Discovering Earthworms Online

Author

Keiron Derek Brown

During May and June 2021 the Earthworm Society of Britain and the Field Studies Council ran their first-ever Discovering Earthworms online training course. The course was developed and delivered by myself and Kerry Calloway, with learners working their way through study content, activities, assignments and live webinars across 4 modules. This blog will give a taster of what our learners covered and report back on the results of their field assignments.

Earthworm Biology 

This module covered what makes an earthworm an earthworm and where earthworms fit within the tree of life. It provided an introduction to the biology of earthworms, including their anatomy and some of the biological processes occurring within the earthworm. For example...

Earthworms are segmented worms and are classified as belonging to the phylum Annelida. Other annelids include bristle worms, leeches and pot worms. Below is a diagram explaining a simplified breakdown of annelid taxonomy.

Diagram illustrating some of the groups within the phylum Annelida.

Earthworm Ecology & Behaviour 

This module explored the role of earthworms within the ecosystems that they inhabit. It started with the findings of Charles Darwin regarding earthworm intelligence and the role of earthworms in bioturbation. We then moved on to various behaviours of earthworms, including burrowing, dormancy and dispersal. For example...

The burrowing behaviour of earthworms provides ecological benefits (known as ecosystem services) to the wider ecosystem, with earthworm's often described as "nature's plough".

  1. Aeration of the soil Burrows penetrate the soil and burrowing activity moves it around through bioturbation. This facilitates the infiltration of air into soil systems. Deep-burrowing earthworms create channels from the surface deep into the soil and shallow burrowing earthworms move around within the upper layers of the soil profile. Combined, this creates an extensive network of underground channels through which air can circulate. Aeration of the soil is important for other soil organisms, including aerobic bacteria.

  2. Soil drainage In much the same way that burrowing facilitates aeration, it also facilitates the passage of water through the soil by creating channels through which water can flow. This helps water drain through the soil profile when deposited as rain and improves the water retention capacity of the soil.

  3. Decompaction and soil penetration The burrowing behaviour of earthworms decompacts the soil as they move through the substrate. This enables other organisms (including micro-organisms) to access the soil. Burrows also facilitate root penetration into the soil by providing a “path of least resistance”.

  4. Movement of material and organisms When earthworms burrow through the soil they transport soil particles, organic matter and microorganisms as they move. This redistributes resources throughout the soil.

Earthworm burrows
Left image: Earthworm emerging from burrow (c) Frank Ashwood. All rights reserved. Right image: Earthworm burrows in soil © Keiron Derek Brown. All rights reserved.

Earthworm Diversity 

This module explored how British and Irish earthworms can be categorised by their ecology and behaviour into 4 ecological categories, with guidance on how to determine the ecological category an earthworm belongs to in the field based on the size, colour and pigmentation of an earthworm. It looked a little further afield and discussed the diversity of earthworms globally, with a look at some amazing species found outside of the British Isles and the impact of British & Irish earthworms in ecosystems they have been introduced to abroad. For example...

Did you know that the Giant Gippsland Earthworm is the world's largest known earthworm species? It can grow over 2 metres in length and is a protected species in its native country (Australia). David Attenborough tells us more in the video below...

Finding Earthworms 

This module put the things that we'd learned about earthworms into practice. This involved completing 3 field assignments and reporting back our findings...

Field Signs Evidence assignment

Each learner was tasked with locating an earthworm field sign and submitting a photograph (or sketch) of their finding.

Earthworm field signs submitted by students
Left image: Earthworm cocoon © Anke Marsh CC-BY. Right image: Earthworm midden © Jennifer Ball CC-BY.
Earthworm field signs submitted by students
Left image: Earthworm casts © Christine Adams CC-BY. Right image: Earthworm burrows © Sarah Patton CC-BY.

Microhabitat Search assignment

Learners reported back which ecological categories of earthworm they found in various microhabitats. The top 4 microhabitats surveyed were leaf litter, compost, deadwood (within or under) and under non-deadwood items. The bar chart below displays the results for these microhabitats and tells us:

  • Leaf litter favoured epigeic earthworms, with no anecic earthworms found in this microhabitat at all.
  • Compost (unsurprisingly) favoured composting species but was still home to the other 3 ecological categories of earthworm.
  • Endogeic (shallow-burrowing) earthworms were the ecological category most commonly reported as present overall.
  • Deadwood was great for finding diversity when it comes to the earthworm ecological categories.
Bar chart of top 4 microhabitats surveyed and the breakdown of the ecoogical categories of earthworm recorded

Soil Pit Survey assignment

Learners sampled a soil pit in their garden or allotment and reported back on the number of earthworms they found, broken down by ecological category and adult vs juvenile. The pie charts below display the class results and tell us:

  • Across 71 soil pits, 890 individual earthworms were recorded - an average of 12.5 earthworms per soil pit.
  • Endogeic (shallow-burrowing earthworms) made up the highest proportion of earthworms recorded by far, with over 70% of all earthworms recorded belonging to this ecological category.
  • Anecic (deep-burrowing) earthworms accounted for just 12% of earthworms recorded, despite being the 'typical' earthworms that most people think of when they hear the term earthworm.
Pie charts showing breakdowns of earthworm ecological categories by juvenile, adult and total from soil pit surveying.

 Learner feedback

I particularly enjoyed the units on earthworm diversity and ecological categories which gave me a greater appreciation of signs and earthworm activity and broad categorisation of worms I see when gardening. I’ve always been very interested in the dynamics of worm populations in compost bins and actively manage three composting systems to optimise the composting rate.

I’d certainly recommend this course for anyone managing an allotment or gardening for vegetables at home. With the popularity of both these activities for mental health/exercise during lockdown and self-sustainability post-Brexit, I would think these excellent target groups to engage.

Leon Stone

"I thoroughly enjoyed the course Discovering Earthworms. Before joining the course, I knew little about earthworms. In March 2021, I discovered that my allotment was contaminated with Australian flatworms (a non-native earthworm predator) and I was concerned about how the earthworm population would be affected. When desperately searching the internet for a solution to control the flatworms, I came across the FSC and a wide range of courses it offers including the one on earthworms.

Through the course, I learned the earthworm’s biology, different groups of earthworms and their contributions to the ecosystem. The course showed me that earthworms are among those most important, incredible, and fascinating creatures on earth! I also learned the different negative factors that could impact on earthworm population and the method of sampling and monitoring earthworms in the soil. The course has certainly motivated me to learn more about the earthworms and do things differently to support the earthworms to survive and thrive."

Yan Wang

"Discovering Earthworms gave me a huge affection for worms! And the assignments were a real eye-opener into the condition of the soil in my garden. I was kind of disappointed not to have more anecic and epigeic worms when I try to be so ecologically friendly. I haven’t been very religious with my mulching and my soil was quite sandy and dry so I will definitely be trying to build up the population in my garden by putting down more mulch.

I love now knowing about the different types of worm, I’m able to tell juveniles from adults, the amount of work and the webinars were all the right sort of length.
It’s made me think about conservation. It’s made me sign up for other courses. I have now considered becoming a conservation volunteer. So much more interesting than being an accountant."

Lesley White - Wildlife enthusiast, gardener for wildlife, animal lover

Discovering Earthworms promo imageDiscovering Earthworms Online
Round 2

We're pleased to report that, due to popular demand, we've decided to run the Discovering Earthworms Online course a second time this year. Again, the course will be available to ESB members and non-professionals in the UK for just £20 for this 4-week course. Find out more and book via the Field StudiesCouncil website:

https://www.field-studies-council.org/shop/courses/discovering-earthworms-online-2/

 

Creative Commons License
Except where otherwise indicated, this work was created by Keiron Derek Brown on behalf of the Earthworm Society of Britain and is licensed under a Creative Commons Attribution 4.0 International License.