What is the Trophic System?

The trophic system is a way that ecologists try to understand how nutrients move through the biosphere.

What does that mean?

Well–I’m made of material, plants are made of material, fungus on the ground is made of material. All of these are basically bio-chemicals, right? The chemicals in our bodies that compose us and allow us to be biological machines. Well what happens when I die, or when the leaf dies, or when the butterfly falls to the floor? There are processes by which all matter, all nutrition–all the stuff that made up those nutrient-based life forms–this stuff gets cycled back into something else. In science we’ve sorted out these relationships in different levels called the Trophic System.

We’ll discuss each of these separately, but in short,

The various levels of the Trophic System are:

  1. Producers
  2. Primary Consumers
  3. Secondary Consumers
  4. Tertiary Consumers
  5. Detritivores (Decomposers)

This is a simplified diagram, but you can see how matter concentrates as it moves up the pyramid. It should be noted that energy is lost as it moves up the system, but this subject will be discussed in a separate article.

Here’s another image to visualize the Trophic System:

Energy (in the measurement of Joules) is lost as you move up the trophic system.

Energy (in the measurement of Joules) is lost as you move up the trophic system.

Trophic system can be thought of like a pyramid. The pyramid has a base, and the base is held up by Producers: that’s plant-stuff. Every mobile multicellular organism, like you and I, that has to eat something else, is called a heterotroph. A heterotroph is an animal that cannot produce its own food—we have to go eat other things. Every heterotroph in some way or another relies on plants. Plants are autotrophs. They take energy from the sun and are able to produce carbohydrates on their own.

Because of this, plant life is the base of all other living things — plants are what sustains all animal life. These make up the bottom piece in the trophic system and because they “produce”, we call them Producers.

The second level in the Trophic System are “Consumers”.

Consumers eat the plant-stuff. There are different levels of consumers, an herbivore, for example (a vegetarian), is going to be called a Primary Consumer. A primary consumer is one step away from the sun–it eats the plants. The earth grows grass, a cow eats the grass, and it goes on living to build its tissue.

So, these consumers, whom only feed off of plants (herbivores) we call Primary Consumers.

Secondary Consumers

Now you and I, we like to eat a hamburger (a cow), or an animal like a wolf might enjoy eating a cow also. We call an animal that eats an herbivore, a carnivore. Because a carnivore is two steps away from producers, (Producers > Primary Consumers > Secondary Consumers), we call them Secondary Consumers.

The carnivores rely upon the consumption of another vegetable eater, whom ultimately is relying on the Producers (the plants), whom is ultimately garnering its energy from the sun. Cool, huh? The plants ate the sun to build their bodies, they cows ate the plants to build their bodies, and now I’m eating the cow to build my body. This saves me a lot of time by comparison if I had to eat all of that grass myself.

With human beings, we can choose to become a vegetarian for example, and eat straight to the plant base. Many human beings believe this to be a better diet to avoid some of the health risks involved with eating meat. Other nutritionalists argue that a healthy diet balanced with meat is important for human nutrition. These are personal and ethical choices that we as human beings can choose to make on our own.

However, in nature, most animals eat whatever they can to survive. Thus, the relationships we have been discussing here today.

Tertiary Consumers

The cycle goes on and on. Because an animal could say, kill and eat me after I ate my hamburger, or say a shark might eat a bigger fish whom had just eaten a smaller fish, there can be what’s called, Tertiary Consumers. If a bear ate me, it would be a tertiary consumer. The cow eats the grass, I eat the cow the bear eats me. That’s three steps away.

Decomposers and Detritivores

Well what happens when the bear dies, or me? There are tons of bacteria and microbes (even in the own body). More than even the microbes, there are other living things such as fungi whom feed off of dead matter. These are called Detritivores This includes bacteria, fungi, and small insects.

A carrion-eating bird for example, might still be considered a secondary consumer, although these are the ‘fuzzy’ areas of science that show how difficult it truly is to categorize and understand the relationships surrounding life on our planet.

Detritivores bring the cycle back to the beginning.

When a plant falls to the ground detritivores eat it. When I die, I’m eaten by them. The earth-stuff that had been captured in my body during my entire life is freed by these organisms into usable nutrient forms for other life forms to take up.

Detritivores encompass the entire trophic system and they are what brings everything back around full swing. They turn a dead organism back into the stuff of soil, that ultimately become once again, plants.



Another simplified diagram. [Source]


This is a more complex diagram, again which does not take account energy, but shows the complexity that is involved in various trophic system relationships.

So thats what we call the trophic system.  Its a hierarchy of how nutrition and physical matter moves through biological systems, powered by energy. Always remember that matter cycles, I turn back to soil, soil turns to plants, plants turn into animals, animals turn back into soil, and energy flows through these systems, being used up through the process. I may write another article explaining the linkage of energy to the trophic system–this would be helpful and I don’t want to diverge this essay here onto another lengthy issue, but please note that energy and matter are not the same, and this article discusses the motion of strictly matter.

All of this stuff just keeps cycling. And an interesting take home is to consider your finger tip. One of the carbon-molecules making up a single skin cell on the tip of your finger has a life you wouldn’t believe. If you could trace it back to the origin of its creation, we might see it as a part of your breakfast sandwich a day prior, before that a molecule trapped in the soil in an industrial tomato farm that was to be a future part of your sandwich. Before that, it may have been in the body of a worm, and before that, it may have been a part of a leaf that the worm was just about to eat. The cycle goes on and on.

This is the true beauty of understanding the Trophic System and how this concept can help us to better understand the relationships of matter within the biosphere. Inorganic matter housed in our Earth moves through different levels, travels as a part of different biologic units, before being recycled back around again. The forces that power an shape Earth and these processes are interesting and wondrous indeed.