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Sicarius (spider)
Encyclopedia
Sicarius is a genus
of venomous spider
s, 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.
, in (South America
and Africa
), known primarily for their self-burying behavior. All have six eyes arranged in three groups of two (diads). Sicarius resembles the crab spiders of the family Thomisidae and the members of the family Homalonychidae
. However, Sicarius lacks the characteristic violin-shaped marking of their cousins, the recluse spider
s. 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), and can live for very long times without food or water.
The sicarius spiders are between one and two inches in length.
s (open sores) as large as 2.5 cm in diameter. The genus Sicarius may have more toxic venom than Loxosceles (particularly the African species), based on laboratory experiments with rabbits. Sicariids are found in barren deserts and are able to bury themselves partially in the sand. Because of this, humans seldom come in contact with them. The females produce egg sacs covered with a mixture of sand and silk. The genus is considered to be a living fossil in that it is both quite primitive and distributed in parts of the former Gondwanaland, the huge southern continent that separated during the Mesozoic
. One example of this genus is the six-eyed sand spider
, S. hahni, whose bite is capable of major systemic damage (and is often deadly). However, bites by this spider are rare.
A U.S. patent (number 6,998,389) has been awarded for a means for using Sicariidae venom as a treatment for cancer. http://www.pharmcast.com/Patents100/Yr2006/Feb2006/021406/6998389_Spider021406.htm
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...
of venomous spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s, the best known being the six-eyed sand 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...
of southern 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...
. It is also commonly known as assassin spiders for the relatively quick catching and killing of their prey.
Habitat and appearance
Sicarius 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). Sicarius resembles the crab spiders of the family Thomisidae and the members of the family Homalonychidae
Homalonychidae
The Homalonychidae are a very small spider family with three described species in one genus.They do not build webs and are typically found under rocks or dead vegetation. At least the two North American species live in deserts, to which they are adapted by color and specialized setae which allow...
. However, Sicarius lacks the characteristic violin-shaped marking of their cousins, the recluse spider
Recluse spider
The recluse spiders or brown spiders , also known as fiddle-back, violin spiders or reapers, are a venomous genus of spiders known for their necrotic bite, which sometimes produces a characteristic set of symptoms known as Loxoscelism...
s. 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), and can live for very long times without food or water.
The sicarius spiders are between one and two inches in length.
Venom components and effects
The spiders of this genus (along with the recluse spiders) have potent tissue-destroying venoms containing the dermonecrotic agent, sphingomyelinase D, which is otherwise found only in a few pathogenic bacteria. This venom 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 2.5 cm in diameter. The genus Sicarius may have more toxic venom than Loxosceles (particularly the African species), based on laboratory experiments with rabbits. Sicariids are found in barren deserts and are able to bury themselves partially in the sand. Because of this, humans seldom come in contact with them. The females produce egg sacs covered with a mixture of sand and silk. The genus is considered to be a living fossil in that it is both quite primitive and distributed in parts of the former Gondwanaland, the huge southern continent that separated during the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
. One example of this genus is the six-eyed sand 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...
, S. hahni, whose bite is capable of major systemic damage (and is often deadly). However, bites by this spider are rare.
A U.S. patent (number 6,998,389) has been awarded for a means for using Sicariidae venom as a treatment for cancer. http://www.pharmcast.com/Patents100/Yr2006/Feb2006/021406/6998389_Spider021406.htm
Species
- Sicarius albospinosus Purcell, 1908 (South Africa)
- Sicarius crustosus (Nicolet, 1849) (Chile)
- Sicarius damarensis Lawrence, 1928 (Namibia)
- Sicarius deformis (Nicolet, 1849) (Chile)
- Sicarius dolichocephalus Lawrence, 1928 (Namibia)
- Sicarius fumosus (Nicolet, 1849) (Chile)
- Sicarius gracilis (Keyserling, 1880) (Peru)
- Sicarius hahni (Karsch, 1878) (Namibia)
- Sicarius lanuginosus (Nicolet, 1849) (Chile)
- Sicarius minoratus (Nicolet, 1849) (Chile)
- Sicarius nicoleti (Keyserling, 1880) (Chile)
- Sicarius patagonicus Simon, 1919 (Argentina)
- Sicarius peruensis (Keyserling, 1880) (Peru)
- Sicarius rubripes (Nicolet, 1849) (Chile)
- Sicarius rugosus (F. O. P.-Cambridge, 1899) (El Salvador, Costa Rica)
- Sicarius rupestris (Holmberg, 1881) (Argentina)
- Sicarius spatulatus Pocock, 1900 (South Africa)
- Sicarius terrosus (Nicolet, 1849) (Chile, Argentina, Peru)
- Sicarius terrosus yurensis Strand, 1908 (Peru)
- Sicarius testaceus Purcell, 1908 (South Africa)
- Sicarius tropicus (Mello-Leitão, 1936) (Brazil)
- Sicarius utriformis (Butler, 1877) (Galapagos Is.)
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.