Roughly speaking, a small, complex electronic circuit or IC might sit in "sleep mode" using a current of roughly 1 µA (e.g. 1, 2), thereby using roughly $3\times 10^{-6}$ Watts, and that converts to roundly $2.5\times 10^{-6}$ kcal/hour or $62\times 10^{-6}$ kcal/day.

I suppose you could call that 62 micro-kcal/day or 62 milliCalories/day.

One day I noticed a small spider in my home, sitting in its small web, and kept an eye on it. After several weeks of watching I hadn't seen it catch anything. I slightly perturbed the web and it reacted. It was still alive.

Question: I'm curious to know roughly how much energy a small spider needs to sit and wait. Might this be termed roughly the spiders Basal metabolic rate?

I have read about Kleiber's law in this answer but I don't think it is meant to extend down to small spiders.

note: I'm just asking for the energy expended during resting periods. Of course during a day the spider may do web maintenance or actually catch or eat something, but it's the resting rate of energy consumption, on a daily basis, that I'm asking about.


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