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Thread: Consumption per body weight

  1. #1 Consumption per body weight 
    Forum Radioactive Isotope MagiMaster's Avatar
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    Does anyone here know where I can find numbers for the percentage of body weight consumed per day for a variety of animals? I can find numbers for some end points like hummingbirds and anacondas, but for most animals I can't find much data. Thanks.


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  3. #2  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Does anyone know the percentage of body weight any one animal needs to consume? (Other than large constrictors or hummingbirds.)


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  4. #3  
    Forum Professor Zwirko's Avatar
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    Try the following search on Google:

    food intake X, where "X" equals the animal you are interested in, then dig around in the results. Searches using words like "diet" etc can help too.

    Perhaps you could name some critters that you are interested in specifically?
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  5. #4  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Ah, thanks. Knowing the right terms helps some.

    Anyway, I'm not exactly looking for any specific animals, but a variety of different animals. I'm trying to work out a method for (roughly) calculating how much a (possibly fictional) animal would eat per day, and I need some more data points for comparison. I think spiders and cows (for two) would be fairly different from snakes and hummingbirds. (To test my method, I'd guess that a trap-building spider weighing 1/10 of a pound should eat, on average, about 5% of its body weight per day, but I haven't found any real-world numbers for that yet.)
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    Forum Professor Zwirko's Avatar
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    Spiders are weird. They can go months without eating, some even for up to two years without eating anything at all. For an animal that lays a trap and then waits for food to come to it, times of feeding are highly irregular. Juveniles probably need to a lot more regularly.

    I quickly looked at one paper on tarantulas. They were fed 25% of their body weight once a month. This was enough for them to gain weight and grow.
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  7. #6  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Ah thanks. That's the kind of numbers I'm trying to find. So my prediction is too high. A trapping spider should need a bit less food than an active predator like a tarantula. I wonder which of my numbers are so far off?

    My equation is 1.25 * (factor1 * factor2 * ...) * (mass in lbs)^(-1/4), where there are 9 factors. For a hummingbird, the product of the factors should come out to 1, and for a large snake, they should come out to 0.01. You numbers suggest that for a tarantula, they should come out to 0.005 (if the adult weight of the tarantula was about 0.15 lbs). Right now, it's 0.03, so I need to fiddle with things a bit.
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  8. #7  
    Forum Professor Zwirko's Avatar
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    I don't think you can come up with a formula for such things and you'll likely end up comparing apples and oranges.

    For example, not all food has the same nutritional quality. Eating grass means you have to eat rather a lot to extract enough nutritional value to survive. Whereas digesting the insides of a mouse and sucking out the gloop has more bang for the buck. The organisms metabolism and lifestyle would also be important.
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  9. #8  
    Forum Radioactive Isotope MagiMaster's Avatar
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    That's what all the different factors are for. And I'm not really worried about the results being perfect, just somewhat close. (Maybe a little closer than 6x too high though.) The factors I've got are: feeding method, locomotion, temperature regulation, brain-power, covering, strategy (K/r), breeding, mating habits and society structure, though the last two are counted as very minor.

    Quick side question: are spiders warm-blooded, or do they only have partial temperature regulation?

    Edit: Looking around, it looks like spiders are cold-blooded. That, and a few more tweaks, gets my estimate for them down to 3%. I think that's probably close enough for now, but let me know if you want to look over the tables.
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