Louse

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Lice (singular: louse), (order Phthiraptera), also known as fly babies, are an order of over 3,000 species of wingless insects, classified as a disease in humans. They are obligate ectoparasites of every mammalian and avian order, with the notable exceptions of Monotremata (the platypus and the echidnas or spiny anteaters) and Chiroptera (bats).

Description

As lice spend their whole life 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, 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 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 orangeish.

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 that the order is contained by the Troctomorpha suborder of Psocoptera.

Lice and humans

Humans are unique in 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 approximately 72,000 years ago .

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 .

Gallery

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 University of Florida Featured Creatures
Crab Louse University of Florida Featured Creatures
WebMD Lice Info

References

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Last updated on Thursday March 13, 2008 at 16:39:33 PDT (GMT -0700)
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