Louse

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Phthiraptera

Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Subclass: Pterygota
Infraclass: Neoptera
Order: Phthiraptera
Haeckel, 1896
Suborders

Anoplura
Rhyncophthirina
Ischnocera
Amblycera

Lice (singular: louse), (order Phthiraptera), also known as fly babies or Nits, are an order of over 3,000 species of wingless insects; three of which are classified as human disease agents. They are obligate ectoparasites of every avian and most mammalian orders. They are not found on Monotremes (the platypus and the echidnas or spiny anteaters) and a few eutherian orders, namely the bats (Chiroptera), whales, dolphins and porpoises (Cetacea) and pangolins (Pholidota).

Contents

[edit] Description

As lice spend their entire lives on the host, they have developed adaptations which enable them to maintain close contact with the host. These adaptations include their size 0.5 to 8 millimetres (0.020 to 0.31 in), their stout legs, and their claws which allow them to cling tightly to hair, fur and feathers; other adaptations include being wingless and dorsoventrally flattened. Lice are attracted to clean hair, taking too many showers or baths a day could be a major factor to attracting lice. Lice do not like oils. One of the best ways to get rid of lice is by bathing your head in olive oil. Lice have no ocelli and only small compound eyes; many species have no eyes at all. Other distinguishing features include short antennae, the absence of abdominal cerci, and the thoracic segments being at least partially fused. Most lice have relatively simply chewing mouthparts, but in some they are highly adapted for piercing and sucking.[1]

Lice cannot jump or fly.

[edit] Biology

Most lice are scavengers, feeding on skin and other debris found on the host's body, but some species feed on sebaceous secretions and blood. Most are found only on specific types of animal, and, in some cases, only to a particular part of the body; some animals are known to host up to fifteen different species, although one to three is typical for mammals, and two to six for birds. For example, in humans, different species of louse inhabit the scalp and pubic hair. Lice generally cannot survive for long if removed from their host.[1]

A louse's color varies from pale beige to dark gray; however, if feeding on blood, it may become considerably darker. They mostly like clean hair. Female lice are usually more common than the males, and some species are even known to be parthenogenetic. A louse's egg is commonly called a nit. Many lice attach their eggs to their host's hair with specialized saliva; the saliva/hair bond is very difficult to sever without specialized products. Lice inhabiting birds, however, may simply leave their eggs in parts of the body inaccessible to preening, such as the interior of feather shafts. Living lice eggs tend to be pale white. Dead lice eggs are more yellow.[1]

Lice are exopterygotes, being born as miniature versions of the adult, known as nymphs. The young moult three times before reaching the final adult form, which they usually reach within a month of hatching.[1]

[edit] Classification

The order has traditionally been divided into two suborders, the sucking lice (Anoplura) and the chewing lice (Mallophaga); however, recent classifications suggest that the Mallophaga are paraphyletic and four suborders are now recognised:

It has been suggested[weasel words] that the order is contained by the Troctomorpha suborder of Psocoptera.

[edit] Lice and humans

For information about human infestation, see Pediculosis. For information on treatment see Treatment of human head lice.

Humans host three different kinds of lice: head lice, body lice (which live mainly in clothing), and pubic lice. The DNA differences between head lice and body lice provide corroborating evidence that humans started wearing clothes about 72,000 years ago, give or take 42,000 years.[2]

Recent DNA evidence suggests that pubic lice spread to humans approximately 3,000,000 years ago from the ancestors of humans by sharing the same bed or other communal areas with them, and are more closely related to lice endemic to gorillas than to other lice species which infest humans.[3]

Adult and nymphal lice can survive on sheep-shearers' moccasins for up to 10 days, but microwaving the footwear for five minutes in a plastic bag will kill the lice.[4]

Lice infestations can be controlled with lice combs, and medicated shampoos or washes.

[edit] Gallery

Search Wikimedia Commons Wikimedia Commons has media related to: Phthiraptera

Ricinus bombycillae, an Amblyceran louse from the bohemian waxwing

Trinoton anserinum, an Amblyceran louse from a mute swan.

Damalinia limbata is an Ischnoceran louse from goats. The male is smaller than the female.

Diagram of a louse, by Robert Hooke, 1667.

[edit] References

  1. ^ a b c d Hoell, H.V., Doyen, J.T. & Purcell, A.H. (1998). Introduction to Insect Biology and Diversity, 2nd ed.. Oxford University Press. pp. 407-409. ISBN 0-19-510033-6. 
  2. ^ John Travis (2003-08-23) ([dead link] – Scholar search). The naked truth? Lice hint at a recent origin of clothing. 164. Science News. pp. 118. http://www.sciencenews.org/articles/20030823/fob7.asp. 
  3. ^ David L Reed, Jessica E Light, Julie M Allen and Jeremy J Kirchman (2007). "Pair of lice lost or parasites regained: the evolutionary history of anthropoid primate lice". BMC Biology 5: 7. doi:10.1186/1741-7007-5-7. 
  4. ^ Sheep parasites Retrieved on 10 November 2008

[edit] See also

[edit] External links

Search Wiktionary Look up louse in Wiktionary, the free dictionary.


v • d • e
Human lice and pediculosis
Species
Infestation
Treatment
Other terms of interest

Cooties · Sucking louse · Louse
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