Woodlice
| Woodlouse | |
|---|---|
 |
|
| Porcellio scaber (left) and Oniscus asellus (centre) living on fallen wood | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Order: | Isopoda |
| Clade: | Scutocoxifera |
| Suborder: |
Oniscidea Latreille, 1802 |
| Infraorders and sections | |
A woodlouse (plural woodlice) is an isopod crustacean with a rigid, segmented, long exoskeleton and fourteen jointed limbs. Mostly they feed on dead plant material, and they are usually active at night. Woodlice form the suborder Oniscidea within the order Isopoda, with over 5,000 known species.
Woodlice in the genus Armadillidium and in the family Armadillidae can roll up into an almost perfect sphere as a defensive mechanism, hence some of the common names such as pill bug or roly-poly. Most woodlice, however, cannot do this.
Common names for woodlice vary throughout the English-speaking world. A number of common names make reference to the fact that some species of woodlice can roll up into a ball. Other names compare the woodlouse to a pig.
Names include:
The woodlouse has a shell-like exoskeleton, which it must progressively shed as it grows. The moult takes place in two stages; the back half is lost first, followed two or three days later by the front. This method of moulting is different from that of most arthropods, which shed their cuticle in a single process.
A female woodlouse will keep fertilised eggs in a marsupium on the underside of her body until they hatch into offspring that look like small white woodlice curled up in balls. The mother then appears to "give birth" to her offspring. Females are also capable of reproducing asexually.
Despite being crustaceans like lobsters or crabs, woodlice are said to have an unpleasant taste similar to "strong urine".
Pillbugs (woodlice of the family Armadillidiidae, also known as pill woodlice) can be confused with pill millipedes of the order Glomerida. Both of these groups of terrestrial segmented arthropods are about the same size. They live in very similar habitats, and they can both roll up into a ball. Pill millipedes and pillbugs appear superficially similar to the naked eye. This is an example of convergent evolution.
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Wikipedia