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Robin Food: How Many Calories in a Worm?

Not that it matters to anyone but a robin, but how many calories are in a worm? How does anyone figure out the answer to a question like this? We didn't know, so we consulted with Cynthia Hale, a forest ecologist and graduate student at the University of Minnesota. Cynthia's educated estimate for an average worm having a dry weight of 33 mg is 0.7 nutritional calories. How she figured it out might matter to YOU, so Cynthia explained her calculations:

  1. Using the information I got off the nutritional label of a bottle of protein powder, I learned there are 3.75 Calories per gram of protein. I already knew this:
    * 1 Calorie (capital C) used in nutrition = 1,000 Kcalories (Kcal).
    * 1 Kcal = 1 calorie

    * A calorie (small c) equals the amount of energy (in the form of heat) needed to raise the temperature of 1 gram of pure water one degree C (for example, from 14.5 C to 15.5C).

  2. The average dry weight of one of my earthworms was 33 mg, or .033 grams.
    So .033 gr X 3.75 Cal/gr = .124 Cal/worm

  3. Oops! Only 60% of the worm is protein. So, .124 X.60 = .07 Cal / worm.
    (Note: Because a worm has other molecules, like starches and sugars, that contain calories, you could increase this a tiny bit if you wanted to.)

  4. .07 Cal/worm X 1,000 Kcal/Cal = 70 Kcal/worm

Got it?



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