When people think of worm composting, they tend to think of…well…worms! Many go so far as to assume that most of the other living creatures that show up in a worm bin are to be frowned upon, if not eradicated.
That couldn’t be further from the truth! A well-functioning vermicomposting ecosystem is one with a rich diversity of organisms, all working together in different ways to help the process along.
In this article - the first in our new macro-invertebrate series - we’ll provide an overview of the organisms called “invertebrates” - primarily zoning in on the main groups of importance for us worm composters (and really, composters in general). We’ll be starting with a - relatively-pain-free, we promise - lesson in invertebrate taxonomy, just so you can see how the organisms relate to one another and fit into the broader group of “animals” as a whole.
The reason scientific classification is important is because it helps to keep things more standardized (consistent and reliable). As a couple of quick examples, look no further than the terms “worms” and “bugs”. Let’s face it - these are both used regularly to refer to a lot of different organisms - many of them completely unrelated!
Don’t worry, though - a full-fledged, deep dive into scientific classification isn’t really necessary for our purposes. This is more of a “10,000 foot view”, just to help you get a better handle on things.
OK, before we dig in with the official hierarchy of itty bitty critters, we should probably start with the somewhat more informal term “invertebrates”. This refers to organisms that don’t have a backbone or, really, any sort of organized, internal skeletal structure.
Most invertebrates tend to be quite small - including all the ones we’ll be focused on - but there are definitely some exceptions to the rule (e.g. Giant Squid)!
There is also some gray area in terms of what all falls under this category. Protozoans (like Paramecia and Amoebae), for example, are technically invertebrates - but they are also microorganisms. To help keep things as simple as possible we are using the term “macro-invertebrates” here - so as to stick with the invertebrates you can see with the naked eye.
Getting back to our classification lesson…
All invertebrates are in Kingdom Animalia - but this doesn’t really help us at all, since we are too - as are lions, whale sharks, and chipmunks (among countless others, of course).
Phylum is where things start to get a bit more exciting! All those examples from the last paragraph? Yep, we can separate them out into their own phylum: Chordata. Pretty funny to think that most of the organisms we tend to think of as “animals” can be found in that one, comparatively small, group.
How small, you ask? Only 10’s of thousands of species. If that sounds like a lot, consider the fact that invertebrate species number in the millions (with many more still thought to be undiscovered). According to National Geographic, it is estimated that invertebrates make up as much as 97% of all the animal species on earth. So yeah, they are kind of a big deal!
Fun facts aside, let’s zoom in on the key invertebrate phyla of interest for us worm composters!
Annelida
These are the segmented worms, including the earthworms and enchytraeid worms (pot/white worms). Although composting worms are referred to as “earthworms”, it’s always important to remember that they are highly specialized for an organic-waste-rich environment (not soil).
Arthropoda
This is an incredibly important phylum that includes all of the insects, crustaceans, spiders, mites, millipedes and centipedes, along with various others. Invertebrates in this group all have some form of exoskeleton - a thick, protective outer covering, made of chitin.
Nematoda
This is also a very important group, but most people won’t really see them with the naked eye, so they tend to be treated as microorganisms.
Mollusca
Snails and slugs are the groups of interest in this phylum, They tend to only really make their presence known in outdoor systems.
Platyhelminthes
These are the flatworms. This is one group we typically don’t want to see well-represented in worm composting systems, since some species can be voracious earthworm predators. The good news is that unless you live in a tropical or semi-tropical climate, you are unlikely to encounter the real troublemakers of the group.
OK, let’s now break things down a bit further, so you see how the key (vermicomposting) players fall within these big groups, and relate to one another. (We’ll leave nematodes out at this point, since - as touched on - they tend to be considered a microorganism).
Phylum Annelida
Class Clitellata
Order Opisthopora - all the earthworms, including the composting species
Family Lumbricidae
Genus Eisenia (Red Wigglers, European Nightcrawlers)
Order Tubificida - white worms (aka pot worms)
Phylum Arthropoda
1) Subphylum Crustacea
Class Malacostraca
Order Isopoda
The isopods - common names: woodlice, sow bugs, rollie pollies
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2) Subphylum Hexapoda
Class Insecta - The insects - “true flies” (most flying insects, and larvae, we find associated with composting systems), beetles, earwigs, “true bugs”, moths and larvae (rare in this environment, but there are some)
Class Entognatha - Springtails
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3) Subphylum Chelicerata
Class Arachnida
Superorder Acariformes - Mites
Order Araneae - Spiders
Order Opiliones - Harvestmen (‘daddy longlegs”)
Order Pseudoscorpiones - pseudoscorpions
—
4) Subphylum Myriapoda
Class Chilopoda - centipedes
Class Diplopoda - millipedes
Phylum Mollusca
Class Gastropoda - snails and slugs
Phylum Platyhelminthes
Order Tricladida
Genus Bipalium (again, most composters in temperate regions won’t encounter these)
So, there you have it - a decent overview of the main groups of invertebrates found in a worm composting system. Don’t be fooled by the fairly short list, though - some of the groups are very well represented, with many different families and genera making their presence known.
Upcoming articles in this series will focus on the key invertebrate players that show up in vermicomposting systems, including springtails, mites, isopods, various types of insects, millipedes/centipedes, and of course the annelid worms!
Admittedly, some of these critters are considered “pests” (and understandably so), but our hope is that by developing a better understanding of these different groups, more people will come to realize the important role many of them can play in our worm bins!
Other Articles You May Be Interested In
Springtails - White Plague or Worm Ally?
How to Feed Your Worms to Get The Best Results From Your Worm Bin
Smelly Worm Bins - Possible Causes & Effective Solutions
What Is “Living Material”?
Bedding - The Most Important Material in Your Worm Bin?
DIY Plastic Worm Composting Bins
Recommended Products
Hemp Worm Blanket
Red Wigglers
Worm Starter Kit
Worm Rake
pH Buffer Grit
BioChar