Plausible ecology for Hoth?

[Junghalli]

Inspired by discussion in the Rebel Alliance in Star Trek thread.

Hoth, in Star Wars, is supposed to be a frozen iceball. But it has high levels of atmospheric oxygen, which implies photosynthesis, and it somehow manages to support large animals like that big polar bear thing that Luke tangled with. Now I believe the SW EU has some handwaves about lichens growing in caves under the ice, but to be honest that never sounded too convincing to me. So, trying to come up with a semi-plausible ecology for Hoth, here's what I managed.

Hoth is a world a little like our solar system's Europa, in that it has a large ocean of liquid water covered by a thin crust of ice. In many places, due to the temperature hovering just around freezing point or warm upwellings from the deep ocean, the ice crust is very thin, only a few feet or inches thick. In these areas the ice crust is thin enough that sunlight can penetrate it and phytoplankton and other photosynthetic lifeforms can thrive. Along with deep sea thermal vents, these phytoplankton form the base of an extensive oceanic ecosystem.

In places where the ice is thin, there lives a species of terrestrial fish eater. I envision these as bipedal creatures with huge claws, sort of like some Tyrannid forms. They use their giant claws to break holes in the ice and then release into the water some sort of bait that draws the Hoth equivalent of fish toward the surface. When the fish wander by they use their giant claws to skewer them, and this is how they feed.

As for the tauntauns (assuming you dismiss the suggestion that they're just the SW equivalent of sled dogs, and therefore imports, which I personally lean toward), I would suggest that they're probably primarily seaweed eaters. In coastal areas where the ice is thin there may be large beds of kelp-equivalents growing right under the ice, which would provide a ready food source for small numbers of terrestrial herbivores capable of breaking through the ice to get at it.

Together with the fish eaters, the tauntauns could then form a terrestrial food chain capable of supporting small numbers of an apex predator: the wampas (the polar bear type things).

Judging from their size and complexity, I would say it's likely that these creatures are the remnants of a much richer terrestrial ecosystem that probably existed before Hoth endured a runaway glaciation event and entered its present frozen state.

Sound reasonable?

[Darth Yoshi]

My only concern is that if there's sufficient sunlight to power photosynthesis, especially through ice, the planet should be getting enough energy to thaw it out.

[Ziggy Stardust]

What was the name of that one book they made that was all about various Star Wars animal life? I believe that one had a pretty good section on Hoth. The equatorial zone, if I recall, is relatively temperate, in that it supports photosynthesis (mostly through algae, if I recall). This is not an entirely implausible idea.

Hoth is a world a little like our solar system's Europa, in that it has a large ocean of liquid water covered by a thin crust of ice. In many places, due to the temperature hovering just around freezing point or warm upwellings from the deep ocean, the ice crust is very thin, only a few feet or inches thick. In these areas the ice crust is thin enough that sunlight can penetrate it and phytoplankton and other photosynthetic lifeforms can thrive. Along with deep sea thermal vents, these phytoplankton form the base of an extensive oceanic ecosystem.

It can't be that thin: it would be unable to support the extensive underground network the Rebels used as their hidden base. And that the wampas and tauntauns exist in (both survive by living in caves). On that note, however, you could make the argument that the part of the planet the Rebels settled on was rocky and mountainous (I don't recall if we see any rocks or not in ESB), just as parts of Antarctica are. Though, the ice does not need to be thin everywhere for a viable ecosystem to be supported. The cold regions of this planet have enormous biodiversity (and, in fact, are more productive than tropical areas). It is possible for these ecosystems to exist without having to come up with excuses.

In places where the ice is thin, there lives a species of terrestrial fish eater. I envision these as bipedal creatures with huge claws, sort of like some Tyrannid forms. They use their giant claws to break holes in the ice and then release into the water some sort of bait that draws the Hoth equivalent of fish toward the surface. When the fish wander by they use their giant claws to skewer them, and this is how they feed.

Ummmm ... okay, whatever.

As for the tauntauns (assuming you dismiss the suggestion that they're just the SW equivalent of sled dogs, and therefore imports, which I personally lean toward), I would suggest that they're probably primarily seaweed eaters. In coastal areas where the ice is thin there may be large beds of kelp-equivalents growing right under the ice, which would provide a ready food source for small numbers of terrestrial herbivores capable of breaking through the ice to get at it.

How would they get through the ice? There's nothing on a tauntaun that looks like it could be used to break ice, unless it is damned thin. Lichens are just as feasible, if not more so.

My only concern is that if there's sufficient sunlight to power photosynthesis, especially through ice, the planet should be getting enough energy to thaw it out.

Well ... no. Earth has had ice ages, too. By this logic, the tundra should thaw out, because it has a lot of photosynthetic activity during certain parts of the year. When it comes down to it, there is nothing terribly unrealistic about Hoth's ecosystem, although certainly the situation does raise a lot of questions.

[Junghalli]

It can't be that thin: it would be unable to support the extensive underground network the Rebels used as their hidden base. And that the wampas and tauntauns exist in (both survive by living in caves). On that note, however, you could make the argument that the part of the planet the Rebels settled on was rocky and mountainous (I don't recall if we see any rocks or not in ESB), just as parts of Antarctica are.

Well, Hoth could easily have continents, like Earth. The rebel base would logically be on one of the continents.

Ummmm ... okay, whatever.

Such a creature seemed the most reasonable thing I could come up with for the base of a terrestrial food chain.

How would they get through the ice? There's nothing on a tauntaun that looks like it could be used to break ice, unless it is damned thin.

That's true. Although if they feed in areas where the ice is very thin (a few inches), maybe they just whack it open with their tails or horns or noses or something.

Lichens are just as feasible, if not more so.

Would lichens provide enough biomass? It seems an awfully sparse and diffuse source of nourishment for such a large animal. Although maybe something like snow algae could provide sufficient nourishment, if there are really huge areas that are covered by it.

[Darth Yoshi]

Well ... no. Earth has had ice ages, too. By this logic, the tundra should thaw out, because it has a lot of photosynthetic activity during certain parts of the year. When it comes down to it, there is nothing terribly unrealistic about Hoth's ecosystem, although certainly the situation does raise a lot of questions.

Even during the worst of the ice ages, Earth was never totally encased in ice, because there's enough energy to keep the equator thawed. But that's not the case with Hoth, which is supposed to be a frozen all over.

[Junghalli]

Even during the worst of the ice ages, Earth was never totally encased in ice, because there's enough energy to keep the equator thawed. But that's not the case with Hoth, which is supposed to be a frozen all over.

Actually, there is evidence that during periods in the Precambrian the Earth actually was completely frozen over. Snowball Earth. So a planet at around Earth's distance from the sun being completely frozen over is not really implausible.

[Connor MacLeod]

I have a question. Is it neccesary to be totally encased in ice" ALL the time? Maybe there are factors that occur at different points in time that alter the overall climate in areas so its not totally frozen (the distance from the star, for example)

Also, what about the possibility of meteor impacts? IIRC we know Hoth suffered from fairly frrequent impacts (They were concerned about meteor activity making it hard to spot apporaching ships IIRC) perhaps sometimes they get some very large impacts - that could alter temperature/climate changes if they were big enough. Hell even small meteors probably owuld heat up the atmosphere at least some simply by their passage through it)

[JGregory32]

It is not likely that Tauntauns are a species native to hoth. They are too well domisticated for them to be a native speices that the rebels encountered in the few months they have been on Hoth. Domesticating a species to the point where you can ride them to death (like Han did) or not worry about them making a run thorugh the open door takes a large amount of time.

I would also like to point out that both Luke and Han seemed to know how to ride pretty well. Is their any evidence for them having riding skills before Hoth? While it is possible to pick up riding skills in a short peroid of time doing so with feral mounts is next to impossible.

[Batman]

I could swear there was some EU source or other saying a) tauntauns AREN'T native to Hoth, and b) were already domesticated when the Rebels started using them on Hoth, but I can't for the life of me remember which source that was (so I might be just imagining things to begin with).

[FA Xerrik]

I don't know about being pre-domesticated, but the original Essential Guide to Alien Species made a note of tauntauns being especially easy to train if you segregated the genders and won over the matriarch or something. I don't have the book with me, but I can check it tomorrow at earliest. I don't know how plausible that is necessarily, but it seems like an issue that has been given some thought at least in the official material.

[CaptainChewbacca]

In the Star Wars Bestiary (or guide to monsters, or whatever) they do 5 or 8 pages about the ecology of hoth. I'll look for it when I get home.

[Agent Sorchus]

The best evidence of an off Hoth origin for Tauntauns comes from Dark Apprentice where Han takes Kyp Durron skiing there is a brief mention of Tauntauns being ridden. This is only indirect evidence that the rebels imported Tauntauns to Hoth, that Hoth should not be able to supply enough Tauntauns to export within less than a dozen years of any initial Hoth based domestication.

[Wyrm]

If Hoth is indeed a total iceball, then actually the oxygen atmosphere makes sense. See, frozen wastes have this thing called permafrost, where the land is perpetually frozen. Frozen stuff doesn't rot. If most of the carbon on Hoth is locked up in permafrost, and the hydrogen is locked up as water ice, then there's nothing for the oxygen to react with. Therefore, the autotrophic life on Hoth can be comparatively sparse, as there's little oxygen lost to spontaneous oxidation.

Now, the reason why photosynthesis produces oxygen is because light is being used as the source of energy to break up water molecules. It is possible that some autotrophic life on Hoth evolved to use chemical energy rather than light energy for this decomposition step. Therefore, there doesn't have to be much light input for Hoth to maintain an oxygen atmosphere.

So, suppose sometime in the primeval past, Hoth was a normal proto-Earthlike planet, evolving on a path much like Earth, until the Hothian Oxygen Catastrophe. On Earth, there was a sudden changeover from low-oxygen to high-oxygen, and while it cooled the planet, it didn't do so enough to completely freeze it over. Hoth had a different history. Instead of reaching a new equilibrium above global freezing, enough of the biomass was frozen in permafrost to lock its carbon away forever, and you have a runaway iceball effect. The planet gets colder and colder as the carbon dioxide is sucked more and more out of the atmosphere and more and more of the planet is covered by ice (high albedo) until the entire planet is an icy wasteland. Meanwhile, some of the photosynthetic life has evolved to use chemical energy instead. And this leads us to modern day Hoth.

[Johonebesus]

What about the monster? If it's native, then Hoth must have frozen over long after large animals evolved. Assuming it and its relatives breath as we do, they must have evolved long after this "oxygen catastrophe".

Actually Earth may have gone through a similar total glaciation. Supposedly there was a snowball ice age around six or seven hundred million years ago, before animals started to evolve. The runaway glaciation is supposed to have been ended by volcanic activity gradually building up carbon dioxide. Perhaps Hoth's core has cooled and there is no vulcanism.

[Darth Yoshi]

Actually, there is evidence that during periods in the Precambrian the Earth actually was completely frozen over. Snowball Earth. So a planet at around Earth's distance from the sun being completely frozen over is not really implausible.

Huh. I didn't know that. Very well then, conceded.

[starslayer]

Hoth going through a snowball phase seems the most plausible idea to me. There's been enough time for large animals to evolve (the wampa at least), meaning as Johonebesus says, the oxygen catastrophe happened quite a while before the glaciation. The ice would be quite thick, but not so thick as to prevent high mountains from sticking out of the top of the ice, so rock caves are still possible. The seas would still be relatively fertile, though they wouldn't be based on phytoplankton as they are now. Instead, activity would center on the deep sea, mostly around the plate boundaries and vents.

The land ecology is more difficult to determine, because on Earth at the time of the possible snowball phase, no land organisms of any kind were present. It would probably be based around the aforementioned lichens in caves or somesuch, as the herbivores would move from mountain range to mountain range, looking for caves that have some food in them (nothing would survive out on the open glaciers). The wampas would presumably survive on these herbivores, be they tauntauns or something else. Them being so large actually makes sense, because despite the limited quantity of food, being that large makes it easier for them to retain heat due to scaling laws. Thus, they'd require less food for their body weight than something smaller. Like polar bears, they would have enormous territories that they'd range over, given their food requirements.

Perhaps Hoth's core has cooled and there is no vulcanism.

We have no idea when the glaciation started, nor what the plate configuration of Hoth is like. Volcanism of the type that resulted in the end of Snowball Earth may be only just starting, and not in the area of Echo Base. IOW, we simply don't have enough information to say, since we don't know the variability of Hoth's geological activity (Earth's level of activity has varied in the past, IIRC). In any case, all of these processes take hundreds of thousands to millions of years to occur for something on this scale, and we've only seen Hoth over a few thousand years at most (I don't know how much EU material takes place on Hoth).

[Wyrm]

Although the Oxygen Catastrophe theory is pretty well dead, less discovering that multicellular Hoth life such as the wampa are alien imports, permafrost carbon sequestration is still a mechanism for basically taking carbon out of the atmosphere and permanently cooling the planet (provided Hoth remains sub-freezing). We cannot simply ignore its effects, as it would be so widespread. After all, warm-blooded creatures on Hoth have a tendency of freezing to death. There's a reason you don't find crocodiles at the poles. If they are not quickly snatched up by scavengers, the carcasses would simply become another part of the permafrost and their carbon is more or less permanently removed from the biosphere.

Creatures do venture out of the thermal caves (or wherever the energy from the resident autotrophs roam), otherwise the wampas would simply stay put. That means that there are the occasional native creature that migrates. A fraction of these creatures would die during the migration (likely, given that the most probable cause of the migration would be dwindling food supply), and a fraction of the carcasses would never be scavanged.

[open_sketchbook]

So the ecosystem would look something like this then?

Inside deep caves, autotropic life based on chemical reactions in the form of lichen (Perhaps supported by a tiny degree of photosynthesis from filtered light in a nod to the canon expenation) grow, and is eaten by creatures such as the tauntauns. When the amount of lichen grows scarce, these creatures leave the caves and migrate to another cave system, likely following ancestral paths. Along these paths, hibernating Wampas and other predators await these creatures, hunting them as they pass, grabbing as many as possible to ice to the cave roofs as a food supply before returning to hibernation.

[LadyTevar]

So the ecosystem would look something like this then?

Inside deep caves, autotropic life based on chemical reactions in the form of lichen (Perhaps supported by a tiny degree of photosynthesis from filtered light in a nod to the canon expenation) grow, and is eaten by creatures such as the tauntauns. When the amount of lichen grows scarce, these creatures leave the caves and migrate to another cave system, likely following ancestral paths. Along these paths, hibernating Wampas and other predators await these creatures, hunting them as they pass, grabbing as many as possible to ice to the cave roofs as a food supply before returning to hibernation.

I think you may have a good idea there. With the migrations being random, or possibly seasonal depending on how long it takes a cave to recover, food storage and hibernation are good theories for how the Wampas survive. With the Rebels having so many new creatures out running around, the Wampas would 'wake' from hibernation due to the sudden influx of possible food sources, although I forget if more than the one was found near the Base. After the battle of Hoth, any bodies left behind were probably added to some Wampa's storage chamber.

The next question would be if the Wampas live in small family units, or if they roam like Polar bears, where a male's territory overlaps a female's. I see mating only happening in times of Migration when there would be lots of food available for storage, and the cubs staying with the parent(s) for a couple years to learn all the tricks to survive. If migrations are seasonal, that length of nurturing would allow the cub to practice killing and learn proper storage.* I also see the first year or two on their own as the time of greatest mortality, as the immature Wampas spread out to find their own territory.


*This is all based on the idea that Wampas have animal-level intelligence.

[CaptainChewbacca]

OS, your idea is pretty much what the SW ecology book says.

[Havok]

Certainly not an expert, but what about a slow, oblong orbital path that puts it far enough away for a period to freeze over and then a close enough period for it to thaw out?

[open_sketchbook]

Unfortunately that wouldn't really work. Hoth has to have been under ice for a long time for something like the Wampa's cave to form, too long for any plant life to survive until the thaw.

[Junghalli]

Unfortunately that wouldn't really work. Hoth has to have been under ice for a long time for something like the Wampa's cave to form, too long for any plant life to survive until the thaw.

What if the plants leave hardened spores or seeds that stay in suspended animation for decades or centuries and then thaw and rehydrate come the next warm and wet period?

[Elfdart]

I tend to think of the tauntauns as being like reindeer: they might be tame enough to work in brutal arctic conditions, but in the wild, they spend much of their time in relatively warmer regions where there's enough plant life to feed them. They could also be like mustangs in that they might not be "native" to Hoth, but they have lived there long enough to survive in feral herds. Maybe they were imported centuries before as domestic animals (or were domesticated in the warmer regions of Hoth) and have since gone feral as those settlements died off or were abandoned.

[open_sketchbook]

Unfortunately that wouldn't really work. Hoth has to have been under ice for a long time for something like the Wampa's cave to form, too long for any plant life to survive until the thaw.

What if the plants leave hardened spores or seeds that stay in suspended animation for decades or centuries and then thaw and rehydrate come the next warm and wet period?

Hooray for the plants. The animals still starve to death.