Earthworm ID course - AIDGAP key launch

Author

Anthony Roach
ID course participants examine worms
ID course participants examine worms

I vividly remember as a child picking up earthworms, marveling at woodlice and exploring the dirt! I was always fascinated by the miniscule creatures in my garden. It is therefore no surprise to me as an adult I champion earthworms and other ‘small things that run the world’. I love invertebrates and personally feel humans take the presence of ‘bugs’ or ‘creepy crawlies’ as they burrow, crawl, buzz, fly, raft and swim for granted. Invertebrates make up 97% of all life on Earth and to me insects, crustaceans and other marine creatures are just as beautiful and should command our respect.

Invertebrates are so named because they lack an internal bony skeleton, have soft, squishy parts on the outside or are covered in an exoskeleton made of chitin or as in snails and other marine creatures can be covered in hard calcium shells. All life ultimately depends upon invertebrates whose ecosystem services pollinate the plants we grow for food, recycle waste and decaying plant material, improve the structure of and provide nutrients for soils and are a major source of food for wildlife on land and in our oceans.

Why should we care about earthworms?

Why should we care about earthworms? Well, earthworms are remarkable creatures. They have been around for at least 209 million years. A single hectare may hold as many as 8 million earthworms and worldwide there are around 6,000 described species. Earthworms alongside bacteria, fungi and insects are vital for recycling organic material (such as fallen leaves and rotting wood) to create the soils we need to grow food and provide food for all kinds of wildlife. Healthy soils are very important for supporting plants and animals on Earth as soils recycle nutrients, filter our water and allow us to grow our food. The soil also limits the effects of climate change by storing carbon in the form of tiny fragments of plants, microorganisms and animals in the soil. Without earthworms to maintain the health and structure of soils, plants and animals would be unlikely to receive the nutrients, water and food they need.

Earthworms can range in size from a few centimetres to Australia's Giant Gippsland earthworm which can reach to over a metre in length! In Great Britain and Ireland there are 31 different kinds of earthworms and they can be pale green, blue to deep red and stripy in colour. Some earthworms even glow in the dark (known as bioluminescence). Historically, compared with other wildlife such as birds, butterflies or mammals, earthworms have been very under-recorded.

Earthworms, like human beings have a brain, a nervous system, heart and a digestive system, as well as carrying blood around their bodies. Naturalist Charles Darwin famously studied earthworms for over 30 years and made some interesting observations about their senses. Find out more about earthworm senses and Charles Darwin’s experiments on the Earthworm Watch website.

Join the Earthworm Society of Britain

There has been a society devoted to bird conservation in Britain since 1889 - The Royal Society for the Protection of Birds. The Botanical Society of Britain and Ireland was established even earlier, in 1836 for wild plants. It wasn't until a century later in 2009, that the Earthworm Society of Britain (ESB) was set-up by passionate individuals to raise awareness of the ecological importance and conservation of earthworms. 

It was because earthworms were under-recorded and I was fascinated by them that I decided to join the Earthworm Society of Britain (ESB) to inspire others to better understand them and their habitats. I learnt more about the society after volunteering to charm worms at The Natural History Museum in 2010. I was later inspired by several talks about the lives of earthworms by the spritely, enthusiastic Emma Sherlock who is chair of the society and earthworm curator at the museum.

The ESB is a voluntary organization that plays an important part in supporting scientific research to improve the conservation of earthworms and their habitats and educates and inspires people to take action to help earthworms. The ESB runs the National Earthworm Recording Scheme and training courses and events for those who are keen to identify and record earthworms.

Passionate people like Keiron Derek Brown, Earthworm Recording Officer for the Society ensures they have a voice in the biological recording community and wider biodiversity sector. If you would like to find out more about earthworms and how to get involved in recording earthworms near you, then visit the ESB website or perhaps attend a future ‘learn to love earthworms’ course being delivered in partnership with the Field Studies Council.

My role at the Earthworm Society of Britain is to answer enquiries from our members, individuals, researchers, wildlife organisations and many other people who are interested in earthworms. Enquiries could include requests for identification of earthworms and other similar invertebrates, confirming records that have been submitted, requests for data or requests by organisations to offer advice or talks around earthworm species, their distribution and conservation. If you would like to learn more about and help conserve earthworms and their habitats, then join the Society.

Earthworm Identification

Earlier this month, I refreshed my earthworm identification skills by attending an identification course delivered by Emma Sherlock that coincided with the launch of her new AIDGAP key to the Earthworms of Great Britain and Ireland at the Angela Marmont Centre for UK Biodiversity (AMC). The AMC is a centre for excellence in the study of UK Biodiversity, it supports individuals, schemes and societies that record, monitor and protect the UK's biodiversity and is home to the UK Species Inventory. It is also where I myself trained as an Identification Trainer for the Future. The course began with an introduction to the earthworm ecotypes of surface (Epigeic), soil (Endogeic) and deep-living (Anecic) earthworms. Each ecotype is based on the earthworm’s behaviour and where they like to live and feed in the soil.

Earthworms do not all live in the same places in the soil but through their burrowing and eating actions they change the structure of the soil and allow nutrients to be changed into a form that plants can take into their roots. Epigeic earthworms live at or near the soil surface in leaf litter. These species do not make burrows but live in and consume and digest dead plants instead of the soil. They are often bright red or reddy-brown.

Endogeic earthworms as the name suggests live in and feed on the soil. They make horizontal burrows through the soil to move around and to feed and they will reuse burrows. They are often pale in colour - grey, pink, green or blue. Finally, deep-living earthworms make permanent vertical burrows in soil. They feed on leaves on the soil surface that they drag these into their burrows. They also make ‘casts’ on the surface, and these casts can quite often be seen in grasslands. They also make ‘middens’ (piles of vegetation and stones) around the entrance to their burrows.

Anecic earthworms such as Lumbricus terrestris are the largest and deepest living of the earthworms in the UK. They are darkly coloured at the head end (red or brown) and have paler, sometimes flattened tails.

Following an introduction to their ecology, we went to Kensington Gardens to undertake earthworm sampling and learn more about the field identification and collection, including how to preserve specimens. We found a lot of Epigeic and Endogeic earthworms in our first sampling efforts which involved searching through leaf litter and digging shallow pits underneath leaf litter. These methods are outlined in the ESB’s Recorder Handbook and a collection technique used for sampling anecic earthworms is mixing mustard powder with water to make a vermifuge which is poured over an area that you wish to sample. This then encourages any earthworms to the surface which can then be sampled to ensure earthworm burrows and other habitats are not damaged by digging too deeply.

Lab identification

Once we had collected enough specimens, we headed back to the AMC to undertake lab identification using a microscope and the new AIDGAP key. To successfully identify earthworms to species level one has to confirm the shape of the head and count the number of segments down to the clitellum (also known as the saddle). The clitellum is a thickened band which is developed in adult earthworms and means they can reproduce. One also has to identify on which segment the clitellum starts and finishes, where the Tubercula Pubertatis (or TP) starts and finishes (its shape also can vary greatly from species to species), which segments the male pore is located on (this is also for earthworm reproduction and is where sperm is released) and whether the hairs (setae) which run down the length of the earthworm’s body are closely or widely spaced. It takes practice but by identifying these key characters with a microscope one is able to accurately confirm the species which wouldn’t otherwise be possible with just an image, unlike some other species groups.

I was delighted to identify a variety of surface, soil and deep-living earthworms effectively without support using the key. I also discovered that I had successfully identified Satchellius mammalis at our leaf litter site in Kensington Gardens which is a much less common earthworm. The leaf litter survey was conducted in area surrounded by trees and S  mammalis’ favoured habitat is woodland, areas of high organic matter and river banks. It was a really interesting day and I would like to thank Emma Sherlock and the team at the AMC for supporting the training.