With the return of wintry weather there’s little chance of finding many flying insects at the moment so - when not pruning or planting up hedge gaps in the Wildlife Garden - we’ve been focusing on animals found at ground level under stones, logs, leaf litter and within pitfall traps (n.b. more about pitfall traps another time). Amongst these animals, woodlice are a rewarding group to study as some of us learnt at a Woodlouse Workshop we attended a week ago last Sunday.
The study day, held in the Angela Marmont Centre for UK Biodiversity, was led by Museum scientists Miranda Lowe and Duncan Sivell and covered an introduction to woodlouse anatomy and classification, as well as ecology and recording methods. Below are just a few of the many interesting facts we learnt:
Woodlice are crustaceans and are related to crabs, lobsters and shrimps. They belong to a group called Isopoda which means ‘equal legs’. Most Isopoda are marine animals but woodlice are one of the few groups of crustaceans that have adapted successfully to life on land. They live in damp dark places, beneath logs, stones or leaf litter, where they feed on rotting wood and other decaying vegetable matter, helping to recycle nutrients back into the soil.
Miranda described their basic anatomy, general body form, and some of the diagnostic features that help to distinguish between the different species. Woodlice have an oval flattened body which will vary in colour and form depending on the species, and seven pairs of legs (pereopods).
Common striped woodlouse, Philoscia muscorum - their colour can vary but all have a dark head and dark stripe along their back
© Martin Angel
The general body form of the different genuses explains some of their behaviour – there are six types: runner, clinger, roller, creeper, spiny form and non-conformist, of which the first four only are found in Britain. When you pick up a woodlouse, you may recognise it by its body form - for example, if disturbed, the common pill woodlouse, Armadillidium vulgare, will roll into a ball. Conversely, a common striped woodlouse, Philoscia muscorum, is a definite runner ...
Common pill woodlouse, Armadillidium vulgare
© Martin Angel
Apart from body form, shape and colour, another useful diagnostic feature is the antennae and it is important to examine the individual sections. For example, the common rough woodlouse, Porcello scaber, has a flagellum (end section of an antennae) made up of 2 segments whereas the common striped woodlouse has a 3-segmented flagellum. We were equipped with microscopes to observe these finer details.
Common rough woodlouse, Porcellio scaber
© Martin Angel
These woodlice are three of the five species most commonly found in gardens - together with the other two species, they are known as the ‘Famous Five’. The remaining two in this club are common pigmy woodlouse, Trichoniscus pusillus, and the common shiny woodlouse, Oniscus asellus.
Common shiny woodlouse, Oniscus asellus
© Harry Taylor, Natural History Museum
The different body form and characters may explain many of the affectionate, common names that woodlice have acquired throughout the ages and in different parts of the country. Duncan introduced us to some of these names such as slater where he comes from in the north, bibble-bug, cheese-pig, roly-poly and chuggy pig. The authors of Bugs Britannica discovered 80 nicknames for woodlice!
Duncan also told us more about the favourite habitats of woodlice and how to collect and record the different species. We explored the dark and damp underside of logs, leaf litter and compost bins in the Wildlife Garden and returned to the lab to identify our collection.
Common shiny woodlouse at home
© Derek Adams, Natural History Museum
In our brief foray in the bitter wind, we found 5 different species - four of the Famous Five and Porcellio dilatatus. We know there are at least seven different species in the garden in addition to the honourary woodlouse, the landhopper, Arcitralitrus dorrieni.
But this is just a taster of the some of the fascinating facts and details we learnt about these endearing little animals. At a later date Miranda will write about the landhopper which has made itself at home in the Wildlife Garden.
Thank you Miranda and Duncan