Woodlouse

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. The collective noun is reported to be a quabble (of woodlice). Common names include: • armadillo bug • boat-builder (Newfoundland, Canada) • butcher boy or butchy boy (Australia, mostly around Melbourne) • carpenter or cafner (Newfoundland and Labrador, Canada) • cheeselog (Reading, England) • cheesy bobs (Guildford, England) • cheesy bug (North West Kent, Gravesend, England) • chisel pig • chucky pig (Devon, Gloucestershire, Herefordshire, England) • chuggy pig (Devon, England) • doodlebug • fat pig (Ireland) • gramersow (Cornwall, England) • hobbling Andrew (Surrey) • hog-louse • (), (), granny grey in Wales • roll up bug • roly-poly • sow bug • wood pig (mochyn coed, Welsh) == Taxonomy ==

While the broader phylogeny of the Oniscideans has not been settled, eleven infraorders/sections are agreed on with 3,937 species validated in scientific literature in 2004 and 3,710 species in 2014 out of an estimated total of 5,000–7,000 species extant worldwide. The earliest onsicid fossils are from mid-Cretaceous. The most recent isopod phylogeny based on 148 isopods across 12 genes support the monophyly of the Oniscidea clade and a single terrestrialisation event . Movement further inland by Ligia or Tylos-like ancestors is likely to have occurred multiple times independently Two main schemes for the classification that differ in which group is considered sister to the remaining oniscideans. One places Ligiidae in section Diplocheta, with the remaining families divided between four sections in infraorder Holoverticata. The other places Tylidae in infraorder Tylomorpha, with the remaining families placed in three sections in infraorder Ligiamorpha. The former scheme is presented below. • Infraorder/section Diplocheta • Ligiidae • Infraorder Holoverticata • Section: Tylida • Tylidae • Section: Microcheta • Mesoniscidae • Section: Synocheta • Schoebliidae • Styloniscidae • Titaniidae • Trichoniscidae • Turanoniscidae Section: Crinocheta • Agnaridae • Alloniscidae • Armadillidae • Armadillidiidae • Balloniscidae • Bathytropidae • Berytoniscidae • Cylisticidae • Delatorreiidae • Detonidae • Eubelidae • Halophilosciidae • Olibrinidae • Oniscidae • Philosciidae • Platyarthridae • Porcellionidae • Pudeoniscidae • Rhyscotidae • Scleropactidae • Scyphacidae • Spelaeoniscidae • Stenoniscidae • Tendosphaeridae • Trachelipodidae Beyond these, some genera are of uncertain familial assignment such as: • Exalloniscus • Sunniva etc. ==Description and life cycle==

The woodlouse has a shell-like exoskeleton, which it must progressively shed as it grows. The moult takes place in two stages; The mother then appears to "give birth" to her offspring. A few species are also capable of reproducing asexually. Woodlice are attracted to small narrow places such as crevices or the underside of rocks in order to minimise water loss, likewise they are repulsed by bright light to avoid dessication under sunlight. They are usually nocturnal and are detritivores, feeding mostly on dead plant matter, preferring partially decayed or broken down material such as brown leafs. They break the plant material down by ingesting it, then later secrete it, and return to eat the secretion again; once bacteria and fungi has further broken it down. ==Ecology==

Ancestral Oniscidea species are littoral, such as the marine-intertidal sea slater (Ligia oceanica). They rely on gills (pleopodal endopods) for respiration and are thus bound to wetter environments. Other examples include some Haloniscus species from Australia (family Scyphacidae), and in the northern hemisphere several species of Trichoniscidae and Thailandoniscus annae (family Styloniscidae). Species for which aquatic life is assumed include Typhlotricholigoides aquaticus (Mexico) and Cantabroniscus primitivus (Spain). Many members of Oniscidea live in terrestrial, non-aquatic environments, breathing through pleopodal lungs(paddle-shaped posterior appendages) with pseudotrachea (branched air tubules). The pseudotrachea structure is well described in Porcellio scaber . Some Crinocheta members evolved to have spiracles that control airflow into their pleopodal lungs. Woodlice need moisture because they rapidly lose water by excretion and through their cuticle, and so are usually found in damp, dark places, such as under rocks and logs, although one species, the desert-dwelling Hemilepistus reaumuri, inhabits "the driest habitat conquered by any species of crustacean". Pericyphis is another xerophillic isopod with unique pseudotrachea structure, extending from the pleopods into their body cavity ''. Woodlice are eaten by a wide range of insectivores, including spiders of the genus Dysdera, such as the woodlouse spider Dysdera crocata, and land planarians of the genus Luteostriata, such as Luteostriata abundans. Platyarthrus hoffmannseggii is a species of woodlice that is often found in ants nests, feeding off their excretion. Other woodlice species are also sometimes found in ants nests, including Porcellio scaber. == Distribution ==

The oldest fossils of woodlice are known from the mid-Cretaceous around 100 million years ago and indeterminate specimens Charentese amber. The widespread distribution and diversification apparent of woodlice in the mid-Cretaceous implies that the origin of woodlice predates the breakup of Pangaea, likely during the Carboniferous. Woodlice themselves are thought to have evolved from ancestors that lived on the sea-bed, by way of intertidal forms which developed the ability to survive out of the water for longer and longer periods. The most primitive kinds of woodlice, Ligia for example, have evolved very little from this intertidal condition. ==Pill bugs and pill millipedes==

Pill bugs (woodlice of the family Armadillidiidae and Armadillidae) 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, share a similar diet, and conglobate as a defense mechanism. Pill millipedes and pillbugs appear superficially similar to the naked eye. This is an example of convergent evolution. These two groups can be distinguished in several ways. Glomeris millipedes have 19 (males) or 17 (females) pairs of legs as adults, while adult pill bugs only have 7 pairs of legs. Additionally, pill bugs have a thorax consisting of 7 body segments, 5 abdominal segments, and a pleotelson, while Glomeris millipedes lack a visually defined thorax and have 12 body segments total. While the uropods of pillbugs are relatively quite small, flipping a pill bug over will reveal the small uropod overlapping the pleotelson. Some woodlouse species, like Armadillidium maculatum, seem to display Batesian Mimicry to certain pill millipedes like Glomeris marginata. == Kinesis ==

As pests Although woodlice, like earthworms, are generally considered beneficial in gardens for their role in controlling certain pests, producing compost and overturning the soil, some species like those of the genus Armadillidium have also been known to feed on cultivated plants, such as ripening strawberries and tender seedlings. Woodlice can also invade homes in groups searching for moisture, and their presence can indicate dampness problems. They are not generally regarded as a serious household pest as they do not spread disease and do not damage sound wood or structures. They can be easily removed with the help of vacuum cleaners, chemical sprays, insect repellents, and insect killers, or by removing the dampness. As food The taste of foraged woodlice has been described as similar to that of other crustaceans, gaining them the colloquial name of "wood shrimp". However, woodlice can also have a "strong urine" taste likely due to high concentrations of uric acid in some species. As bio-indicators Woodlice have been used as bioindicators due to their ability to accumulate heavy metals in vesicles within their body, making them useful for detecting heavy metal contamination. As pets Woodlice have become a popular household pet for children as well as a hobby for invertebrate and insect enthusiasts or collectors. Porcellionidae (sowbugs) and Armadillidiidae (pillbugs) are seen often as they are the most common terrestrial isopods in Europe and North America. While some isopod species are kept purely as pets, some can also be used as an addition to bioactive terrariums, due to their ability to break down decaying organic materials. Other morphs are the result of dominant or recessive mutations, as seen with 'T+/T− Albino' and 'Whiteout' (several spp.). As an example, T+ albino isopods are the result of an isopod being born without the ability to produce melanin, removing all black pigmentation. However, they are believed to be tyrosinase-positive (hence the T+), and therefore can still create some darker pigments such as brown and purple. T− albino isopods are thought to lack both melanin and tyrosinase, and therefore only express light yellows, oranges, and white. Confusion can often arise due to the rate at which unidentified or undescribed isopod species are introduced to the hobby. This has contributed significantly to the genus Cubaris being considered a wastebasket taxon, as many of the unidentified or undescribed isopod species are incorrectly labelled as "Cubaris sp." even when they do not fit the formal description of the genus. ==See also==