Topics: Woodlouse, Arthropod, Crustacean Pages: 5 (1783 words) Published: May 11, 2013
A woodlouse is a crustacean with a rigid, segmented, long exoskeleton and fourteen jointed limbs. Woodlice form the suborderOniscidea within the order Isopoda, with over 3,000 known species. The woodlouse has a shell-like exoskeleton, which it must progressively shed as it grows. The moult takes place in two stages; the back half is lost first, followed two or three days later by the front. This method of moulting is different from that of most arthropods, which shed their cuticle in a single process. Metabolic rate is temperature-dependent in woodlice. In contrast to mammals and birds, invertebrates are not "self heating": the external environmental temperature relates directly to their rate of respiration. A female woodlouse will keep fertilised eggs in a marsupium on the underside of her body until they hatch into small, white offspring. The mother then appears to "give birth" to her offspring. Females are also capable of reproducingasexually.[19] Living in a terrestrial environment, woodlice breathe through trachea-like lungs in their paddle-shaped hind legs (pleopods), called 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, Hemilepistus reaumuri, inhabits "the driest habitat conquered by any species of crustacean".[21]They are usually nocturnal and are detritivores, feeding mostly on dead plant matter. Few woodlice have returned to water. Evolutionary ancient species are amphibious, such as the marine-intertidal sea slater (Ligia oceanica), which belongs to family Ligiidae. Other examples include some Haloniscus species from Australia (family Scyphacidae), and in the northern hemisphere several species ofTrichoniscidae and Thailandoniscus annae (family Styloniscidae). Species for which aquatic life is assumed include Typhlotricholigoides aquaticus(Mexico) and Cantabroniscus primitivus (Spain).[22]

The specialist predator Dysdera crocata feeds exclusively on woodlice. Woodlice are eaten by a wide range of insectivores, but the only animals known to prey exclusively on woodlice are spiders of the genus Dysdera, such as the woodlouse spider Dysdera crocata.[9]

Woodlice belong to the class of arthropods known as crustaceans, which is a predominantly aquatic group containing the crabs and lobsters. Although they now live on land the woodlice have not completely shaken off their aquatic habits. Their skins are not completely waterproof, and the animals very soon desiccate in a dry environment. This is why almost all of them are confined to damp places and why they only come out to feed at night, when the air is cooler and damper. Many of the species can breathe only if their bodies are covered with a thin film of moisture, although they would soon drown if immersed in water

As with the Millipedes and Centipedes, woodlice belong to the Phylum Arthropoda and I don't think that there is anybody who doesn't know what a woodlouse is...but boy!! do they have some colloquial names, these include; bibble-bugs, sow-bugs, cud-worms, tiggy-hogs, shoe-laces, sink-lice, slaters, and coffin cutters. A total of 42 species of woodlice have been recorded from the British Isles, as far as I know, but no more than 29 of these can be considered native to these islands. Some of the others have been imported with plants and have become well established as Synanthropes (this is a name that means "with man", that is, we provide the ideal living conditions in our house, greenhouse, cafe and kitchens etc.), but obviously there will be a restriction with distribution. Many of our native species are confined to coastal habitats or to woodlands, and only six species can be regarded as garden animals. All woodlice are much more abundant on lime rich soils, than in other regions, as they need the lime for...
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