These woodlice have long antennae with setae, which sense movement, and shorter antennae which may function as chemoreceptors. They also sense their environments through touch, as evidenced by their thigmokinetic behavior, which causes reduced movement when in physical contact with other objects. Common rough woodlice may use pheromones, either released by feces or produced separately, to find others of their species in order to create aggregations. They have two compound eyes that can sense light and dark.
Communication Channels: visual ; tactile ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; chemical
The conservation status of common rough woodlice has not been evaluated.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
This species undergoes direct development with 15-20 recognized stages, beginning with fertilization. These stages occur through a series of molts and are differentiated by morphological changes or development of organs. Eggs are carried in the female's fluid-filled brood pouch where they hatch; after hatching, they are referred to as mancae. There are two manca stages that take place within the pouch and two that occur outside of the pouch. Mancae are soft, white, and have only six pairs of legs; the seventh pair develops after their first molt. The development of the seventh pair of legs occurs outside of the pouch and, after this, the mancae are considered juveniles. Juveniles are similar in appearance to adult wood like.
In some regions where it has been introduced, this species has had a negative impact on the niches of the native flora and fauna. These animals eat decaying matter, releasing nutrients into the soil, but this may not be ideal in regions that have developed without detritivores present. In regions that have, they may compete with native detritivore species.
Negative Impacts: crop pest
Common rough woodlice are decomposers of wood and other organic matter, releasing minerals, nutrients and other chemicals into their environments. They are also useful as model organisms in many scientific studies and have been used to test contamination levels of heavy metals such as cadmium, lead and zinc in soil.
Positive Impacts: research and education
Common rough woodlice are detritivores that help with the degradation of organic matter, such as decaying leaves and wood. In its native regions, this works to quickly return nutrients to the soil. In some areas with a slower degradation process, introduced woodlice significantly affect indigenous flora and fauna.
Melanophora roralis are parasitic flies that lay eggs on common rough woodlice, killing their hosts during their pupation. Other parasites include spiny headed worms and nematodes. Common rough woodlice also host intracellular parasitic bacteria in their guts.
Woodlice are susceptible to Iridovirus (IIV) Type 31, which creates crystalline structures in the host's tissues, lending them a blue color, and leading to death in extreme infections. This species may also become infected by Wolbachia, a bacteria that affects hormone production in males.
Common rough woodlice also have endosymbiotic bacteria that help them to digest plant matter living in their hepatopancreas.
Ecosystem Impact: biodegradation
Mutualist Species:
Commensal/Parasitic Species:
Common rough woodlice are detritivorous, saprophagous (including carrion), mycophagous, and coprophagous. They prefer decaying organic matter because of the higher population of microbes within this material. Common rough woodlice consume their own feces in order to increase copper stores (necessary as their blood contains haemocyanin) and to retain bacteria that are able to break down nutrients that are not easily absorbed otherwise. These bacteria are a significant part of their diets. These woodlice also have endosymbiotic bacteria (Candidatus Rhabdochlamydia porcellionis) living in the hepatopancreas, which help with cellulose digestion.
Animal Foods: carrion
Plant Foods: leaves; roots and tubers; wood, bark, or stems; fruit
Other Foods: fungus; detritus ; dung; microbes
Primary Diet: carnivore (Scavenger ); herbivore (Folivore , Frugivore ); omnivore ; mycophage ; detritivore ; coprophage
Common rough woodlice are considered native to mainland Europe. This species has spread throughout the world, including onto isolated islands such as Hawaii and Marion Island (located between Africa and Antarctica) and is found on every continent, not including Antarctica. Their dispersal has been facilitated by humans, as they can easily be transported via leaf matter and wood. They prefer temperate climates.
Biogeographic Regions: nearctic (Introduced ); palearctic (Native ); oriental (Introduced ); ethiopian (Introduced ); neotropical (Introduced ); australian (Introduced ); oceanic islands (Introduced )
Other Geographic Terms: cosmopolitan
Because they do not have a waxy cuticle covering their exoskeletons, common rough woodlice prefer moist, dark areas where it is possible to avoid dessication. They live under leaf litter, rocks, and fallen logs in forests, meadows, and gardens, and are frequently found in splash zones, dunes and salt marshes. Although they are most often found in leaf litter, they are often found on tree bark as well, particularly during the summer.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; forest
Wetlands: marsh
Other Habitat Features: urban ; agricultural
Although there is little information regarding lifespan for common rough woodlice specifically, terrestrial isopods live between 1-5 years on average. It has been suggested that this species typically lives 2-3 years, though up to 90% die within a month of emerging from their brooding pouches.
Typical lifespan
Status: wild: 1 to 30 months.
Common rough woodlice are ectothermic and have flat, elliptical-shaped bodies that are heavily plated and typically grey or deep blue, though orange and albino specimens have also been seen. They can grow up to 17 mm in length and, like other arthropods, their bodies are segmented and bilaterally symmetrical. They have seven body segements, each with a pair of legs, and their bodies are divided into three sections: head, pereion (thorax), and pleon (abdomen), and their heads are divided into three lobes. Their two pleopodia (appendages under their pleons), have pseudotrachia, allowing for respiration through their pseudolungs. These pseudolungs appear as white patches on the abdomen, and they are unable to be closed to prevent water loss. Weight varies depending on water content, which can fluctuate greatly. These isopods have a warty body surface with two short tails (uropodia) on their final body segments (telsons). They have compound eyes and two pairs of antennae, a shorter pair which are thought to act as chemoreceptors and a longer pair which have sensory hair-like structures (setae). The antennae are often orange in color at their bases. Common rough woodlice can not roll into a ball for defense as many closely related species can. This species is sexually dimorphic, with females (and juveniles) mottled and lighter in color. Females have a brood pouch in which they carry developing young, while males have a genital projection located near their pleopodia.
Average length: 17 mm.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently
These woodlice protect themselves from predation by hiding under wood, rocks, leaves and other detritus. Their bodies are also heavily plated. They also excrete nitrogenous waste in the form of ammonia gas instead of urine, which may help to ward off would-be predators. Nevertheless, common rough woodlice have a number of natural predators such as spiders (including Dysdera crocata, known as woodlouse hunters, which feed exclusively on them), small mammals (such as shrews), birds, centipedes, harvestmen, and ground beetles.
Known Predators:
Anti-predator Adaptations: cryptic
Common rough woodlice reproduce sexually, during warmer spring and summer seasons. Males insert sperm using their copulatory organ, a modification of their abdominal legs. This species is polyandrous; females mate with many males and broods have been shown to have greater than 80% multiple paternity.
Mating System: polyandrous
It is possible for common rough woodlice to have one to three broods per year, with 12-36 offspring per brood. Females may survive long enough to breed in multiple seasons, but often do not. Reproduction typically occurs when the days lengthen and temperatures rise during spring and summer, and females have been noted to be gravid for an average of 35 days. Males and females can can be distinguished by their sixth molt, and reach full sexual maturity within 14-22 months after hatching.
Breeding interval: This species may breed up to 3 times a year.
Breeding season: These isopods breed during the spring and summer.
Range number of offspring: 12 to 36.
Average number of offspring: 20.
Range age at sexual or reproductive maturity (female): 14 to 22 months.
Range age at sexual or reproductive maturity (male): 14 to 22 months.
Key Reproductive Features: semelparous ; seasonal breeding ; sexual ; fertilization (Internal ); ovoviviparous
Males exhibit no parental investment after mating. Females carry eggs and mancae in a fluid-filled breeding pouch in order to prevent their dessication. Once mancae have been released there is no further parental involvement.
Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Protecting: Female); pre-independence (Protecting: Female)
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.
One subspecies, Porcellio scaber lusitanus, is currently recognized. Two other subspecies were historically deemed valid but are no longer recognized. P. s. americanus, described in 1932,[2] was considered endemic the Americas. P. s. japonicus was described in 1928 and believed to be endemic to Japan.[3] Both subspecies were synonymized with the nominate in 2020.[4]
Porcellio scaber is found across Central and Western Europe.[5] 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.[6] It is also the most common species of woodlice found in Australia.[7]
Porcellio scaber has an oval body, can grow up to 20 millimetres (0.79 in) long, and is usually a grey colour, paler underneath, although, brown, blue, yellow, orange, or pinkish hues may also be observed. The dorsal (upper) surface of its segmented exoskeleton is covered in a series of small tubercles hence its common name.
At the head it has two pairs of antennae, with the inner pair being very small. Two compound eyes are located on the dorsal side of the head, while the mouthparts are on the ventral (lower) side.
There are 7 pairs of legs, corresponding to the 7 segments of the thorax. The short abdomen consists of 6 segments.[8] On the ventral side of the abdomen there are two whitish pseudo-lungs, connected with pores to the outside air. At the rear end there is a small telson flanked by a pair of appendages known as uropods.[8]
Porcellio 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.[9]
Porcellio 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.[10] P. scaber has very sensitive olfactory receptors that allow it detect the smell of microbial activity and to locate food.[11]
The females carry about 25 to 90 fertilized eggs until they hatch and are held in a fluid-filled sac at the ventral side of the abdomen for about 40-50 days. The young are reproductively mature after 3 months; the adult animals have a life expectancy of about two years.[8]
Porcellio 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 bilateral asymmetrical leg movement (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.[12]
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.[13]
Inspired by the behaviours of P. scaber, an algorithm for solving constrained optimization problems was proposed, called the Porcellio scaber algorithm (PSA).[14][15]
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.
