Porcellio scaber

Geographic Range

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. ("Isopoda", 2003; "Pocellio scaber (crustacean)", 2009; McGavin, 2000)

Habitat

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. ("Isopoda", 2003; Harding and Sutton, 1985; McKenzie, 1997)

Physical Description

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. ("Isopoda", 2003; "Pocellio scaber (crustacean)", 2009; Gunn, 1937; Harding and Sutton, 1985; Kaufman and Eaton, 2007; McGavin, 2000; Minor, 2011; "Common rough woodlouse", 2013)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Average length
    17 mm
    0.67 in

Development

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. ("Isopoda", 2003; Minor, 2011; Wolff, 2009; Zimmer, 2002)

Reproduction

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. ("Isopoda", 2003; Duffy and Thiel, 2007; Minor, 2011; Sassaman, 1978)

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. ("Isopoda", 2003; "Common rough woodlouse", 2013; Warburg, et al., 1984; Zimmer, 2002)

  • 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

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. ("Isopoda", 2003; Minor, 2011)

  • 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

Lifespan/Longevity

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. (McKenzie, 1997; Minor, 2011; Warburg, et al., 1984)

  • Typical lifespan
    Status: wild
    1 to 30 months

Behavior

Much of this species' behavior is related to its need for an appropriately humid environment; they will relocate based on whether they currently need more or less water in their systems. For example, in forest ecosystems, they have been observed in the upper parts of decidious trees during summer months and in mossy areas around the bases of trees during autumn months. These woodlice are most active at night and their activity levels are correlated with wind speed; increased wind speeds (and, so, evaporation rates) lead to lower levels of activity. They exhibit negative phototaxis, moving away from lighter (likely warmer and drier) conditions to darker ones, and they speed up their movements when environmental conditions are outside of an optimal range. Humidity and temperature also affect whether or not these animals burrow into leaf litter. This species exhibits thigmokinesis, which means that their movement is reduced when in contact with other objects. This includes other woodlice; aggregations can help to protect individuals from dessication and predation. ("Isopoda", 2003; Den Boer, 1962; Friedlander, 1964; Gunn, 1937; Hassal and Rushton, 1985; McGavin, 2000; McKenzie, 1997; Warburg, et al., 1984; Zimmer, et al., 2003)

Home Range

No published information on the home range of this species is available.

Communication and Perception

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. (Breithaupt and Thiel, 2011; Broly, et al., 2012; Friedlander, 1964; Minor, 2011; Nemanic, 1975)

Food Habits

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. ("Isopoda", 2003; "Pocellio scaber (crustacean)", 2009; Hassal and Rushton, 1985; Kostanjsek, et al., 2004; McGavin, 2000; McKenzie, 1997; Zimmer and Werner, 1998; Zimmer, 2002)

  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • fruit
  • Other Foods
  • fungus
  • detritus
  • dung
  • microbes

Predation

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. ("Isopoda", 2003; Carbines, et al., 1992; Hopkin, et al., 1986; McGavin, 2000; Minor, 2011; "Common rough woodlouse", 2013; Warburg, et al., 1984)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • Woodlouse hunter Dysdera crocata
    • Wolf spider (Lycosidae sp.)
    • Steatoda sp. (Family Theridiidae, Order Aranae)
    • Shrews
    • Birds
    • Centipedes
    • Harvestmen
    • Ground beetles

Ecosystem Roles

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. ("Pocellio scaber (crustacean)", 2009; McGavin, 2000; Minor, 2011)

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. (Beaudette, 1930; Hess and Poinar, Jr., 1985; Levri and Coppola, 2004; Sassaman and Garthwaite, 1984; Shay, et al., 1985; Zimmer, 2002)

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. (Cole and Morris, 1980; Cordaux, et al., 2001; Hess and Poinar, Jr., 1985; McKenzie, 1997)

Common rough woodlice also have endosymbiotic bacteria that help them to digest plant matter living in their hepatopancreas. (Kostanjsek, et al., 2004)

Mutualist Species
  • Candidatus Rhabdochlamydia porcellionis (Phylum Chlamydiae, Domain Bacteria)
Commensal/Parasitic Species
  • Melanophora roralis (Family Rhinophoridae, Order Diptera)
  • Plagiorhynchus cylindraceus (Class Palaeacanthocephala, Phylum Acanthocephala)
  • Chlamydia isopodii sp. (Phylum Chlamydiae, Domain Bacteria)
  • Capillaria annulata (Family Trichinellidae, Phylum Nematoda)
  • Thaumamermis cosgrovei (Family Mermithidae, Phylum Nematoda)
  • Wolbachia sp. (Family Rickettsiaceae, Phylum Proteobacteria)
  • Iridovirus (Family Iridoviridae)

Economic Importance for Humans: Positive

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. (Godet, et al., 2011; Kaufman and Eaton, 2007; Kostanjsek, et al., 2004)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

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. ("Isopoda", 2003; "Pocellio scaber (crustacean)", 2009)

  • Negative Impacts
  • crop pest

Conservation Status

The conservation status of common rough woodlice has not been evaluated. (IUCN, 2012)

Contributors

Cynthia Riggio (author), University of Michigan-Ann Arbor, Jeremy Wright (editor), University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

biodegradation

helps break down and decompose dead plants and/or animals

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

coprophage

an animal that mainly eats the dung of other animals

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

internal fertilization

fertilization takes place within the female's body

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

marsh

marshes are wetland areas often dominated by grasses and reeds.

motile

having the capacity to move from one place to another.

mycophage

an animal that mainly eats fungus

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

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ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

scavenger

an animal that mainly eats dead animals

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5? N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

References

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