In Arthur C. Clarke’s short story “The Other Side of the Sky”, birds didn’t do well in zero-g. In Heinlein’s story “Waldo”, on the other hand, a parakeet (or canary, I can’t recall) had learned to fly like a rocket in zero-g. Of course, it was raised in weightlessness,m so it was used to it. IIRC, a dog in the same story couldn’t cope well with weightlessness.
I’ve always thought that a cat raised in zero-g (as someone suggested above) would have a ball. If the interior of your space environment was covered with carpeting or something where claws could get a god hold, I could see cats leaping gracefully and easily from wall to wall. They’d love it.
But they’d have to grow up with the idea. I know from experience – taking them in the car to the vet – that cats used to normal gravity and inertia don’t respond well to changes.
And, of course, you’d damn well better have a centrifuge with a cat box in it if you want any semblance of sanitary conditions. Or else train your cat to use the vacuum-based Zero Gee toilet from 2001
The flat surface requires gravity, though. The polarization effect @Stranger_On_A_Train is talking about occurs at the water-air interface, and that’s flat only when both are constrained and ordered by gravity.
The obvious way would be pseudo-gravity (e.g., centrifugal force). I don’t know if a sealed box with one flat surface would suffice, but that’s about the only alternative I can think of. Maybe you can suggest something, since you seem to know everything.
Surely the obvious way is just a flat surface on the tank.
I don’t know enough about the physics to know how we might produce a lighted surface that they could use to navigate, but the fact that they do not directly use gravity surely suggests that it might be easier to devise a setup that would work for them in zero-g than a terrestrial animal.
The tank would have to exclude air, or else the water-air interface would be random and irregular.
To accurately simulate planet-bound bodies of water, you would also want to make sure the illumination favors that flat surface since daylight comes from above most daytime hours.
Since the service of animals is involuntary and pretty much fatal in outcome, I’d say the animals best suited for this type of thing are the ones who are blissfully unaware of their impending doom.
I’d be surprised if very many fish species depended on that. There are plenty of sea creatures who live nowhere near the surface. Some have no direct lighting requirements at all. An environment suitable for all the fish in the sea is as unlikely as Noah’s Ark and just as unnecessary for the question here.
Again, the aquatic environment is not “effectively 0-G”; gravity is as present, and has just as much of an effect as on land; even moreso given the dramatic pressure gradient (1 bar/14.7 psi per every 10 meters/32 feet) which many aquatic animals both big and small use. ‘Bony’ fish don’t just use the swim bladder to maintain neutral buoyancy; many also use it to go up or down with minimal effort, and the absence of such a gradient would force them to work much harder.
“Nutrient transport” means that waste products from larger animals drift down to be consumed by benthic microorganisms and scavengers, and plankton back up to the surface, often collecting excess carbon dioxide and other entrained waste products. This occurs even in aquariums (although the filtering and oxygenation is done mechanically the wastes are drawn to the bottom and sides of the tank), and is a crucial feature in any natural marine ecosystem to prevent animals from swimming in and reconsuming their own waste. Could you put a fish in an enclosed tank in freefall and it will figure out a way to swim around? Sure. Will it be healthy and well-adapted to its environment? No.
Octopus, squid, and cuttlefish are common tropes in ‘uplift’ species suitable for space, and the points you make regarding their gripping and manipulative abilities valid. In addition, unlike most marine animals which have a preferred orientation for ‘up’, many cephalopod species are comfortable in any orientation, and because they can actively vector their ‘jet’ are perhaps uniquely suited to freefall conditions. Their eyes are designed to orient using polarization but at much finer gradients than vertebrate eyes, so they would probably be more adaptable to light transmitted through a curved surface. The biggest problem with cephalopods—especially octopus—is their curiosity and ability to escape through any gap. Having an octopus freely floating around in your spacecraft would be unnerving and potentially dangerous as they ‘play’ with any controls or safety-critical systems that they encounter.
It’s expected, and to certain an extent useful to challenge criticism and expand upon why assumptions or misconceptions are not correct. I’ve done a lot of reading about animal physiology in space and freefall conditions but I’m not an expert, and certainly don’t have the last word on the topic. However, the public at large has a lot of misconceptions about living in space that are formed from science fiction literature, movies, and television that just aren’t grounded in fact or observation, and they feed an enthusiast passion for crewed spaceflight and habitation which, while appealing in concept is far more difficult in practice. It is pretty clear that maintaining terrestrial environments for long term habitation in space for humans or animals will require terrestrial-like conditions including a substantial degree of simulated gravity, which may be a show-stopper even for habitats on Mars or Earth’s Moon.
I understand what it means. I just don’t think it’s the obstacle that you claim. Nothing in a spaceship is going to be living in a completely natural ecosystem, and it does not seem like a major engineering challenge to simulate a suitable acquatic environment. The question is what type of animals would likely do best, and there are good reasons to believe that aquatic animals might do better than terrestrial animals in zero-g.
When the fish first attempted to swim in microgravity, they performed weird loops as if they were trying to find their orientation. I have seen an explanation for this somewhere; the fish thought they were falling (which they were), so they swam ‘upwards’ - a behavior which caused them to loop upwards continually.
In due course they found a different way to orient themselves using light levels.
@InternetLegend already suggested tardigrades in post #5. Calling that cheating would be too harsch, but let’s agree that tardigrades are on a league of their own. Now imagine they could reach space on their own, like spiders can reach the jet stream using their silk as a kind of balloon! Panspermia by tardigrade! How did the producers of Dr. Who know how pertinent the name TARDIS would be?
Sorry if my “let’s ignore Stranger” came across the wrong way, I reiterate that your objections are pertinent and true, and I thank you for them. Good to know that those things people daydream about will never come true, you fought a lot of ignorance. And nicely written it is too! It’s just that this thread was not meant to be taken too seriously. I mean, it started with a seal being flown to space by Elon Musk to make up for an experiment conducted on the poor thing to find out whether loud sounds disturb her and her pups. Looked like a good premise to goof around a bit, maybe in the wrong category - perhaps the “Factual” should have been “Mundane”. At least nobody has mentioned yet what the consistency and the odour of seal poop are like. Fishy, I guess.
And nobody has suggested an hippopotamus yet. Poo spraying in space!
If you had a tank of fish in microgravity the water would soon get polluted with excreta, since the solid material would not sink to the bottom of the tank. But perhaps this could be fixed with an efficient filter. On the other hand dolphins would need to breathe air, so you’d need to find some convenient way to get oxygen into their lungs or bloodstream.
David Brin describes water-filled dolphin spacecraft in his Uplift series, but the oxygen problem would not be trivial.
The though of my long-haired cat trying to dislodge a dingleberry while flailing about uncontrollably in zero-g sent me into an equally uncontrollable fit of giggling over both the humor and the horrifying implications of such a scenario.
Aquatic ecosystems are tightly coupled and can experience cascading failures when individual subsystems get out of balance. Anyone who has maintained a large aquarium (especially saltwater) can attest to just how much work it is, and how quickly seemingly small problems can propagate into catastrophic failures if not quickly tended to. I’m sure you could put a fish in an enclosed tank and it would figure out how to swim around with some marginal degree of efficacy; and if you can figure out how to aerate the water it will survive indefinitely, or at least until some infection catches up with it, but I wouldn’t classify that as “doing best”. A viable aquatic or marine ecosystem definitely relies upon gravity in numerous ways despite the perception that neutral buoyancy is ‘similar’ to freefall.
Oh, that’s the way I took it, and I probably am ‘harshing the buzz’ on what is intended as a more casual dorm room bull session, but it’s in my nature to point out false assumptions. In the case of space habitation, I’ve spent enough time and no small amount of more-than-casual interest to understand the problems and have come to the unfortunate knowledge that it is far more complicated than most people (including my younger, less informed self) appreciate.
I’ve swam through sea lion scat while scuba diving, which is best described as ‘soupy’ and incredibly nasty, and will also stick to and stain neoprene and presumably any textile or absorbent material.
Taking a hippopotamus to space would certainly be both an engineering and veterinary challenge, not to mention caretaking and shepherding such a large and dangerous mammal in a confined space. I would call for SpaceX to take on this challenge except that a certain individual would probably take that on as a serious endeavor regardless of the risk and harm to animal and crew.
That’s a straw man. You’re just trying to make the perfect the enemy of the good. Sure, aquatic animals rely upon gravity in their natural state, but the relevant question is could they adapt to life without gravity more easily than terrestrial animals?
You are still arguing against an aquatic Noah’s Ark, not selected aquatic species. Most fish are capable of adjusting their buoyancy and adapting to changes to it required by the changing pressure you pointed out. The water be kept pressurized by more air than can be dissolved in it increasing the oxygen, nitrogen, and CO2 availability to plants and fish and allowing an ideal pressure for the selected species.
Waste products can be consumed by biotic action in the water given enough of water is provided in relation to the volume of fish. That’s how modern salt water aquariums maintain water quality now, though it can be improved with additional filtering. Their health won’t be affected as much as that of any terrestrial animals living in an enclosed space with a growing volume of cat shit floating around.
We are talking about an enclosed aquarium here. It would also have the advantage that the larger biota would automatically fill and holes that open up as anyone who ever had to drain a large aquarium has experienced.
A spacequarium would have the added advantage of a preferrable environment for human inhabitants wearing scuba gear. All movement under water would require additional exertion and the pressure would be maintained at something high enough to require more physical effort to breathe. You’ll find divers to be exceptionally physically fit as a result.
Finally, human inhabitants of such an environment also provide a large emergency supply of water and oxygen given a sufficient power source for filters and hydrolysis, and with the proper species a supply of emergency food. And as proven in another thread seafood would be the preferred type of food to have unless you also have pigs in space and a smoking and curing facility available which would have far greater “nutrient transport” problems.
