''Porcellio laevis'' ( commonly called the swift woodlouse, or smooth slater in

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

) is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

woodlouse Woodlice are terrestrial isopods in the suborder Oniscidea. Their name is derived from being often found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects. Woodlice evolved from marine isopods ...

in the genus '' Porcellio''. As the species epithet ''laevis'' as well as the vernacular name "swift woodlouse" suggests, the species is capable of quick bursts of speed when provoked. This species of woodlouse is distinctively large, appearing up to long with a smooth dorsal surface. The males can be identified by their long, spear-shaped

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

s. The smooth dorsal surface of ''Porcellio laevis'' separates it visually from many other species in the same genus. It is commonly kept as a pet due to its somewhat easy care requirements and the variety of color morphs available. The species is easy to keep and can be easily established in a terrarium within a few weeks. "Dairy cow isopod" is a commonly used name for a readily available piebald strain of the species.

Distribution and habitat

''P. laevis'' was first recorded in Britain in the 13th century but it likely originated in North

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. It has a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

, and has been introduced to

, including

Norfolk Island Norfolk Island ( , ; ) is an States and territories of Australia, external territory of Australia located in the Pacific Ocean between New Zealand and New Caledonia, directly east of Australia's Evans Head, New South Wales, Evans Head and a ...

and

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland Port ...

. The species is also found in North and South America, Western Asia, Japan and some Pacific islands. This species is found under rocks and fallen logs in damp areas, and is otherwise rarely encountered. Records from Ireland and Britain also place them in agricultural areas like gardens, farms, and stables where they can be found in dung and compost piles.

Development and maternal care

''Porcellio laevis'' directly develop from yolky eggs. Both the eggs and juveniles develop within a brood pouch called a marsupium until the first juvenile stage. The use of the marsupium eliminates the need for there to be an external water source for early development since it is filled with fluid from the mother isopod. This is considered some of the most extensive parental care among terrestrial arthropods.

Ecological significance

''Porcellio laevis'' plays an important role in

nutrient cycling A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyc ...

in habitats by breaking down dead plant material and animal waste, and thereby releasing essential nutrients back into the ecosystem. The species is known to be an opportunistic feeder, consuming a wide range of organic matter such as leaves, moss, lichens, and even rotting wood. Therefore, ''P. laevis'' can thrive in many different ecological niches. It is also an important food source for many animals, including birds, reptiles, and small mammals. ''P. laevis'' have the ability to tolerate and even accumulate heavy metals in their bodies, making the potentially useful in the

bioremediation Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi in mycoremediation, and plants in phytoremediation), living or dead, is employed for removing environmental pollutants from air, wate ...

of heavy metal-contaminated soils.

Behavior

''Porcellio laevis'' is one of several species of

isopods Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as woodlice. All have rigid, segmented exoskeletons ...

known to use "alternating turns" as a defense mechanism, running in a mazelike pattern to confuse or avoid perceived threats. Studies suggest that this behavior, also observed in ''

Armadillidium vulgare ''Armadillidium vulgare'', the common pill-bug, common pill woodlouse, roly-poly, slater, doodle bug, or carpenter, is a widespread European species of woodlouse. It is the most extensively investigated terrestrial isopod species. It is native t ...

'', can be reinforced as a learned response, with more "alternating turns" produced by longer and more frequent exposure to predators.

Polymorphism

''Porcellio laevis'' is known to exhibit polymorphism. Multiple polymorphic traits have been line-bred or isolated to produce colonies of ''Porcellio laevis'' that can vary widely in color and pattern (sometimes referred to informally as "morphs").

References