Oniscus asellus

Oniscus asellus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Isopoda
Family:	Oniscidae
Genus:	Oniscus
Species:	O. asellus
Binomial name
Oniscus asellus Linnaeus, 1758
Synonyms [1]
Oniscus affinis Oniscus fossor Oniscus lamperti Oniscus languidus Oniscus lineatus Oniscus murarius Oniscus nodulosus Oniscus taeniola Oniscus vicarius Porcellio lineatus Porcellio taeniola

Oniscus asellus, the common woodlouse, is one of the largest and most common species of woodlouse in the British Isles and Western and Northern Europe, growing to lengths of 16 mm and widths of 6 mm.

Distribution

Oniscus asellus is the most widespread species of woodlouse in the British Isles, both geographically and ecologically.^[2] It is not known from the Mediterranean Basin, but is widespread in Northern and Western Europe, as far east as the Ukraine, as well as in the Azores and Madeira; it has also been widely introduced in the Americas.^[1]

Ecology

Oniscus asellus occurs in a wide range of habitats, including some with little available calcium. It is chiefly found under stones, and on rotting wood.^[2] It is the only woodlouse regularly found on heather moors and blanket bogs, where it lives around items such as rotting fenceposts.^[2]

Description

Oniscus asellus is one of the largest native woodlice in Britain, at up to 16 mm (0.63 in) long.^[3] It is relatively flat, and is a shiny grey in colour,^[2] although juveniles are rougher.^[3]

Pale patches are often visible on the back of Oniscus asellus; these are areas that store calcium, which is then used to reinforce the exoskeleton after a moult.^[3] Moulting occurs in two halves, with the rear half moulting before the front half. The exuvia is often consumed by the animal after moulting.^[3]

See also

• List of woodlice of the British Isles

References

1. ^ ^{a b} Helmut Schmalfuss (2003). "World catalog of terrestrial isopods (Isopoda: Oniscidea) – revised and updated version". Stuttgarter Beiträge zur Naturkunde, Serie A 654: 341 pp. http://www.oniscidea-catalog.naturkundemuseum-bw.de/Cat_terr_isop.pdf. 
2. ^ ^{a b c d} Paul T. Harding & Stephen L. Sutton (1985) (PDF). Woodlice in Britain and Ireland: distribution and habitat. Abbots Ripton, Huntingdon, Institute of Terrestrial Ecology. pp. 151. ISBN 0904282856. http://nora.nerc.ac.uk/5276/1/Woodlice.pdf.  accessed through the NERC Open Access Research Archive (NORA)
3. ^ ^{a b c d} "Common woodlouse (Oniscus asellus)". ARKive.org. http://www.arkive.org/common-woodlouse/oniscus-asellus/info.html. Retrieved February 22, 2009.