Catching the worm

Catching the worm

Catching the worm - UK and Ireland : •Lead photo: NT •Carousel image credits: NT, moremoth, HB, Lloyd9632, JulieK1967, dejayM, NT, NT

•Lead photo: NT

•Carousel image credits: NT, moremoth, HB, Lloyd9632, JulieK1967, dejayM, NT, NT

We all know that worms are important, right?

Charles Darwin put the spotlight on earthworms in his book The Formation of Vegetable Mould Through the Action of Worms way back in 1881! Despite earthworms being generally easy to recognise, according to Emma Sherlock, Chair of the Earthworm Society of Britain (ESB), they are some of the least recorded organisms. We have 31 species (some very rare) in the UK and Ireland, all but two being in the Lumbricidae family. Sherlock (2018) says that more needs to be known about their habitat preferences and so more observations are needed in many more parts of the country.
Ref: Sherlock, E. (2018) Key to the earthworms of Britain and Ireland. FSC.

The ESB course for would-be recorders involves dissection as this is required for accuracy. However, iSpot DOES NOT expect anyone to attempt dissection when the experts have already done this for us! Better is for everyone who can to go out, find a worm and take several photos. After that, make the best possible identification by checking the ID features using the keys available online before finally recording the observation.
iSpot's own earthworm key is very helpful: https://www.ispotnature.org/webkeys/keyintroduction.jsp?selectedKey=webkeys/easy-worms.0.5 It's based on the OPAL Soil and Earthworm Survey field key, produced to identify a small number of common LIVE specimens, and a downloadable id chart can be accessed via this page: https://www.imperial.ac.uk/opal/surveys/soilsurvey/ However, as long as we recognise the limitations to the OPAL key, we shouldn't be deterred from looking for worms to id. See this ESB page: https://www.earthwormsoc.org.uk/OPALkey

Where to look? There are 4 ecotypes:

1. Anecics make permanent vertical burrows; they feed on leaves from the surface by dragging them into their burrows; some soil can be ingested; they cast on the surface; they are deep red dorsally and always large. The Lob worm is an example. See NT's https://www.ispotnature.org/communities/uk-and-ireland/view/observation/821979/

2. Endogeics live in and feed on the soil; they are often pale colours, grey, pale pink, green or blue. They are found at different depths, varying by species, life stage and seasons. It's most likely to be the endogeics we see on pavements following rain. Moremoth's Octolasion cyaneum Blue-grey worm is an example and this is often found at up to 15cm of the soil surface (https://www.ispotnature.org/communities/uk-and-ireland/view/observation/570283/), whereas others are commonly found at about 8cm depth. HB's Allolobophora chlorotica Green worm (https://www.ispotnature.org/communities/uk-and-ireland/view/observation/676233/) prefers wetter conditions compared to the pink form.

3. Epigeics usually live on the surface of soil in leaf litter or under logs, bark and dung; they are bright red or reddy-brown. Dendrobaena veneta (previously Eisenia veneta) is also used in vermicomposting and has a stripy appearance when stretched. Epigeics tend to be smaller in size. Some examples are: Lloyd9632 at https://www.ispotnature.org/communities/uk-and-ireland/view/observation/774826/, JulieK1967 at https://www.ispotnature.org/communities/uk-and-ireland/view/observation/166905/ and
dejayM at https://www.ispotnature.org/communities/uk-and-ireland/view/observation/587128/

4. Composters are a sub-group of the epigeics, known commonly as the tiger or brandling worm; they live in compost bins/heaps or areas very rich in rotting vegetation and are bright red and stripy. They are often longer than the other epigeics. An example is at https://www.ispotnature.org/communities/uk-and-ireland/view/observation/822973/

All the above information is beautifully illustrated here: https://www.earthwormsoc.org.uk/earthworm-ecology and knowing the habitat should help with the process of identification.

Tips for earthworm ids and finding them:

As with many organisms, identification isn't easy - a comment iSpotters will understand!
•Earthworms without a saddle are juveniles and cannot be identified. The position of the saddle is a key feature in identification, which is why we can only attempt to identify adult worms. See https://www.ispotnature.org/communities/uk-and-ireland/view/observation/825140/
•Some species have 2 or more colour morphs - try more than one key.
•Some worms will put on a spurt and make photography tricky, making the id even more difficult! If possible, rinse the worm in clean water to remove soil before photographing it. This helps later if you want to try and count the segments.
•Besides in the soil, there are other microhabitats where earthworms can be found such as under plant pots or bin bags (regardless of the surface they are on); a check under logs and other objects resting on soil can turn up anecic, endogeic and epigeic earthworms. Use this technique if the area under the item is damp.
•This is a 5-minute BBC clip to get you going in the garden: https://www.bbc.co.uk/programmes/p06nx5j5
•Search under deadwood and also check for earthworms under the bark and within the deadwood, while ensuring minimal damage to the microhabitat.
•Dung may yield earthworms within or beneath it.
•Leaf litter can be searched for earthworms.
•Compost heaps/bins should be home to dense earthworm populations.
•And last but not least, they will be easier to find in or out of the soil when it's damp or even raining!

How safe is our earthworm population?

There are dangers to earthworms through some agricultural practices, climate change,and predation. The native wildlife won't decimate the earthworms but some iSpotters are already very aware of the non-native flatworms destroying the native populations. See: https://www.earthwormsoc.org.uk/PotWatch
They can be recorded here: http://www.nonnativespecies.org/home/index.cfm
Here are a couple of iSpot examples:
Thistle's at https://www.ispotnature.org/communities/uk-and-ireland/view/observation/819854/ and
markwilson's at https://www.ispotnature.org/communities/uk-and-ireland/view/observation/822485/

The UK is not the only country with invasive species. For example, there are no earthworms native to the Great Lakes; read this and watch the video at the bottom right of the page: http://nrri.umn.edu/WORMS/default.htm

02 Jul 2021
NorthernTeacher