Random Worldbuilding Questions (Biology, Geography, Society, etc.)

[Beleriphon]

Can you travel upriver on a sailship if winds are not completely in your favor? The geography would be somewhat like the United States eastcost (though without the Appalachians causing the land to rise quickly) or the Chinese coast, with rivers generally flowing from Northwest-West to Southeast-East. I think in those longitudes, winds would be mostly Southwest to Northeast, which isn't exactly pushing any ships against the current.
Could you still use sailships, or would you have to switch to rowboats?

Generally speaking you can't easily sail up most rivers without some kind of outside power source. That can be dragging barges via beasts of burden, wind or oars. If the winds aren't favourable you'd be looking at rowers propelling the boat up the river.

[Yora]

I think having different types of crafts for sea travel and river travel would probably the best way to handle it. Which means having trading posts at the mouth of every major river where goods are reloaded. Since it would be different crews and they don't want to make the return trip with an empty hold, there would be lots of trading going on in those places, making them attractive for nearby locals as well.
Lots of opportunity to flesh out a setting.

[Raum]

That would strongly indicate that merchant companies in my setting are mostly opperating by boat. That certainly adds an interesting new element to it.

Can you travel upriver on a sailship if winds are not completely in your favor?

If the river is large enough, yes. (I've sailed on rivers - granted, it was a 28' boat not a cargo barge. ) Other methods include poling, water wheels, or using your mules on land to pull the boat. Each has been used at one point or another in history.

The geography would be somewhat like the United States eastcost (though without the Appalachians causing the land to rise quickly) or the Chinese coast, with rivers generally flowing from Northwest-West to Southeast-East. I think in those longitudes, winds would be mostly Southwest to Northeast, which isn't exactly pushing any ships against the current.
Could you still use sailships, or would you have to switch to rowboats?

You can still sail, it will just limit the size of the ship compared to the river. Sailing upwind means you need to tack. That said, relatively flat coastal areas probably mean slow rivers so poling upriver is a good option.

When you're looking at the size of your craft, do remember you'll need to portage them past serious rapids and any falls. Of course you could also put trading cities at those points and simply sell / transfer the goods to another craft on the other side of the obstacle.

I think having different types of crafts for sea travel and river travel would probably the best way to handle it.

Yes, you'll almost always have different types of craft for sea vs river. If nothing else, you typically need a relatively shallow draft craft in the river to navigate shallow water and deeper draft craft in the ocean to make them more seaworthy. A river craft in an ocean storm is a recipe for a disaster movie.

[Vortalism]

I have two questions really, if that's ok with everyone. Also you'll notice that these questions are sorta newbie, I'm fairly new to world-building as I've always been more of a player, now turned GM.

Biology/Ecology: Question A
In a world supposedly populated by tons of high functioning predators (Monster Manual) how would they support themselves off of the relatively light additions the MM makes to prey animals and herbivores? With so much competition it would be expected that there would be at least twice as many permutations of prey to avoid said predators and their "supernatural" abilities. How do I make sense of this without adding tons and tons of magical prey animals?

Roman Economics: Question B
So my campaign world is set in a pseudo-Greco-Roman Empire with technological levels of the Late Middle Ages (think late 1300s-1400s), and since I don't know how to put this in any elegant way whatsoever... how do I "not-break" the economy with Wizards that could potentially transmute all the iron needed for raw materials ever? I just need help justifying how high functioning magic exists without the a huge percentage of value being lost in just about everything.

[Yora]

I think with predators and prey, every situation will eventually find a point where the numbers are steady so the predators can sustain their numbers without causing the prey population to drop anymore. In practice you frequently have regular fluctuations, but in the end the "high predator" periods and "high prey" periods should level out in the long run.
When it comes to adding more species to a made-up ecosystem, you are not really adding more predators, but you're simply making the range of predator species more diverse. Instead of 10,000 wolves, you then have 4,000 wolves, 2,000 worgs, and 1,000 dire wolves, who eat just the same amount of prey.

As long as the same amount of prey is consumed by the predators, it doesn't really make much difference how many different species the predators are.

Regarding magic economy: Simply limit the amount of spellcasters who can do certain things in relation to the amount of work that has to be done. If you need 10,000 units of something and the wizards can make only create 500, you still need normal means to get the other 9,500. And of course, the wizards will want to sell their creation at just a tiny bit lower than the market price for common goods. Just because they have lover production costs doesn't mean they will sell it cheap.
Also, they have better things to do than making things that can just be done equally well by manual labor. They will want to do things that can only be done with their magic.

[Beleriphon]

Roman Economics: Question B
So my campaign world is set in a pseudo-Greco-Roman Empire with technological levels of the Late Middle Ages (think late 1300s-1400s), and since I don't know how to put this in any elegant way whatsoever... how do I "not-break" the economy with Wizards that could potentially transmute all the iron needed for raw materials ever? I just need help justifying how high functioning magic exists without the a huge percentage of value being lost in just about everything.

For the same reason a person with a doctorate in some engineering field doesn't work in a factory pulling plastic bits out of a machine: It isn't worth their time.

[fusilier]

Yes, you'll almost always have different types of craft for sea vs river. If nothing else, you typically need a relatively shallow draft craft in the river to navigate shallow water and deeper draft craft in the ocean to make them more seaworthy. A river craft in an ocean storm is a recipe for a disaster movie.

Historically, some ocean going ships have been able to penetrate fairly deep into large rivers. It depends upon the ship and the river.

[Raum]

Historically, some ocean going ships have been able to penetrate fairly deep into large rivers. It depends upon the ship and the river.

Of course, there are too many variations in both river size and ship design to think anything else.

[Gnoman]

Roman Economics: Question B
So my campaign world is set in a pseudo-Greco-Roman Empire with technological levels of the Late Middle Ages (think late 1300s-1400s), and since I don't know how to put this in any elegant way whatsoever... how do I "not-break" the economy with Wizards that could potentially transmute all the iron needed for raw materials ever? I just need help justifying how high functioning magic exists without the a huge percentage of value being lost in just about everything.

Simple. Just rewrite the laws of magic slightly to include a Law of Equivalent Exchange or similar, so that, for example, the DnD 3.5 spell Wall of Iron sucks iron out of the earth (or, potentially worse, the surrounding area) instead of creating it (or sucking it out of an elemental plane or whatever). This will be too minor to affect players, but make magic a limited choice on a large scale.

[Yora]

It would still be a very neat way of iron extraction. Much more efficient than digging the ore from hard rock and processing it in a labor and energy consuming process. With mages available for regular work in the mines being probably rare, that method would probably be used in areas where digging through the rock would be especially difficult and slow. Where digging is easier, hiring a mage to suck the iron from the surrounding rocks would probably be too expensive.
Getting a hired wizard to cast wall of iron costs over 6,000 sp. You can pay 2,000 miners and smelters per day with that money. Or 65 of them for a whole month. Not sure how much iron you get from ore, but 65 people working for a whole month every day should produce a quite considerable amount.

[Tirunedeth]

It would still be a very neat way of iron extraction. Much more efficient than digging the ore from hard rock and processing it in a labor and energy consuming process. With mages available for regular work in the mines being probably rare, that method would probably be used in areas where digging through the rock would be especially difficult and slow. Where digging is easier, hiring a mage to suck the iron from the surrounding rocks would probably be too expensive.
Getting a hired wizard to cast wall of iron costs over 6,000 sp. You can pay 2,000 miners and smelters per day with that money. Or 65 of them for a whole month. Not sure how much iron you get from ore, but 65 people working for a whole month every day should produce a quite considerable amount.

According to the SRD, a Wall of Iron has an area of 5 square feet per caster level and a thickness of 1 inch per four caster levels. At the minimum caster level of 11, this equates to some 12.6 cubic feet of iron, or 0.357 cubic meters. Given iron's density, this works out to some 6,200 lbs of iron. While I don't know how much iron 65 people could mine in a month, I do know that the SRD puts the cost of a pound of iron at 1 sp. So, the D&D economy is somewhat consistent in at least this regard, although I should probably note that the amount of iron conjured goes up quadratically while the cost to get someone to cast a spell is linear, so it becomes more economical the higher the spellcaster's level is.

Edit: Well, I forgot to multiply by five in there when figuring the volume, so I'm actually off by a factor of five, and even at minimum caster level Wall of Iron is vastly cheaper than buying iron. So, yeah, never mind.

[Beleriphon]

Getting a hired wizard to cast wall of iron costs over 6,000 sp. You can pay 2,000 miners and smelters per day with that money. Or 65 of them for a whole month. Not sure how much iron you get from ore, but 65 people working for a whole month every day should produce a quite considerable amount.

65 people isn't that many when you're working a mine. Even a modern mine using high explosives employs hundreds, if not thousands of people working twenty-four hours a day. Ancient Roman mines were almost universally manned by slaves, so you don't need to worry about pay. I'd wager to run a fully operational mine you'd need at least 300 workers, just to keep three shifts constantly pulling ore out of the ground. This isn't taking into account the need to at least smelt the metal out of the raw ore to get a remotely usable form.

[Vahir]

Question: Is it possible for self sufficient underground societies (Such as, say, dwarves) to exist? More specifically, can edible crops realistically be farmed underground? Also, would living forever underground be possible from a health perspective?

Other question: How do trade hubs become so wealthy? Let's say City A produces something which is needed in City C, but all the traders have to pass through City B. Selling supplies to traders doesn't seem lucrative enough to justify such prosperity in City B.

[Jacob.Tyr]

Question: Is it possible for self sufficient underground societies (Such as, say, dwarves) to exist? More specifically, can edible crops realistically be farmed underground? Also, would living forever underground be possible from a health perspective?

Lots of animals spend their entire lives underground, so it's more than possible from a health perspective. Dwarves would just have different physiologies/diets to make up for production of things other races might be using the sun to do.

As far as farming goes... leaf-cutter ants might be a natural example? Oyster mushrooms grow on cellulose, so they can be mass produced using wood pulp as a base. I guess if your dwarves are willing to drag some dead trees underground they could farm fungi pretty easily.
More than likely, though, I'd assume they would live off of some sort of underground river with cave fish.
Alternatively if they're in a particularly volcanic region there might be sulfur based life that forms around vents and doesn't require sunlight.

So no farming other than fungus, and that would probably require input from above ground. But fish/crustaceans in underground lakes/rivers is a possibility. Converting your subterranean fish into fungus doesn't seem worthwhile, though.

I always just assumed dwarves imported most everything, having long ago realized they could "make" more food by just purchasing it with what they can mine.

Other question: How do trade hubs become so wealthy? Let's say City A produces something which is needed in City C, but all the traders have to pass through City B. Selling supplies to traders doesn't seem lucrative enough to justify such prosperity in City B.

For your second question: Presumably if City A is sending the needed goods to City C, City C is sending something back in return. City B might be a good halfway point, where traders from both cities exchange goods with each other and head back home. City B probably takes a cut of goods entering the city, or a fee per caravan wagon load, and in exchange offers protection. A safe place to sell valuables is worth a decent bit, and when access to that place allows you to sell those goods after only traveling half the distance it is more than worth a little bit off the top.

[Aux-Ash]

On wall of Iron as opposed to mines:
Remember that the wall of iron can't just be molten down like that. You need to take it apart and melt it down piece by piece as well. Just because you can summon it does not mean you do not need a massive workforce to turn the wall into objects.
And need I say that sawing and hacking off chunks out of a thick sheet of iron with no modern tools is not at all easy. The mine might very well be much quicker.

Futhermore, if the WoI is pure iron, then it may be unsuitable for making tools, armour and weapons since it'd be much too brittle for any prolonged or high-stress use.

Question: Is it possible for self sufficient underground societies (Such as, say, dwarves) to exist? More specifically, can edible crops realistically be farmed underground? Also, would living forever underground be possible from a health perspective?

Based on our world? Doubtful. There's plenty of organisms that do not need sunlight, and some are even funghi. But it would not be a very rich diet. Maybe you can find the odd fish as well, but they're hardly very big.

And if dwarves are anything like humans at all, they need the Vitamin D that we get mostly from exposure to sunlight. A lack of that is going to lead to depression, lethargy, scurvy and other forms of malnutrition.

Personally, I'd have the dwarves build underground fortresses in the mountains and then have surface dwarves in hidden valley and such tasked with growing and breeding the food for the fortress.

Other question: How do trade hubs become so wealthy? Let's say City A produces something which is needed in City C, but all the traders have to pass through City B. Selling supplies to traders doesn't seem lucrative enough to justify such prosperity in City B.

Short answer: The same way anyone does, by buying cheap and selling with a profit.

To elaborate: No farmer can afford to take his crop halfway around the world, no matter how much it is worth. So he sells it at the market at the local town. There the smallscale merchants rent space on riverbarges or with caravaneers. These transports haul the goods to the first trade hub, where the large merchant houses buy the goods at a price both parties are satisfied (-ish) with.
Said merchant houses then pack the crates on ships (or another caravan) and haul it over to the next centre of trade where they do the same thing. These journeys are expensive and risky so they don't want to pay for too long ones. Plus, shorter trips means you can afford to do it more often.

And so the goods travel from one trade hub to the next. Every time the merchants involved takes off a piece for themselves, tolls are paid and the price increases. Couple with that some of it is continously sold off for consumtion, bandits and thieves stealing part of the cargo and so forth.

So every leg along the journey the price increases and the difference stays in that trade hub. That's why trade hubs become so rich. They do not sell goods as much as facilitate the trade, and they charge a reasonable sum for it.

And, to finish up with your example, if City A and City C are so close to one another that there's no point in selling in City B... then City B is not a centre of trade.

[hymer]

Aux-Ash is spot on.
It's also worth noting that trade attracts trade. Once a trade hub becomes the centre of commerce for the region, once you get your hands on a shipment of X, where better to find a buyer quick? And because everyone knows that this is where the merchants go, so do people in search of specific things. Which makes even more merchants go, etc.
The only place you are likely to find a better bargain is where they produce the stuff. So if the mines are east of the trade hub, the marble quarries to the west, the great forest to the north and the expansive wheat fields to the south, you can either journey in a great circle to get the goods from these regions, or you can go to the hub and pick everything up at once. It may be more expensive there, but you can arrange to get your stuff in a few days instead of a few months.
Trade is also what builds cities. Add 100 new merchants and their dependents to a city, and the local landowners have more people to sell agricultural products to, the local carpenters get more work making buildings, furniture and such, the seamstresses get another batch of bodies to cover up. As demand rises, supply scrambles to follow, which means more people to work the land, make lumber for the carpenters and make cloth for the seamstresses. So demand rises again.

[Tirunedeth]

Edit: Well, I forgot to multiply by five in there when figuring the volume, so I'm actually off by a factor of five, and even at minimum caster level Wall of Iron is vastly cheaper than buying iron. So, yeah, never mind.

And it turns out there are more errors, including forgetting to divide by twelve when I was checking my work. So, for the sake of setting the record straight, I've redone all my math:

Caster level: L
Area of wall: A = (25 ft²)*L <- This is where I made one mistake: a five-foot square is 25 square feet, not 5 square feet. I really should know better...
Thickness of wall: t = (0.25 in)*L = (0.0208 ft)*L
Volume of wall: V = A*t = (25 ft² * 0.0208 ft)*L² = (0.52 ft³)*L²
3.2808 ft = 100 cm => 35.3 ft³ = 10⁶ cm³
Volume (in metric): V = (0.52 ft³ * 10⁶ cm³ / 35.3 ft³)*L² = (14,700 cm³)*L²
Density of iron: D = 7.874 g/cm³
1000 g = 2.205 lbs
Density of iron: D = 7.874 g/cm³ * 2.205 lbs / 1000 g = 0.0174 lbs/cm³
Mass of wall: M = D*V = (0.0174 lbs/cm³ * 14,700 cm³)*L² = (256 lbs)*L²

Minimum caster level for Wall of Iron: L_min = 11
Then, mass of wall at minimum caster level is:
M_min = (256 lbs)*L²_min = (256 lbs)*(11)² = 31,000 lbs

To reiterate the price from the SRD, 1 lb of iron is worth 1 sp. The cost to have someone cast a 6th-level spell is 60 gp per caster level plus the cost of any material components (which is 50 gp worth of gold dust for Wall of Iron). That equates to 7,100 sp for an 11th level caster. Of course, as Aux-Ash notes, there are all kinds of costs associated with processing the Wall of Iron into usable form. Whether that would make up the difference is another question.

[Stray]

Other question: How do trade hubs become so wealthy? Let's say City A produces something which is needed in City C, but all the traders have to pass through City B. Selling supplies to traders doesn't seem lucrative enough to justify such prosperity in City B.

Some cities in mediaeval Europe had something called Staple right or Storage right - merchants passing through were obliged to offer their goods for sale on the local market. This could range from "display your wares for set amount of time and then you can leave with the rest" or "sell a fraction of your goods and you can move on" to extreme example of "you have to sell all your cargo here". This kind of privilege was granted and enforced by a king or other lawgiver in the region. Avoiding it would turn merchants into outlaws, and it's hard to run from justice with wagons full of goods. Seems nasty from modern free trade point of view, but those were different times.

[fusilier]

Some cities in mediaeval Europe had something called Staple right or Storage right - merchants passing through were obliged to offer their goods for sale on the local market. This could range from "display your wares for set amount of time and then you can leave with the rest" or "sell a fraction of your goods and you can move on" to extreme example of "you have to sell all your cargo here". This kind of privilege was granted and enforced by a king or other lawgiver in the region. Avoiding it would turn merchants into outlaws, and it's hard to run from justice with wagons full of goods. Seems nasty from modern free trade point of view, but those were different times.

They also just straight out taxed them.

However, if a lot of trade is passing through a particular city then it will become a logical point for merchants (especially middle men) to set up business. It would make it easier to coordinate different trading enterprises, and would be a logical base for freight carriers.

[Yora]

Are there any animals that actually impale their prey on their horns or use them to stab attackers?
All honed animals I know of actually just headbut each other with their skulls, but don't stab at each others with the horns.

[hymer]

For actual horns (not tusks or the sort of protuberance a rhino sports), the main function is arguably cooling down. Blood passes through the horns in order to cool down (and do what blood does in general).
That said, bull fighters have been known to get impaled on a bull's horns. When you use your horns for dominance fights, they shouldn't really impale too easily, or you'll kill rather than subjugate your rival - bad for the species overall to have young males killed off by the older ones. So a bull's horns are more likely to impale someone trying to avoid getting trampled than someone who puts his forehead to the bull's forehead. If they're not a bull themelves, though, odds are they won't be trying something so foolish.

[TheStranger]

Well, I've heard of people getting gored by bulls.

I think the thing to look at is the shape of the horns (or antlers). Blunt, curving horns = headbutting. Pointy, forward-facing horns = goring. That's probably a gross oversimplification, but my thinking is that any animal with horns of the right configuration can and will use them to cause injury, even if that's not its primary attack.

[Spiryt]

There are countless gorish videos and pictures of people being impaled by bulls horns. Mostly during many different Spanish festivals, of course.

[Roguenewb]

Question: Is it possible for self sufficient underground societies (Such as, say, dwarves) to exist? More specifically, can edible crops realistically be farmed underground? Also, would living forever underground be possible from a health perspective?

Question 1: Short Answer: No. Long Answer: Not really, but maybe somewhere that isn't Earth. There are complications like Vitamin D and such, but there are biosynthetic pathways that bypass the need for high energy photon input, and would theorectially be evolved in dwarves/drow/whatever; the real problem is thermodynamics. All the cave systems on earth eventually get their energy from the sun, if you backtrack. Leafcutter ants bring in plants from the surface, water carries in bacteria and debris and bats eat outside then die inside, so on and so forth.

: Every living thing requires X amount of energy every day to maintain its internal environment, a condition essential for life. A portion of this energy (X/Y) is released as low density heat and is essentially useless for all future interactions (If you are familiar with the concept of Entropy, this is it, right here) as it lacks sufficient order to be exploited. If you consider energy released as heat to be lost, which it essentially is, it becomes very clear that a source of energy is needed. On Earth, almost (not quite, but very, very, veryx99 close) all this energy is provided by electromagnetic radiation from the sun (light). The light has a high degree of order, as well as energy, and can be fed into various systems to tie up the energy for later use. On Earth, plants use the light to invest in creating energetic chemical bonds found in glucose (eventually, photosynthesis is a multistage process). Some of the light energy is moved into those bonds, some is lost as heat, and some bounces off as green light.

In the underground environment, you can, with diligence, set up a nearly perfect cycle of nutrients, minerals and vitamins. This doesn't include energy however. Every second, those creatures are radiating energy that entered the underground as glucose bonds, and is being lost forever. Because of the fundamental principles of entropy, its not even possible to recover that radiated heat in a meaningful way, some will always be lost.

But, as Fantasy and Science Fiction Writer (which all DMs are to an extent) you have a cool situation to be in. Undersea vents have demonstrated that there are multiple ways to make glucose (they steal the energy from high energy sulfur bonds and move it into those glucose bonds), and you can write a new one! Maybe, deep beneath the earth, the energy of the Magma God Voristtha leaks off his prison, and a strange red leafed plant called God's Leaf grows off that energy instead of sunlight. God's Leaf provides a basis for all food webs. Supports fungi, insects, mammals and so on, just like grass and trees.

Or maybe an archmage cast the epic spell "Enthalpic Mastery" a million years ago on this cave, and zero energy is ever lost on reactions underground. Spellcraft DC 12934 because it is the best transmutation ever. Plus, for underground farms, Wizards could just create magic light sources. In this case, the energy flow of arcane magic from wherever/divine power from the gods, replaces the flow in of fresh light energy that normal ecosystems need.

Maybe as the souls of the dead pass downwards into hell from the world above, some of their energy is leeched by Ghost Grass, a strange glowing fungus type growth that covers many walls in the Underdark. Maybe arcane energy from spells cast above drifts downward from above, and provides energy like drifting animal debris feeds the bottom of the deep oceans.

All of this is possible answers, but, you need an energy source for the community. Closed cycles are definitionally impossible. Even life on Earth isn't a closed eternal cycle, it just lasts 10 billion years so we can't really concieve of it ending. Have fun writing your answer!

PS

Spoiler

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Fungi isn't a plant. It grows on dying, decompising things. The classic undergound glowing mushrooms are b*******. They don't make fresh sugar, they eat the world around them. I know its classic enough to forgive, but technically, its wrong.

Second Question: Yes. There are immortal living things on Earth right now. Some trees to name just one. There are some animals as well that theoretically don't have senescence in the way we experience it. Death is, to an extent, preprogrammed in our genes, because it creates room for the next generation and makes evolution easier. You die so your kids can replace you, harsh.

Immortality is difficult for us right now because our cells have these timers called telomeres that wear out and do cell damage as they get too short. Accumulated cell damage, from this process as well as damage from DNA affecting exposure to light and chemicals builds up and our systems get weaker, and something eventually kills us (note, age doesn't generally actually kill us, if nothing else, cancer will eventually get you from all this DNA damage). Since our cells lengthen these telomeres/timers every time a fresh egg is made, and you consider a mother->child->grandchild succession a single organism (which cellularly it is in a lot of ways), we are currently making up part of a 3.4 billion year old living thing. Not to get Gaia-ish on here (CURSE YOU LOVELOCK), we aren't really a single being, but in terms of overcoming cellular aging and death, we are.

You can easily have a species that replaces its telomeres every division, and is functionally immortal (from aging). I believe there are reports that some fish on earth are like this, but I don't wanna stretch my google fu to prove it.

[Geostationary]

Fungi isn't a plant. It grows on dying, decompising things. The classic undergound glowing mushrooms are b*******. They don't make fresh sugar, they eat the world around them. I know its classic enough to forgive, but technically, its wrong.

Fungi are also vitally important plant and algal symbiotes, so less wrong than you think. If you're making up an underground ecosystem, lichenesque symbioses could be a great way to add energy to the system using archaebacteria that can subsist off of chemosynthesis.

You can easily have a species that replaces its telomeres every division, and is functionally immortal (from aging). I believe there are reports that some fish on earth are like this, but I don't wanna stretch my google fu to prove it.

One way to avoid the end replication problem is to just not have ends in the first place, or to have methods by which it becomes a non-issue. For example, anything with a circular genome doesn't have to worry about this as it has no ends to shorten.

And I believe you're thinking of certain jellyfish species. Fish don't do anything like that to my knowledge.

[Jacob.Tyr]

On the living underground permanently idea: There's another way it might be plausible to continuously grow fungi. It, again, requires an input.

****.

Literally, ****. Maybe the "farm" rests under a rather permeable area of rock beneath a rookery or other place large numbers of animals flock. If sufficient nutrients trickle in via permeable rock you might be able to establish fungal agriculture based on it (mycoculture?).

Alternatively **** could come in via your world's equivalent of bats. Bat guano can create a large nutrient source in caves, as thousands of bats enter during the day and release feces to the ground.

[Gahrer]

You can easily have a species that replaces its telomeres every division, and is functionally immortal (from aging).

That would not be enough, I think, for a multi-celled organism. As Roguenewb pointed out external factors will slowly but steadily damage the DNA in the organisms cells which will cause some of them to "misbehave" in one way or another - for example by dividing uncontrollably (cancer) or simply malfunction. A truly immortal, multi-celled organism would need to find a way to counter this damage far more efficently than we humans do and to more efficiently deal with and replace large sections of the body as the start to deteriorate from external wear and tear.

Single-celled organisms doesn't suffer as much from these problems. If one bacteria in a group starts to "malfunction" the rest of them can keep on going without much trouble. Also, it is really difficult to define lifespans for bacteria since they divide and create two "new" individuals without leaving an "old" one behind. In practice a given bacteria are immortal since all it's "offspring" can be considered to be the same organism in some manner.

(For an example of immortal human (more or less) cells, check out the HeLa cell line.)

[Zahhak]

I'm sure this has been brought up before, but does anyone have any resources on things like basic strategies to counter predators (ie, not being seen, being faster than the predator, being bigger and meaner than predators, etc), basic predator strategies, and info on how animals form and fill biological niches? You know, all of the basic stuff you would need if you were trying to build a functional flora and fauna for a place.

[awa]

thing is there is no standard set of things all ecosystems have. Deep sea vents share very few similarities with say a jungle.

[Eric Tolle]

Well in D&D land, the solution for your Dwarven city is simple: have someone cast "Stone to Flesh" on the cavern wall. One casting can provide approximately 4,500 pounds of flesh, which can then be eaten or used as a good source for fungi. So the answer is literally, "A wizard did it."