Since there are living beings (like moth larvae) which feed on textile fibers (wool, cotton, silk, et cetera), I was planning to introduce a human-sized creature with such feature, plus the ability to feed on artificial fibers as well.

Said creature should have a life cycle of at least 20-50 years, should feed exclusively on textile fibers, and would need about the same energy as a human being (~1500-2000 kcal/day).

Is there any scientific biological mechanism which could make this possible?

If hard-science fail in this case, even an "handwavy-but-interesting-solution" on the creature's supposed biology goes ;)


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    $\begingroup$ I love this question. Such an interesting idea. $\endgroup$
    – Green
    Aug 15, 2015 at 21:22
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    $\begingroup$ Was this question inspired by your dog eating your shoes or your cat eating socks?? $\endgroup$
    – Mystra007
    Aug 17, 2015 at 20:36
  • $\begingroup$ @Mystra007 No, no :D Even if I have a really difficult-to-handle-serial-mice-and-lizard-killing cat, fortunately I have never had such problems XD $\endgroup$ Aug 18, 2015 at 7:13
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    $\begingroup$ @AndreaJens, thank you for asking this question. It is still one of my favorite question/answer combos, over a year later. $\endgroup$
    – Green
    Sep 22, 2016 at 12:22
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    $\begingroup$ @Green Truth be told, I can say exactly the same :) At the very end, I've even introduced a character like this in one of my stories, even though I mixed in a bit of normal food as well :) $\endgroup$ Sep 22, 2016 at 13:21

1 Answer 1


Yes, but....

Wool is mostly keratin and cotton is mostly cellulose so your creature's protein and carbohydrate needs may be met in this way. However, fats are an essential component of human diets and those don't occur in any significant quantities in wool or cotton.

It's the little things

The human body needs many minerals that cannot be synthesized. Calcium, iron, selenium, and others are needed on a regular basis or basic metabolic functionality may be impaired. No iron == No oxygen transport. No good. Some  vitamins and some a few amino acids can't be synthesized either and must be consumed.

But my monster is special...

Building your monster so it can synthesize all the amino acids and vitamins it needs to function still leaves the problem of minerals and fats.

An interesting possibility is to get the needed minerals from the dyes used in the wool or cotton. Perhaps green dyes contain copper as the primary colorant, so when the monster is low on copper, it will develop a powerful craving for green cloth. Dark red or black cloth contains iron.

Further, dirty/used clothing may be more useful than clean clothes as worn cloth have salts, carbs, or some proteins embedded in them. This makes this monster the literal Sock Monster that causes the disappearance of the odd sock after a load of laundry.

Fats could come from oilskins which contain larger quantities of fats than normal cloth. Also, unprocessed wool has lanolin oil on it though perhaps not in sufficient quantity to satisfy any significant dietary needs.

Getting enough calories may prove expensive because wool is definitely not cheap after weaving. Cotton is cheaper but still not cheap when you need it every day. Unprocessed wool and cotton may be a viable food source.

Junk Food!

We want junk food! Junk food! Wool and cotton are boring! I'm not sure of the chemistry of how to do this but your monster could use the long hydrocarbon chains found in plastics as stock for conversion to fats. But! Plastics often have some funky other stuff embedded in the so eating too much of them may cause er, side effects. Definitely something you don't want to eat all the time.

Humans and animals in general don't use hydrocarbons as fuel because there just isn't much of it on Earth's surface. Normal carbs, fats and proteins are much more common so evolution made us to consume those instead of higher energy petroleum products. Life is amazingly flexible in what it can use for fuel. You could include a kind of symbiotic relationship between the monster and some gut bacteria that consume the hydrocarbons in plastics then convert them to lipids. (Heh! Antibiotics make you starve by killing off that gut bacteria.)

Checking on Chemistry SE would be a good place to sanity check conversion of long chain hydrocarbons to lipids.

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    $\begingroup$ It'd be interesting to have a culture where purple is the color of royalty, not because its a rare dye, but because it's so nutritious that only the royalty could afford to properly protect a purple garment from certain destruction. $\endgroup$
    – Cort Ammon
    Aug 15, 2015 at 22:15
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    $\begingroup$ @AndreaJens what this creature needs to survive is highly dependent on how close to human nutritional needs you want to stay. A human needs a couple grams of calcium every day, which is a lot of dye. 'Course, you could just handwave all that. I think the idea is different enough and compelling enough that they would suspend their disbelief. Nutritionists will roll in their graves, but you can't keep everyone happy. $\endgroup$
    – Green
    Aug 16, 2015 at 2:00
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    $\begingroup$ @Green: your answer is truly what I was looking for :D Accepted ;) Thanks again ;) $\endgroup$ Aug 16, 2015 at 20:19
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    $\begingroup$ My pleasure. :) $\endgroup$
    – Green
    Aug 16, 2015 at 20:47
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    $\begingroup$ I just want to point out that lipids can actually be synthesized using sugar. en.wikipedia.org/wiki/Fatty_acid_synthesis. While there are some essential fatty acids that humans cannot synthesize, the proposed organism could be capable of synthesizing them. It's essentially the same problem as the amino acids and your answer already handwaved that away. $\endgroup$ Aug 17, 2015 at 22:43

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