The brown recluse, Sicariidae is a recluse spider with necrotic venom. Similar to those of other recluse spiders, their bites sometimes require medical attention. The brown recluse is one of three spiders in North America with dangerous venom, the others being the black widow and the Chilean recluse.
The recluse spiders, also known as brown spiders, fiddle-backs, violin spiders, and reapers, is a genus of spiders that was first described by R. T. Lowe in 1832. They are venomous spiders known for their bite, which sometimes produces a characteristic set of symptoms known as loxoscelism.
Sicariidae is a family of six-eyed venomous spiders known for their potentially necrotic bites. The family consists of three genera and about 160 species. Well known spiders in this family include the brown recluse spider and the six-eyed sand spider.
Anyphaenidae is a family of araneomorph spiders, sometimes called anyphaenid sac spiders. They are distinguished from the sac spiders of the family Clubionidae and other spiders by having the abdominal spiracle placed one third to one half of the way anterior to the spinnerets toward the epigastric furrow on the underside of the abdomen. In most spiders the spiracle is just anterior to the spinnerets. Like clubionids, anyphaenids have eight eyes arranged in two rows, conical anterior spinnerets and are wandering predators that build silken retreats, or sacs, usually on plant terminals, between leaves, under bark or under rocks. There are more than 600 species in over 50 genera worldwide.
The Mediterranean recluse spider is a species of spider that originated in the Mediterranean region as its name implies, but can now be found in many parts of the world and is listed as one of the most invasive spiders worldwide. Usually dwelling in caves, the spiders will also inhabit basements and tunnels. Their webs shelter their egg sacs, which hatch into young that molt as they grow. The spider hunts at night and eats species including silverfish and cockroaches, and they usually target smaller insects.
Wandering spiders (Ctenidae) are a family of spiders that includes the Brazilian wandering spiders. These spiders have a distinctive longitudinal groove on the top-rear of their oval carapace similar to those of the Amaurobiidae. They are highly defensive and venomous nocturnal hunters. Wandering spiders are known to hunt large prey, for example hylid species Dendropsophus branneri. Despite their notoriety for being dangerous, only a few members of Phoneutria have venom known to be hazardous to humans, but the venoms of this family are poorly known, so all larger ctenids should be treated with caution.
Hexophthalma hahni, known along with other members of the genus as the six-eyed sand spider, is a member of the family Sicariidae, found in deserts and other sandy places in southern Africa. Due to their flattened stance and laterigrade legs, they are also sometimes known as six-eyed crab spiders. Its specific name honours Carl Wilhelm Hahn.
The Chilean recluse spider, Loxosceles laeta, is a highly venomous spider of the family Sicariidae. In Spanish, it is known as araña de rincón, or "corner spider"; in Brazilian Portuguese, as aranha-marrom or "brown spider". It is considered by many to be the most dangerous of recluse spiders, and its bites often result in serious systemic reactions, up to and including death.
Lycosa is a genus of wolf spiders distributed throughout most of the world. Sometimes called the "true tarantula", though not closely related to the spiders most commonly called tarantulas today, Lycosa spp. can be distinguished from common wolf spiders by their relatively large size. This genus includes the European Lycosa tarantula, which was once associated with tarantism, a dubious affliction whose symptoms included shaking, cold sweats, and a high fever, asserted to be curable only by the traditional tarantella dance. No scientific substantiation of that myth is known; the venom of Lycosa spiders is generally not harmful.
Loxoscelism is a condition occasionally produced by the bite of the recluse spiders. The area becomes dusky and a shallow open sore forms as the skin around the bite dies (necrosis). It is the only proven type of necrotic arachnidism in humans. While there is no known therapy effective for loxoscelism, there has been research on antibiotics, surgical timing, hyperbaric oxygen, potential antivenoms and vaccines. Because of the number of diseases that may mimic loxoscelism, it is frequently misdiagnosed by physicians.
Scytodes globula, the Chilean tiger spider, is a predatory spider of the family Scytodidae. In Spanish, it is known as araña tigre, or "tiger spider", but is also well known as "long-legged spider" or "spitting spider". It has achieved fame by being the only natural predator of the extremely common and dangerous Chilean recluse spider.
The pathophysiology of a spider bite is due to the effect of its venom. A spider envenomation occurs whenever a spider injects venom into the skin. Not all spider bites inject venom – a dry bite, and the amount of venom injected can vary based on the type of spider and the circumstances of the encounter. The mechanical injury from a spider bite is not a serious concern for humans. Some spider bites do leave a large enough wound that infection may be a concern. However, it is generally the toxicity of spider venom that poses the most risk to human beings; several spiders are known to have venom that can cause injury to humans in the amounts that a spider will typically inject when biting.
Hexophthalma is a genus of spiders in the family Sicariidae. Although the genus was originally erected in 1878, it was merged into the genus Sicarius in the 1890s, and remained unused until revived in 2017, when it was discovered that the African species then placed in Sicarius were distinct. The English name six-eyed sand spiders is used for members of the genus, particularly Hexophthalma hahni.
Sicarius thomisoides is a species of spider in the family Sicariidae, found in Chile. It is the type species of the genus Sicarius. Its correct name has been the source of confusion. It has often been known by the synonym Sicarius terrosus, a name which has also often been used incorrectly for other species.
Sicarius ornatus is a species of venomous spider found in South America (Brazil). It has a highly toxic venom like the other South American sicariid, Loxosceles laeta and the African Hexophthalma hahni, but there are few human bites recorded. Its venom has active sphingomyelinase D, and can lead to a severe pathology.
Sicarius tropicus is a species of six-eyed sand spider (Sicarius) endemic in South American caatinga in Brazil. Like related spiders, it is venomous, but only one medically-significant bite has been recorded, causing dermonecrotic lesions in a 17-year-old boy.
