Leeches are instantly recognisable freshwater animals. The clear segmentation and presence of suckers at each end ensure that there are few other organisms with which they may be confused, although leeches attract a mixed response from those that encounter them. However, the authors hope that readers will come to recognise that leeches are 'worms of character', and probably represent the peak of annelid evolution. Leeches are sinuously elegant swimmers, and are often beautifully coloured. They have a compact, muscular body, and a well-developed nervous system with efficient sense organs. Therefore, they are very efficient at locating their prey, and are ideal subjects for the future study of predator-prey relationships both in the laboratory and the field. As leeches are hermaphrodites, there are no problems in having to separate the sexes, making them ideal subjects for the future study of their population dynamics.
Freshwater Leeches of Britain and Ireland is the fourth FBA Scientific Publication to provide an identification key to freshwater leeches, the most recent edition appearing in 1979. In this new version the nomenclature has been revised and the keys to species re-organised into a more logical progression. All the illustrations accompanying the keys are new and have been drawn by Mike Dobson. The ecology section, which has proved so useful in the previous edition, has been enlarged with the addition of over 200 references. The taxonomy of leeches in Europe is in a period of major change and invasive species, among leeches as with so many other organisms, are encroaching upon freshwater habitats across the continent, so these notes include comments on species that might be expected to appear in new locations in the coming years.
Check List 11
Non-Native Species 13
Collection, examination and preservation 17
Notes on the use of the Key 18
Key to Families 21
Key to Species 23
A Key to two Species of Piscicolidae 23
A Key to eight Species of Glossiphoniidae 26
A Key to two Species of Haemopidae and Hirudinidae 31
A Key to five Species of Erpobdellidae 33
Leech cocoons and their Identification 36
Life cycles and ecology 38
General aspects 38
Family Piscicolidae 44
Family Glossiphoniidae 46
Family Haemopidae 60
Family Hirudinidae 62
Family Erpobdellidae 72
Conclusions and future directions 82
Overall this is a useful and important booklet and I have only one major comment, about a feature which this shares with so many other field keys. Although the paper is slightly glossy, it is not really sufficiently tough for use in field conditions and the 'perfect binding' is guaranteed to fail eventually, as the booklet is opened forcibly in field conditions. I wish that field keys were prepared so as to be used freely in the field. Surely this is how it should be! Nevertheless, I thoroughly recommend this."
– Mark Young, BES Bulletin 46(4), December 2015