Porcellio scaber (otherwise known as the common rough woodlouse or simply rough woodlouse), is a species of woodlouse native to Europe but with a cosmopolitan distribution. They are often found in large numbers in most regions, with many species (shrews, centipedes, toads, spiders and even some birds) preying on them.
P. scaber is found across Central and Western Europe. In the United Kingdom, it is one of the "big five" species of woodlice. It has also colonised North America, South Africa and other regions including the remote sub-Antarctic Marion island, largely through human activity. It is also the most common species of woodlice found in Australia.
P. scaber can grow up to 20 millimetres (0.79 in) long, and is usually a grey colour, paler underneath, although brown, blue, yellow, or pinkish hues may also be observed (like many other woodlice, a red variety can often be found in coastal areas). The dorsal surface of its segmented exoskeleton is covered in a series of tubercles hence its common name.
P. scaber loses water by diffusion through its permeable exoskeleton which lacks a waxy cuticle. Because of this, to avoid desiccation, it often seeks out environments with humid air and plenty of ground moisture, preferably cold to minimize rate of water loss, and dark to avoid detection by predators. It lives in a wide variety of damp habitats but it is less dependent on high levels of humidity than Oniscus asellus.
P. scaber is a detritivore - it mainly feeds on decaying leaf litter but will consume any rotting plant matter. Living plants are of limited nutritional value for these woodlice which prefer to feed on the bacteria and fungi which cause decay. P. scaber has very sensitive olfactory receptors that allow it detect the smell of microbial activity and so locate food. This ability to quickly detect the faintest sign of decay has led to the false belief that they harm seedlings and soft fruit.
P. scaber respond to certain stimuli with kinesis behaviour. To attempt to find an environment where they lose less moisture and then stay there, P. scaber alter factors such as speed and rate of turning (orthokinesis and klinokinesis). When in a dry or hot environment, these woodlice have been observed increasing speed and turn more often in an attempt to leave the unfavorable environment. In a moist, dark, cool environment, they slow down dramatically and often stop altogether. To avoid desiccation, most woodlice (including P. scaber) exhibit thigmokinesis, slowing down or stopping when in contact with multiple surfaces(such as the corner of a box or a crack between two bricks). This behaviour leads to clumping of woodlice, reducing the exposed surface area through which water can be lost. Another manifestation of this is that a woodlouse in a Petri dish is unwilling to move into the center of the dish, preferring to stay near the edge.
Another reflex exhibited by P. scaber is turn alternation. During klinokinesis, turns alternate between left and right. This helps the woodlouse escape from a harmful environment or predator more efficiently as alternating turns average to form a straight line, unlike random turns which may well become a circle back to the predator. Several mechanisms for this have been proposed, such as short-term memory or following the outside wall, but the theory with most support is the BALM mechanism, which suggests that on the original turn, the legs on the outside of the turn become relatively more tired, so end up being overpowered by the legs on the inside of the turn, causing it to turn the opposite way from last time.
Unlike the 'roller' species of woodlouse, such as Armadillidium spp., which are able to curl into a ball to defend themselves, P. scaber is a 'clinger' and adopts a posture of tonic immobility when faced with the threat of predation. A study of this thanatosis behaviour found that individuals of this species had unique personalities with shy woodlice staying still for longer and bold woodlice staying immobile for less time.
|Wikimedia Commons has media related to Porcellio scaber.|
- "Porcellio scaber". Integrated Taxonomic Information System.
- "Porcellio scaber". 2.6.1. Fauna Europaea. May 24, 2013. Retrieved May 25, 2013.
- Slabber, S.; Chown, S. "The first record of a terrestrial crustacean, Porcellio scaber (Isopoda, Porcellionidae), from sub-Antarctic Marion Island". Polar Biology. 25 (11). doi:10.1007/s00300-002-0420-9. ISSN 0722-4060.
- Sandra Hangartner; Garry McDonald (February 2015). "Slaters: Armadillidium vulgare & Porcellio scaber" (PDF). South Australian Research and Development Institute (SARDI). Archived from the original (PDF) on 2 August 2018. Retrieved 2 August 2018.
- "Porcellio scaber - a woodlouse". Natural England. Archived from the original on April 5, 2011. Retrieved January 19, 2009.
- Horvathova, Terezia; Babik, Wieslaw; Bauchinger, Ulf (2016-04-05). "Biofilm feeding: Microbial colonization of food promotes the growth of a detritivorous arthropod". ZooKeys. 577 (577): 25–41. doi:10.3897/zookeys.577.6149. ISSN 1313-2970. PMC . PMID 27110187.
- Zimmer, Martin; Kautz, G; Topp, W (1996-01-01). "Olfaction in terrestrial isopods (Crustacea: Oniscidea): Responses of Porcellio scaber to the odour of litter". European Journal of Soil Biology. 32: 141–147.
- Hughes, R. N. (1985-09-01). "Mechanisms for turn alternation in woodlice (Porcellio scaber): The role of bilaterally asymmetrical leg movements". Animal Learning & Behavior. 13 (3): 253–260. doi:10.3758/BF03200018. ISSN 0090-4996.
- Tuf, Ivan Hadrián; Drábková, Lucie; Šipoš, Jan (2015-07-30). "Personality affects defensive behaviour of Porcellio scaber (Isopoda, Oniscidea)". ZooKeys. 515 (515): 159–171. doi:10.3897/zookeys.515.9429. ISSN 1313-2970. PMC . PMID 26261447.
- Zhang, Yinyan; Li, Shuai (2017-09-28). "PSA: A novel optimization algorithm based on survival rules of porcellio scaber". arXiv: [cs.NE].
- Zhang, Yinyan; Li, Shuai; Guo, Hongliang (2017). "Porcellio scaber algorithm (PSA) for solving constrained optimization problems". MATEC Web of Conferences. 139: 00033. doi:10.1051/matecconf/201713900033. ISSN 2261-236X.