Sicariidae

Taxobox
name = Recluse spiders


image_width = 250px
image_caption = Brown recluse spider
regnum = Animalia
phylum = Arthropoda
classis = Arachnida
ordo = Araneae
subordo = Araneomorphae
superfamilia = Scytodoidea
familia = Sicariidae
familia_authority = Keyserling, 1880
diversity_link = List of Sicariidae species
diversity = 2 genera, 122 species
range_

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range_map_width = 250px
subdivision_ranks = Genera
subdivision = "Loxosceles"
"Sicarius"
The spider family "Sicariidae" is a family of venomous spiders known for their necrotic venom. The members of this family, like most Haplogynae, have only six eyes, rather than eight (as is the norm for spiders). The family consists of two genera, "Loxosceles" and "Sicarius", and 122 species [http://research.amnh.org/entomology/spiders/catalog/COUNTS.html World Spider Catalog] . Well known spiders in this family include the brown recluse spider and the six-eyed sand spider.

Habitat and appearance

The genus "Loxosceles", commonly known as recluse spiders or violin spiders, is distributed nearly worldwide in warmer areas. The genus "Sicarius", or six-eyed crab spiders, are desert spiders that live in the Southern Hemisphere, in (South America and Africa), known primarily for their self-burying behavior. All have six eyes arranged in three groups of two (diads) and the violin spiders are usually brownish with a darker brown characteristic violin marking on the cephalothorax. "Sicarius" resembles the crab spiders of the family Thomisidae and lacks this marking. Individual "Sicarius" can live for as much as 15 years, which makes these among the longest-lived araneomorphae spiders (some tarantulas can live well over 20-30 years.) Most "Loxosceles" can live for one and a half to two years. Members of both genera can live for very long times without food or water.

Medical significance

Both genera have potent tissue-destroying venoms containing the dermonecrotic agent, sphingomyelinase D, which is otherwise found only in a few pathogenic bacteria. Thus, the venom of "Sicariidae" is highly necrotic in effect, capable of causing lesions (open sores) as large as a US quarter. The wounds take a long time to heal and may require skin grafts. If these open wounds get infected there can be serious consequences. Rarely, the venom is carried by the blood stream to internal organs causing systemic effects. The Chilean recluse ("Loxosceles laeta"), along with the African species of "Sicarius", reportedly have a more potent venom, which results in systemic involvement more often. [http://www.lclark.edu/~binford/SMDDistribution%20copy.pdf Greta J. Binford and Michael A. Wells, "The phylogenetic distribution of sphingomyelinase D activity in venoms of Haplogyne spiders", "Comparative Biochemistry and Physiology" Part B 135 (2003) 25–33]

Genera

*"Loxosceles" Heineken & Lowe, 1832 (worldwide)
*"Sicarius" Walckenaer, 1847 (South America, Africa, Galapagos)

References

ee also

* List of Sicariidae species
* Spider families

External links

* [http://www.arachnology.org/Arachnology/Pages/Reclusa.html Arachnology Home Pages: Loxosceles: Recluse spiders]
* [http://www.museums.org.za/bio/spiderweb/sicariid.htm Biodiversity Explorer: Family Sicariidae] (Beautiful photos of "Sicarius" and "Loxosceles"!)
* [http://research.amnh.org/entomology/spiders/catalog81-87/index.html Platnick, N.I. 2003. World Spider Catalog.]
* [http://spiders.ucr.edu/necrotic.html Vetter, R. 2003. Causes of Necrotic Wounds other than Brown Recluse Spider Bites.]
* [http://spiders.ucr.edu/myth.html Vetter, R. 2003. Myth of the Brown Recluse Fact, Fear, and Loathing.]
* [http://www.spiderpicturesandinfo.com/brown-recluse-spider/ Pictures of the Brown Recluse Spider]