of terrestrial arthropods, particularly the book-lunged scorpions of the era.
Of course, a book lung is radically inferior as an oxygenator than a real lung with a vigorous, mammalian heart circulating deoxygenized blood into it and oxygenized blood away, so that doesn't necessarily reflect too poorly on hemocyanin.
However, I do recall a lecture I was given, which stated, among other things, that with an equal concentration of hemocyanin and corpuscular hemoglobin (that is, as many moles of hemoglobin as hemocyanin, with the hemoglobin wrapped in blood cells and the hemocyanin floating free), over a given period of time the hemoglobin would be able to transfer about three to five times as much oxygen per unit volume as the hemocyanin (depending on the type of hemocyanin; certain varieties of hemocyanin are more likely to bind oxygen cooperatively). I don't honestly recall if this was attributed primarily to the hemoglobin's innate chemistry or to it's packaging in a corpuscle, but I suspect it was both, and have been acting from that assumption for a while. ("Hemocyanin has more oxygen binding sites, but is so reluctant to bind cooperatively that it actually ends up moving less oxygen at standard temperature and pressure…" "Octopi are actually pretty close to a similar concentration of hemocyanin in their hemolymph as you have hemoglobin in your blood, and a fair approximation of the concentration of hemolymph as you have blood in your body, and a circulatory system that's actually pretty interesting. The reason they're fine with hemocyanin is because they live in extremely cold temperatures and at pressures where it transfers more oxygen than hemoglobin would; still less than hemoglobin does at stp…" blah blah blah the octopus has three hearts and a gill system that's the envy of the ocean and its hemolymph still doesn't get anything like the blood-oxygen per blood-volume of a mammal, though marine mammals need the extra oxygen to stay warm and have to surface to breathe so it's not like one's objectively more advantageous in all ways than the other in all ways and so on and so forth).
If I've been misremembering that lecture for all these years I'm going to be kicking myself about it for a long time. My memory's far from perfect, but usually it's better than that.
(I'm focusing on the arthropods even though there were a lot of very large and interesting vertebrates in our own Carboniferous, and Perrein's arthropods might have been forced into smaller evolutionary niches by vertebrates and all sorts of things might or might not be. I am doing so because it is funnier to me to imagine cute blue girls messily devouring enormous deadly scorpion-analogues, or creatures that superficially resemble the Umiak, or any number of carapaced nightmares, than to imagine them eating vaguely reptilian steak. And far,
far funnier to imagine them trying to share this with Alex. "Just try it. Only the top four sets of mouthparts are venomous. And it really
is dead, they all keep twitching like that for a couple of hours after they go. It's chemically pretty similar to your rations, it should sit fine with you, I swear.")
Arioch wrote:Solemn wrote:
Do they have diminished lung capacity and difficulty dealing with the (comparatively) low-oxygen environments of their spaceships and other worlds?
Whatever exotic oxygen transport mechanism the Soia-Liron use would be at least as capable as ours.
My question there didn't have to do with the transport mechanism itself (though I admit, I was responsible for bringing that subject up, for no real reason, because I am dumb), but rather with how they acclimate to local conditions.
A human born and raised at sea level will have more trouble breathing mountain air than a Himalayan native will; I wanted to know if Perrein locals have similar issues when adjusting to, say, Deinar's atmosphere.
I asked because if the Loroi were genetically engineered to grow into a certain template with little deviation, then I would think the Perrein locals might have much less difficulty making the transition from an oxygen-rich to an oxygen-normal or even oxygen-poor atmosphere than a human born in similar conditions would. If their physical capabilities are less influenced by the environment they lived in and more pre-programmed for efficiency's sake than ours are.
As a different example of this line of thinking, say you've got a member of servant race engineered for ground combat on a high-gravity world. You wouldn't want it to develop the weaker muscles and thinner bones you'd expect from a normal-grav world just because he was mass-produced on a normal-grav space station or space ship or planet, right? So if you could, you'd make its body grow those thick bones and strong muscles regardless of upbringing--so there'd be less difference between it and its high-grav-born counterparts than you'd expect if it were from a natural species. (This is assuming that artificial gravity is energy expensive and you wouldn't just crank it up for his species wherever you go--though, looking at Outsider, I would have no reason to make that assumption for this particular setting, since even species just barely getting into interstellar travel like humans have constant gravity on their ships). That sort of thinking, though in a different situation.
Specializing versus standardizing could be a pretty significant advantage in some circumstances and a disadvantage in others, though I'm far too tired to think of a coherent way to explain the good and bad sides of each way. Human tolerance curves shift, Loroi tolerance curves might not--but might be more impressive overall anyways.
It wasn't whether the Loroi would be short of breath compared with humans, but whether Perrein natives have the same sort of difficulty adjusting to lower-oxygen environments that you'd expect from a human.
Sorry for putting that question right after that misleading and inaccurate tangent, that was dumb of me.
And if you understood that and I misread you, I'm doubly sorry, but I still must ask for clarification on the matter as I did not understand your answer.
