Sicariidae
Encyclopedia
Sicariidae is a family
of six-eyed venomous spiders
known for their necrotic bites. The members of this family are haplogyne by definition (instead of the most spiders that possess eight eyes). The family consists of two genera
, Loxosceles and Sicarius, and contains about 120 species
. Well known spiders in this family include the brown recluse spider
and the assassin spider
.
, 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 tarantula
s 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.
s (open sores) as large as a US quarter (about one inch or 25mm in diameter). 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.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of six-eyed venomous spiders
Spider bite
A spider bite is an injury resulting from the bites of spiders or other closely related arachnids.Spiders are active hunters and rely heavily on their bites to paralyze and kill their prey before consuming it. They also bite in self defense...
known for their necrotic bites. The members of this family are haplogyne by definition (instead of the most spiders that possess eight eyes). The family consists of two genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
, Loxosceles and Sicarius, and contains about 120 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. Well known spiders in this family include the brown recluse spider
Brown recluse spider
The brown recluse spider or violin spider, Loxosceles reclusa, is a member of the family Sicariidae . The spider has a venomous bite....
and the assassin spider
Six-eyed sand spider
The six-eyed sand spider is a medium-sized spider with body measuring 8 to 15 mm and legs spanning up to 50 mm, found in deserts and other sandy places in southern Africa. It is a member of the Sicariidae family; close relatives may be found in both Africa and in South America, and its...
.
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 assassin spiders, are desert spiders that live in the Southern HemisphereSouthern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
, in (South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
), 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
Araneomorphae
The Araneomorphae are a suborder of spiders. They are distinguished by having fangs that oppose each other and cross in a pinching action, in contrast to the Mygalomorphae , which have fangs that are nearly parallel in alignment.- Distinguishing characteristics :Note the difference in the...
spiders (some tarantula
Tarantula
Tarantulas comprise a group of often hairy and often very large arachnids belonging to the family Theraphosidae, of which approximately 900 species have been identified. Some members of the same Suborder may also be called "tarantulas" in the common parlance. This article will restrict itself to...
s 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 lesionLesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
s (open sores) as large as a US quarter (about one inch or 25mm in diameter). 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
Chilean recluse
The Chilean recluse spider is a venomous spider, Loxosceles laeta, of the family Sicariidae . In Spanish, it is known as , or "corner spider"; in Portuguese, as or "brown spider"...
(Loxosceles laeta), along with the African species of Sicarius, reportedly have a more potent venom, which results in systemic involvement more often.
Genera
- Loxosceles Heineken & Lowe, 1832 (worldwide)
- SicariusSicarius (spider)Sicarius is a genus of venomous spiders, the best known being the six-eyed sand spider of southern Africa. It is also commonly known as assassin spiders for the relatively quick catching and killing of their prey.-Habitat and appearance:...
WalckenaerCharles Athanase WalckenaerBaron Charles Athanase Walckenaer was a French civil servant and scientist.-Biography:Walckenaer was born in Paris and studied at the universities of Oxford and Glasgow. In 1793 he was appointed head of the military transports in the Pyrenees, after which he pursued technical studies at the École...
, 1847 (South America, Africa, Galapagos)
External links
- Arachnology Home Pages: Loxosceles: Recluse spiders
- Biodiversity Explorer: Family Sicariidae (Beautiful photos of Sicarius and Loxosceles!)
- Platnick, N.I. 2003. World Spider Catalog.
- Vetter, R. 2003. Causes of Necrotic Wounds other than Brown Recluse Spider Bites.
- Vetter, R. 2003. Myth of the Brown Recluse Fact, Fear, and Loathing.
- Pictures of the Brown Recluse Spider