Difference between revisions of "Louse" - New World Encyclopedia
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| − | '''Louse''' (plural: '''lice''') is any of the small, wingless, dorsoventally flattened [[insect]]s comprising the [[Neoptera|neopteran]] order '''Phthiraptera'''. This order of over 3,000 species mostly | + | '''Louse''' (plural: '''lice''') is any of the small, wingless, dorsoventally flattened [[insect]]s comprising the [[Neoptera|neopteran]] order '''Phthiraptera'''. This order of over 3,000 species consists mostly of biting, chewing, or sucking members that are obligate external parasites or scavengers on [[bird]]s and [[mammal]]s. |
| + | Also known as '''fly babies''', every [[birds|avian]] order and most [[mammals|mammalian]] orders are infected with these parasites. However, they are not found on [[Monotreme]]s (the [[platypus]] and the [[echidnas]] or spiny anteaters) and a few [[eutheria]]n orders, namely the [[bat]]s (Chiroptera), [[Cetacea|whales, dolphins and porpoises]] (Cetacea), and [[pangolin]]s (Pholidota). | ||
| − | Three of the sucking lice of the suborder Anoplura are well-known external parasites on humans | + | Three of the sucking lice of the suborder Anoplura are well-known external parasites on humans: ''Pediculosis humanus capitis'' (head lice), ''Pediculosis humanus corporis'' (body lice), and ''Phthirus pubic'' (pubic lice). While lice infestations are not dangerous by themselves, they can be a serious health problem given that some lice can be vectors carrying organisms that cause other diseases, such as trench fever, epidemic typhus, and relapsing fever (Frey 2002). |
| − | + | Historically, the lice have been divided into two main groups, the sucking lice of the suborder Anoplura and the chewing lice of the order Mallophaga. However, Mallophaga now is considered to be paraphyletic and generally the Phthiraptera now are divided into four suborders. | |
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| + | The term lice often is used more generally for parasitic animals that are not part of Phthiraptera, such as fish lice, which are a group of parasitic crustaceans, and book lice, which are insects that received their name from feeding on the paste used in binding books. | ||
==Description== | ==Description== | ||
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A louse's egg is commonly called a nit. Lice attach their eggs to their host's hair with specialized saliva which results in a bond that is very difficult to separate without specialized products. Living lice eggs tend to be pale white. Dead lice eggs are more yellow. Lice are very annoying and are difficult to remove, but not impossible. | A louse's egg is commonly called a nit. Lice attach their eggs to their host's hair with specialized saliva which results in a bond that is very difficult to separate without specialized products. Living lice eggs tend to be pale white. Dead lice eggs are more yellow. Lice are very annoying and are difficult to remove, but not impossible. | ||
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==Classification== | ==Classification== | ||
Revision as of 23:57, 14 August 2008
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 Light micrograph of Fahrenholzia pinnata
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Anoplura |
Louse (plural: lice) is any of the small, wingless, dorsoventally flattened insects comprising the neopteran order Phthiraptera. This order of over 3,000 species consists mostly of biting, chewing, or sucking members that are obligate external parasites or scavengers on birds and mammals.
Also known as fly babies, every avian order and most mammalian orders are infected with these parasites. However, 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).
Three of the sucking lice of the suborder Anoplura are well-known external parasites on humans: Pediculosis humanus capitis (head lice), Pediculosis humanus corporis (body lice), and Phthirus pubic (pubic lice). While lice infestations are not dangerous by themselves, they can be a serious health problem given that some lice can be vectors carrying organisms that cause other diseases, such as trench fever, epidemic typhus, and relapsing fever (Frey 2002).
Historically, the lice have been divided into two main groups, the sucking lice of the suborder Anoplura and the chewing lice of the order Mallophaga. However, Mallophaga now is considered to be paraphyletic and generally the Phthiraptera now are divided into four suborders.
The term lice often is used more generally for parasitic animals that are not part of Phthiraptera, such as fish lice, which are a group of parasitic crustaceans, and book lice, which are insects that received their name from feeding on the paste used in binding books.
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 are reflected in their size (0.5–8 mm), stout legs, and claws which are adapted to cling tightly to hair, fur and feathers, and that they are wingless and dorsoventrally flattened.
Lice feed on skin (epidermal) debris, feather parts, [Chlorine] sebaceous secretions and blood. A louse's color varies from pale beige to dark grey; however, if feeding on blood, it may become considerably darker.
A louse's egg is commonly called a nit. Lice attach their eggs to their host's hair with specialized saliva which results in a bond that is very difficult to separate without specialized products. Living lice eggs tend to be pale white. Dead lice eggs are more yellow. Lice are very annoying and are difficult to remove, but not impossible.
),
Classification
The order has traditionally been divided into two suborders; the sucking lice (Anoplura) and chewing lice (Mallophaga), however, recent classifications suggest that the Mallophaga are paraphyletic and four suborders are now recognised:
- Anoplura: sucking lice, including head and pubic lice (see also Pediculosis or Head lice)
- Rhyncophthirina: parasites of elephants and warthogs
- Ischnocera: avian lice
- Amblycera: chewing lice, a primitive order of lice
- Amblycera: Jumping Lice have very strong hind legs and can jump a distance of three feet
It has been suggested[attribution needed] that the order is contained by the Troctomorpha suborder of Psocoptera.
Lice and humans
Humans are unique in that they 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 at approximately 70,000 B.C.E.[1]
Recent DNA evidence suggests that pubic lice spread to the ancestors of humans approximately 3.3 million years ago from the ancestors of gorillas 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 infesting humans.[2]
Gallery
The chewing louse Damalinia limbata is found on Angora goats. The male louse (right) is typically smaller than the female (left), whose posterior margin of the abdomen is more rounded than those of male lice.
Diagram of a louse, by Robert Hooke, 1667.
Trichodectes canis, the biting dog louse
ReferencesISBN links support NWE through referral fees
- ↑ John Travis (2003-08-23). The naked truth? Lice hint at a recent origin of clothing 164 (8): 118.
- ↑ 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.
- Frey, R.J. 2002. Lice infestation. Pages 1994-1996 in J.L. Longe (ed.), The Gale Encyclopedia of Medicine, 2nd edition, volume 3. Detroit: Gale Group/Thomson Learning. ISBN 0787654922.
- Integrated Taxonomic Information System (ITIS). 2004. Phthiraptera Haeckel, 1896 ITIS Taxonomic Serial No.: 624282. Retrieved August 14, 2008.
- Integrated Taxonomic Information System (ITIS). 2007. Mallophaga ITIS Taxonomic Serial No.: 103337 . Retrieved August 14, 2008.
See Also
- Pest
- Use of DNA in forensic entomology
External links
- Lice Pest Control Information - National Pesticide Information Center
- Bed-hopping led humans to 3 million-year itch
- www.phthiraptera.org has extensive scientific information.
- body and head lice on the UF / IFAS Featured Creatures Web site
- crab louse on the UF / IFAS Featured Creatures Web site
- WebMD Lice Info
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