I was listening to an online lecture by Nick Lane. He has written a few books I’m interested in reading

He stated two facts about mitochondria that paint a vivid picture. For background, our cells have mitochondria which store energy as a charge across a membrane that is folded up inside the mitochondria.

1. If the mitochondrial membranes in a human body were stretched out they would cover 4 football fields.

2. If you added up their stored charge in one person, it would approximately equal 1 lightening bolt.

The imagery of one bolt of lightening powering all the cells in a human body is awesome. That seems a lot of electricity. I had always thought of metabolism in terms of calorie intake or burning: a rate of consumption or a rate of energy expenditure. But this fact made me visualize metabolism as a sum of all the batteries in your body.

Food → Mitochondria → ATP. This flow leaves a lot out but roughly that’s how energy flows to power our cells. I like Dr. Lane’s choice to quantify the stored charge in the middle.

I was curious how that figure, 1 lightening bolt, would compare to other creatures. The lecture was on the origin of life and thermal sea vents. I thought about cephalopods, sharks, shell fish, and worms. Start with the smallest.

I searched for data on earthworms. You see them in compost piles. They are great fishing bait. I wanted to find how much energy is stored in an earthworm. I took the answer, 10 joules, from this paper:

• 588.4 ± 55.1 J kg proteins

• 119.3 ± 15,6 J kg carbohydrates

• 369.6 ± 109.2 J kg lipids

…equals 1077.3 +- 179.9 J kg. The unit for that sum is “joules per kilogram of worms”. An earthworm’s mass is ~10 grams. 1077 J kg / 100 = ~10 joules in one worm.

An average bolt of lightening is 1 gigajoule. A gigajoule is 10^9 joules. You have approximately one hundred million worms worth of energy in your cells! Add that to your CV.

What is the surface area of one worm’s mitochondrial membranes? I don’t know. It’s less than 4 football fields. If it’s a linear function of energy:

4 football fields
x 5,500 meters^2 average football field
x 1/10^9
= 220 millimeters^2 per worm

That is 88% of a dime’s surface area.