Crafting a Complete Ecosystem with Getz’ Model

Ecology and biology are areas that I often overlook. This is a shame; they can lead to some very interesting worlds, such as Roshar’s crabs-are-everywhere approach in Brandon Sanderson’s Stormlight Archives series. The field of speculative evolution/biology is concerned with how things might realistically look in other environments, and every worldbuilder can benefit from studying it. One source that I enjoy is Sigmund Nastrazzurro’s blog, Furahan Biology and Allied Matters, and there are lots of books on the subject.

Personally, I find it hard to craft a complete ecosystem. While it’s obviously unnecessary to have a creature in every ecological niche, thinking of things in terms of systems instead of individual species can help to make an engaging setting. This article is written with that mindset in mind.

The Basics – Food Chains

Before we get into the good stuff, let’s get some basics out of the way. Food chains are a simple visualization tool that are used in schools to illustrate the flow of energy around an ecosystem. There are three basic layers:

  1. Producers Organisms that get energy from non-biological sources (sunlight, raw chemicals, etc.) – on Earth, almost always plants
  2. Consumers – Organisms that get energy by consuming living or recently-living organisms. Roughly divided into three categories:
    • Herbivores – Eat producers
    • Carnivores – Eat other consumers
    • Omnivores – Eat either producers or consumers
  3. Decomposers – Organisms that get energy by consuming dead organisms.

These categories are obviously hazy for a lot of reasons. Some plants supplement their diets by leeching off of other plants or consuming animals. The line between consumers and decomposers is blurry, as well. Are vultures decomposers or consumers?

Regardless, it’s a good enough place to start. To come up with an ecosystem, you start with an energy source, define the other characteristics of the habitat, move onto producers, add consumers, and finish with decomposers. There are lots of ways that you can make things unique, including unusual senses, body plans, and methods of movement.

However, what if you’re like me and want to make sure everything’s as complete as possible? Well, there’s a tool that can help:

Wayne Getz’ Biomass Transformation Web

In 2011, the South African ecologist Wayne Getz created a way to categorize just about every consumer/decomposer species out there. There are three dimensions he included:

  • Mobility – Whether the creature moves from place to place (“gatherer”) or stays at one food source (“miner”). This isn’t whether the creature can move at all, but whether it moves between food sources.
  • Trophic Level – Whether the creature eats plants or animals.
  • Decomposition Level – Whether the creature eats live organisms, dead ones, or the particles left over when a creature decomposes completely.

He summed all this up in a totally-not-confusing chart:

Getz’ Biomass Transformation Web; I’ve actually removed text, if you can believe it

All the dimensions are there. See?

Gatherers on top, miners on bottom
Plant-eaters on the left, animal-eaters on the right
Live creature-eaters on the outside, debris-eaters in the center, and dead-eaters between them

So this is… a lot. There are ten categories, which gives worldbuilders a lot to work with. Many creatures fall in more than one category, or shift categories over the course of their lives. In general, each ecosystem will have at least one creature feeding on each of these biomass sources. Species will specialize far more than their consumer categorization; koalas and pandas are extreme examples that most people are familiar with, consuming only one specific plant each (eucalyptus and bamboo respectively).

To make things clearer, let’s finish up with some examples:

Gatherers – Mobile Consumers

Deer, Victivores – Mobile, live plant-eaters
Tigers, Bestivores – Mobile, live meat-eaters
Beavers, Lectivores – Mobile, dead plant-eaters
(yes, they do eat some of the wood)
Vultures, Carcasivores – Mobile, dead meat-eaters
Earthworms, Detritivores – Mobile debris-eaters

Miners – Stationary Consumers

Aphids, Zotanophages – Stationary, live plant-eaters
(there aren’t a lot of true zotanophages, but this is close)
Tapeworms, Sarcophages – Stationary live meat-eaters
Termites, Thanatophages – Stationary, dead plant-eaters
Maggots, Necrophages – Stationary, dead meat-eaters
Coral, Decomposer – Stationary debris-eaters

And there you go! A ridiculously-complex but extremely thorough way to look at all the niches in your ecosystems.

Do you have any creative creatures? Any feedback or suggestions? Love to hear them!


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