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Old 07-04-2010, 06:04 PM   #61
MagiMaster
 
Join Date: Jan 2007
Location: Your imagination
Default Re: GURPS: Ecosystems and Evolution

Someone on a different forum said that a tarantula fed 25% of its body weight once a month would grow, so that's about 1% per day on average. The tables above give about 6.5% per day. (I'm assuming the tarantula weighs 0.15 lbs.) So these numbers don't quite work right, but I don't know which ones need the most work. Does anything look off to anyone else?

Edit: Updated the tables with some better numbers. Tarantulas get about 3% now, which is probably close enough, even though using this would predict about 1/3 the population. I need to look back over things and see what's left. I'm getting some help on another forum for the thermal to watts question. I still need to write up the FP used to hunt question, but I have some ideas there. Is there anything else I need to add?

Edit again: I think the right equation for thermal energy is 1,700,000*(Th - Tc)*(area in mile^2)/(height in ft)*(1-sqrt(Tc/Th)). So the previous example of 200F to 50F would give about 47.5 million watts now (with a 20 ft ceiling), instead of 270 million. I think that's a bit more reasonable. I might need to find some way to simplify that though.

Last edited by MagiMaster; 07-05-2010 at 04:33 AM.
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Old 07-05-2010, 09:56 PM   #62
MagiMaster
 
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Default Re: GURPS: Ecosystems and Evolution

Ok, if there's nothing else missing, I think I have enough to write up an e23 submission. I think I'll leave the worked examples for the submission.

One other question: would anyone be interested in the Evolution section on suggestions for making the life on a planet look like something that could have evolved there instead of something placed there? I'll probably include it anyway, unless I run out of space. I'm just curious how much effort to spend filling it out.

Thanks for all the interest so far. I hope that the finished product lives up to the expectations. :)
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Old 07-08-2010, 10:48 AM   #63
Vaevictis Asmadi
 
Join Date: May 2007
Location: Twin Cities, Minnesota, U.S.A.
Default Re: GURPS: Ecosystems and Evolution

Mostly these numbers look reasonable to me.

Quote:
Originally Posted by MagiMaster View Post
Niche
  • Decomposer - 0.305
  • Scavenger - 0.205
  • Omnivore - 0.205
  • Gathering Herbivore - 1
  • Grazing/Browsing Herbivore - 0.305
  • Pouncing Carnivore - 0.115
  • Chasing Carnivore - 0.45
  • Trapping Carnivore - 0.0675
  • Hijacking Carnivore - 0.205
  • Filter Feeder - 0.027
  • Parasite/Symbiote - 0.0675
Grazing/Browsing Herbivore should be much larger, indeed larger than 1, unless you want to make separate categories for "in an ecosystem where plants/krill/whatever are easy to digest" and "in an ecosystem where plants/krill/whatever are hard to digest."

I am interested in the other section you mentioned, though I can't afford any e23 products until I find a job so maybe I'm not the person to ask. But it does sound like a worthwhile thing to include if there's room.
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I have Confused and Clueless. Sometimes I miss sarcasm and humor, or critically fail my Savoir-Faire roll. None of it is intentional.

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Old 07-08-2010, 04:06 PM   #64
MagiMaster
 
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Default Re: GURPS: Ecosystems and Evolution

Yeah, that makes sense. Would 1.2 be about right? (I should look up some details for some RL grazers and see what that'd suggest.)

Edit: Hmm... I found some info on whitetailed deer that suggest they eat about 3% of their body weight per day. For a 200 lbs deer, that'd give a factor of 0.09. My current numbers give 0.18. If I raised grazers to 1.2, it go up to 0.71. Either grazing is roughly right (grazers may eat low energy food, but they don't spend much energy getting it) or some of my other numbers are really far off.

(I should point out that I'm probably going to just accept an error of a factor of 2. I don't think such a simple formula can really do better than that.)

Last edited by MagiMaster; 07-08-2010 at 04:26 PM.
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Old 07-09-2010, 09:11 AM   #65
Vaevictis Asmadi
 
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Default Re: GURPS: Ecosystems and Evolution

I don't think you can combine browsers and grazers together. In fact, I don't know that you can combine ruminants and non-ruminants together. Cows, hippos, and elephants eat different proportions of their body weights each day, for example. It depends on how generic you want to be, but I would at least separate browsers and grazers, or better yet provide a "high-efficiency browser/grazer" and a "low-efficiency browser/grazer" so that the categories aren't Earth-specific.
__________________
I have Confused and Clueless. Sometimes I miss sarcasm and humor, or critically fail my Savoir-Faire roll. None of it is intentional.

Published GURPS Settings
(as of 4/2013 -- I hope to update it someday...)
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Old 07-09-2010, 05:46 PM   #66
MagiMaster
 
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Default Re: GURPS: Ecosystems and Evolution

I'm trying to stick to the categories in GURPS Space, which combines grazing and browsing. BTW, what would a high-efficiency grazer be? That sounds a lot like a gathering herbivore. Also, the day-to-day intake is below the resolution of this. All I care about is long-term averages.

Anyway, like I said, the current numbers predict the value for a whitetailed deer pretty well, so either the numbers I have for grazers is about right, or everything is off in a way that balances out for that one example.

I should mention the examples I've got so far, just to make sure I'm not doing something wrong with them:
- Anaconda, 215 lbs, eats about 0.3% body weight daily, Pouncing carnivore, Slithering, Cold-blooded (w/ dis), Scales, Egg-laying, Medium r strategy, Preprogrammed, No bond, Solitary
- Hummingbird, 0.0044 lbs, eats about 500% daily, Gathering herbivore, Winged flight, Warm-blooded, Feathers, Egg-laying, Medium K strategy, Low intelligence, Temporary bond, Pair-bonded society
- Tarantula, 0.15 lbs, 1% daily, Pouncing carnivore, Walking, Cold-blooded (w/o dis), Tough exoskeleton, Egg-laying, Strong r strategy, Preprogrammed, No bond, Solitary
- Deer, 200 lbs, 3% daily, Grazing herbivore, Walking, Warm-blooded, Fur, Live birth, Medium K strategy, Low intelligence, No bond, Small group
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Old 07-09-2010, 09:57 PM   #67
Vaevictis Asmadi
 
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Default Re: GURPS: Ecosystems and Evolution

Well elephants are much less efficient than ruminants, of which the cows are significantly less efficient than hippos. And AFAIK grass is more difficult to digest than broadleaf plants, so I'm surprised that the writers collapsed grazers into browsers.

In Uplift, (assuming the Space system is based on the Uplift version from 3E) herbivores are divided into grazers (low-energy food, time-intensive), browsers (mid-energy food, less time-intensive), saprophytes (very low-energy food and time-intensive), and gatherers (high-energy food). Maybe saprophytes correspond to 4E decomposers?

Baleen whales and anteaters are listed under both grazers and gatherers, clearly a mistake. Krill and insects are meat, so gathering seems a more appropriate category. Perhaps they became the 4E filter-feeder category.

The other Uplift diet categories are pouncer (incl. trapper), stalker, chaser, herder, carrion scavenger, gatherer/hunter, opportunist browser, hunter/browser, pure ergivore, mixed ergivore, plant, and tapper.

Out of curiosity, what are hijacking carnivores?
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I have Confused and Clueless. Sometimes I miss sarcasm and humor, or critically fail my Savoir-Faire roll. None of it is intentional.

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(as of 4/2013 -- I hope to update it someday...)
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Old 07-10-2010, 02:57 AM   #68
Haseri
 
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Default Re: GURPS: Ecosystems and Evolution

Quote:
Originally Posted by Vaevictis Asmadi View Post
Out of curiosity, what are hijacking carnivores?
They are big carnivores that can just scare off other predators from thier own kill. Of course, they have the ability to hunt themselves.
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Old 07-10-2010, 03:38 AM   #69
MagiMaster
 
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Default Re: GURPS: Ecosystems and Evolution

Space describes both grazers and browsers as consumers of lots of low energy food, with grazers as eating grass and browsers as eating leaves. Filter-feeders are described as generally sessile. I'd probably call a baleen whale a trapping carnivore, and I'm not too sure about an anteater, but they're probably closer to trappers than anything else.

Hijacking carnivores are described as fierce chasing or pouncing carnivores that get at least a portion of their diet by taking it from other carnivores. Lions might qualify.

Wiki has stats on elephants, so I can add them to my list of test points. My system predicts that a 20000 lbs elephant would eat about 1.8% per day, and the actual numbers come out to about 3% per day. That's within my factor of 2 margin of error. It seems like my numbers may not be too far off.

Anyway, just in case I made a mistake, here are the stats I'm using for an elephant:
- 20000 lbs, 3% per day, Grazing/browsing herbivore, Walking, Warm-blooded, Thick hide, Live-bearing, Strong K strategy, Presapient, Temporary bond, Medium group
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Old 07-24-2010, 04:50 PM   #70
MagiMaster
 
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Default Re: GURPS: Ecosystems and Evolution

Dang. I keep forgetting to write up my thoughts on FP used to hunt. I'm not sure whether or not I'll include it in the final version, but I did have some thoughts:
  • Most animals would avoid going below 1/3 FP, since that'd put them in danger from other predators. They'd only burn past that if they were being chased by something already, or otherwise in mortal danger. Let's say most animals will avoid spending more than 1/2 FP at once. Since Basic gives every animal between 10 and 13 HT, they'd have 5 or 6 FP to spend on a hunt.
  • It's below the resolution of GURPS, but increasing average FP expenditure should increase consumption. I'm going to make a wild guess that an average creature can expend up to its maximum FP in total per day without losing weight/increasing consumption.
  • Pouncing carnivores probably spend this FP one or two at a time for extra effort.
  • Chasing carnivores probably spend between 2 and 6 FP sprinting in a few chases per day. (Cheetahs: "Only half of the chases, which last from 20-60 seconds, are successful.")
  • Trapping carnivores probably spend the FP building the traps. For creatures as small as spiders, it'd be reasonable to assume that making the webs costs FP, though only slowly. Trapping carnivores probably don't use up as much FP as most other carnivores.
  • Hijackers spend FP as per their primary hunting technique, plus one or two for sprinting or extra effort when stealing a kill.
  • Scavengers spend FP to sprint in, extra effort some food away, then sprint out (hyenas), or they spend FP hiking to food saving a bit to sprint away from trouble (vultures).
  • Grazing/browsing herbivores spend some FP hiking and some for defences. They eat very low quality food, but spend very little effort to collect it (lots and lots of it.)
  • Gathering herbivores spend some on extra effort to reach juicy bits of food, and some on defences.
  • Decomposers (the moving kind) spend some on hiking or sprinting to get to their next meal, but then save everything else for defences.
  • Omnivores do pretty much all of the above depending on the exact animal.
  • Filter-feeders, autotrophs, sessile decomposers, parasites and symbiotes don't spend FP except on special defences, or hiking or sprinting while in a mobile form (larva or whatever).
  • Of course, any animal might spend some FP on other things. These are just what I think the main expenditures would be.

Did I miss anything? Do you think this info would be useful to a worldbuilder using the rest of the system?
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