Earthworm identification

How do I identify earthworms?

A vital part of recording earthworms is to know how to tell each species from another. Earthworms have a number of characters that allow us to tell the difference between the species. As earthworms in general are not very large, some of these characters are require a microscope to investigate the characters in detail, but if you don't have a microscope a strong hand lens can work ok on larger species. An identification key can then be used to determine which species an earthworm is based on the characters that are present. The picture below, taken from Key to the Earthworms of the UK & Ireland by Sherlock (2012), shows some of the main characters that are used in identifying earthworms.

Earthworm anatomy

Identification Keys

AIDGAP EarthwormsKey to the Earthworms of the UK & Ireland by Sherlock (2nd edition) (2018)
Produced by the Field studies Council as part of their AIDGAP series. The second edition expands on the ecology and biology sections of the first edition, and briefly summarises the global picture. The dichotomous key has been updated with current taxonomic names and includes 2 additional species now known to occur in the British Isles. the species pages have also been expaneded to include more information and photos, including some photos of live earthworms. Finally, a guide to identifying 8 of the non-native earthworm species that are found in artificial environments, such as heated glasshouses, is also included.

Sherlock's FSC AIDGAP KeyKey to the Earthworms of the UK & Ireland by Sherlock (1st edition) (2012)
Produced by the Field Studies Council as part of the AIDGAP series. This key provides a basic background in earthworm biology and ecology, as well as information on sampling, recording and preserving earthworms. In addition to a dichotomous key, there is a quick earthworm comparison chart and species accounts. This resource is still suitable for identifying British and Irish earthworms but does have some limitations as some species names have changed since this publication, 1 species has been split into 2 species and our ecological understanding of some earthworm species has since been updated. THIS PUBLICATION IS NOW OUT OF PRINT.

Sims and GerardEarthworms by Sims & Gerard (1999) 
This publication is part of the Synopses of the British Fauna and provides a much more detailed account of UK earthworm biology and taxonomy. The technical detail contained within the dichotomous key and diagrams make this key suitable for more experienced users. It is also available from the FSC. This resource is still suitable for identifying British and Irish earthworms but does have some limitations as some species names have changed since this publication, 1 species has been split into 2 species and our ecological understanding of some earthworm species has since been updated.

Earthworm Identikit
The FSC Tomorrow's Biodiversity project have created an online multi-access key based on the content of the FSC AIDGAP key (the printed key is often still required to verify identification). This tool can be particularly useful when all features on an earthworm can not be seen (for instance if the specimen is damaged or identifying from a photograph). However, please note that the tool does not currently take into consideration the shape of the TP and one of the above identification resources may still be required to reach a species determination.

OPAL Earthworm Guide
This key to the common species of UK earthworms only and covers less than half of UK earthworm species. It is not a sufficiently detailed identification key for the purpose of the National Earthworm Recording Scheme. Few British species can be reliably identified from live specimens in the field. 

Identification Workshops

The Earthworm Society of Britain (ESB) runs earthworm identification workshops where you can learn how to identify British earthworms. These are suitable for anyone interested in learning how to identify earthworms using a microscope and identification key. You can find out more about more about this on our Earthworm Identification Training webpage. Please check out our upcoming events and our Facebook Page for more details.