Trophic Levels and the Leafy Gold Mine. Plant Life is Life. –

Trophic Levels and the Leafy Gold Mine. Plant Life is Life.

7 mins

The numbingly academic-sounding "10% Rule of Energy Transfer" keeps nearly a billion fellow Earthlings starving on their feet. Plants are more than leafy amusements for the windowsill. Plants can end global starvation. This is simple biophysics. It's now a question of will. 

Table of Contents

Let’s begin at the beginning. The sun blasts the Earth with solar energy, which fuels all Life on Earth. The crazily beautiful diversity of Life on Earth (some of which will ravenously eat you as you stand and admire it) is only possible because plants turn sunlight into food. 

Animals (herbivores) then eat the plants for energy, and those animals are in turn eaten by other animals (carnivores) who prefer meat to salad.

This has been called the Circle of Life, but it may make more sense to call it the Terrified Footrace of Life — a theme Disney™ is understandably hesitant to put into song.

All this eating (energy consuming) proceeds “upward” to what is humbly called the ”top of the food chain” — so-named by the self-congratulatory human race that occupies that lofty summit. Woo hoo! Hand me my crown! Glass half empty: by the time we “apex” animals get our share of energy, it’s been turned into a bargain basement shadow of what it once was.

Planting the Flag

There are a few things we remember from school (he over-generalized). Trophic levels and ”biomass transfer efficiency” — as powerfully exciting as they sound — may not be part of your fond academic remembrance.

But these eye-opening rules of biophysics go a long way toward explaining why we grow enough food to feed 10 billion people — and still have nearly a billion fellow Earthlings starving on their feet. Not to beat a worn drum, but the plant kingdom is our world’s nutritional salvation. This is simple biophysics.

Energy Distribution = Maddening Waste

Here’s a loaded word: Energy. In terms of Earth’s natural history and the life currently swarming our planet, energy enters our ecosystem as sunlight. This is stating the obvious, I know. But how the sun’s energy gets handed around once it gets here is like a screwball comedy.

The sun slams our spinning rock — our planet, that is — with 430 quintillion joules of energy from the sun every single hour. That's a little more energy than global humankind uses in a year.

As has been stated in these pages, our planet conveniently rotates on its axis like a rotisserie chicken, such that every square inch of the place gets painted by the solar energy flying off this conveniently located lamp (the sun) in the middle of this otherwise freezing room (our solar system).

It’s a fortuitous setup for living things, considering there were no living things at the time of the Big Bang (as they call it with straight faces). But we’ll leave it at that

The Big Kapow, or whatever they call it. One of the more generous explosions on record.

If Earth is receiving more energy every hour than we use in a year, what’s the problem? The problem is that the story of energy is largely the story of how this magic stuff gets frittered away by the well-meaning systems that depend on it.

Life is a system, for instance. An ecosystem. Earth’s plant kingdom is first recipient of all that incoming solar energy. As you move up the energy chain from there, the story is of pure loss. The phrase “eat your vegetables” is overloaded with wisdom.

Energy Sieve

Life may be a near-miracle, and justifiably the subject of song and science, but life is also this big messy thing energy has to flow through. Life as a labyrinthine energy filter is a mess. Energy is the famously animating principle of life, but is leaking wastefully out of every seam the ecosystem can provide.

By the time the bugs get hold of it, the original energy has already lost 90% of its zing. And we humans are still several levels up! How are we going to get food to all the world’s humans at this rate?

Spoiler Alert: we’re not.

Producers and Laggards

So the sun is throwing off energy like crazy, and that solar energy races across the 93 million miles that lie between us and the sun, slams into the hearth and starts working its way through the living kingdoms.

When sunlight strikes a leopard, snail, porcupine or platypus (*had to include the platypus) what happens? Not a hell of a lot. Some animal’s back gets pleasantly warned, maybe. When sunlight strikes a plant, though, the sunlight gets turned into food.


The plants that carpet this world are not only the first stop of solar energy when it smashes into Earth, plants are the only Producers in earth’s food chain. Plants don’t have to chase their food, they make their own food when they take in sunlight and photosynthesize.

As producers, plants are the advance guard of the ecosystem. Once plants turn sunlight into food, the whole shebang gets started and the energy that drenched the plant kingdom starts heading up the food chain.

Trophic Thunder

So yeah. Plenty of happy talk about energy being all over the place. Plants are thus the first trophic level, and are followed by life forms that need to catch their food. It looks like this:

  • Producers — Plants eat solar energy and turn it into food through photosynthesis. They don’t need other animals to get their energy. Plants make their own food.
  • Primary Consumers —plant eaters 
  • Secondary Consumers — meat eaters preying on the plant eaters
  • Tertiary Consumers — these folks eat secondary consumers to get their energy.
  • Apex Predators (Consumers) — those at the top of the food chain: wolves, lions, orca, and hedge fund managers.
  • Decomposers — When an animal in the wild has the unlikely good fortune to die of old age without having been eaten, fungi and bacteria get busy turning the dead beast into mulch, where it helps nourish the root systems of sun-eating plants and starts the whole energy cycle thing over.

*I know what you’re thinking. “That cashier at the pet shop down the street is an apex predator?”



So the big shots are at the top of the food chain, while down there at the bottom are the dumb ol’ plants. Ha ha ha ha! Those poor helpless plant fools. Ha ha ha ha!

Hold on.

Producers are the Answer

Plants turn sunlight into food so all the other living things on earth, things with teeth and stomachs, can get the energy into themselves and go on living -- and eating, of course.

But as energy moves up the food chain from the Producers — plants — it dissipates. Big time.

You may have read in these hallowed pages that 20,000 calories worth of corn feed eaten by a cow becomes 2000 calories when you actually eat the cow. It’s true. In fact, as you rise through the trophic levels from plants to apex, you lose at every level about 90% of the caloric energy. Hence the bovine example above: 20,000 calories in, 2000 calories out.

This is because not all the energy consumed by an organism will be made available to the next guy in line up the food chain. Energy is not just passed up the line, it is used by the recipient animal.

The energy it eats gets used for reproduction and growth. Cellular respiration also dissipates a bunch of the consumed energy as heat, and when an animal leaves waste material there will be a quantity of energy in that material, too. Just ask the Dung Beetle (if it answers, get help...)

In short, you can dump lots and lots of calories into a farm animal, and we do.

But when you eat the animal you will only be getting a ~10% caloric/energy return. 

This is called the 10% rule of energy transfer. This isn’t a problem you will particularly feel as you dispatch your steak dinner. This is a problem felt by those who have very little (or nothing) to eat because the vast stores of high-octane plant energy have been given to cows, pigs, and chickens.

To put this in the starker terms of global hunger — if you have an acre of grain, you can feed it to cattle, and then the cattle can be fed to hungry people. 90% of the grain energy is lost to the cattle. 

This means (among other things) you could get caloric energy to nine times the number of people if you just fed them the grain directly; and not the cow that ate the grain.

Another way of looking at it: you would only need 1/10th an acre of land to feed the same number of hungry people grain as you could feed with a full acre's worth of cows. Think.

Jump Over the Cow

Most of us have heard the old nursery rhyme that features a cow jumping over the moon. More profoundly important is the idea of jumping over the cow and going straight for the grain. All the necessary riches are in the grain.

The plant life that carpets this planet is sufficient to feed us all. Meat is basically a strainer that strips caloric energy from the system, offering a lousy return on an ill-advised investment -- and keeping nearly 828 million people (at last count) starving for lack of food.

For instance, a cereal crop is a type of grass containing considerable food energy. Wheat, rye, oats, and barley are examples. 

Globally, cereal crops provide more energy than any other crop. Cereal crops are absolutely central to feeding the humans of Earth. 

But at present, less than half of the world’s cereal crops are eaten by humans. 41% is used for animal feed, and 11% for biofuels.

Family is All

Carnivore? Vegetarian? Vegan? Flexitarian? Time to act like a family. Let's get intentional and rescue ourselves. Of all the reasons to pass from this world, absence of food is the most idiotic and preventable. IT SIMPLY DOESN'T HAVE TO BE. Let’s do this.

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