The black widow spider (Latrodectus spp.) is a spider notorious for its neurotoxic venom. It is a large widow spider found throughout the world and commonly associated with urban habitats or agricultural areas. Although the name 'black widow spider' is most commonly used to refer to the three North American species best known for their dark coloration, black hair and red hourglass pattern, occasionally it is applied to several other members of a the Latrodectus (widow spider) genus in which there are 31 recognized species including the Australian red-back, brown widow spider (sometimes called the gray widow), and the red widow spider. In South Africa, widow spiders are also known as the button spiders. Diversity 111 families, 40,000 species Suborders Mesothelae Mygalomorphae Araneomorphae  See table of families Wikispecies has information related to: Spiders Spiders are predatory invertebrate animals that have two body segments, eight legs, no chewing mouth parts and no wings. ... A neurotoxin is a toxin that acts specifically on nerve cells – neurons – usually by interacting with membrane proteins such as ion channels. ... It has been suggested that Snake poison be merged into this article or section. ... Species Approx. ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... For other uses, see Hourglass (disambiguation). ... The scientific term for the widow spider is a member of the spider genus Latrodectus. ... For other uses, see Species (disambiguation). ... Binomial name Thorell, 1870 The redback spider (Latrodectus hasselti) is a potentially dangerous spider native to Australia. ... Binomial name Latrodectus geometricus Koch, 1841 The Brown widow spider is a close relation to the more famous black widow spider. ... Binomial name Latrodectus bishopi (Fabricius, 1775) Latrodectus bishopi is the scientific name for the Red Widow Spider, which is found only in select parts of Florida. ... Species Approx. ...

Currently, there are three recognized species of black widow found in North America: The southern black widow (L. mactans), the northern black widow (L. variolus), and the western black widow (L. hesperus). As the name indicates, the southern widow is primarily found (and is indigenous to) the southeastern United States, ranging from Florida to New York, and west to Texas, Oklahoma and they run particularly rampant in parts of Arizona. Official language(s) English Capital Tallahassee Largest city Jacksonville Largest metro area Miami metropolitan area Area  Ranked 22nd  - Total 65,795[1] sq mi (170,304[1] km²)  - Width 361 miles (582 km)  - Length 447 miles (721 km)  - % water 17. ... This article is about the state. ... Official language(s) No official language See languages of Texas Capital Austin Largest city Houston Largest metro area Dallas–Fort Worth–Arlington Area  Ranked 2nd  - Total 261,797 sq mi (678,051 km²)  - Width 773 miles (1,244 km)  - Length 790 miles (1,270 km)  - % water 2. ... Official language(s) None Capital Oklahoma City Largest city Oklahoma City Largest metro area Oklahoma City metro area Area  Ranked 20th  - Total 69,898 sq mi (181,196 km²)  - Width 230 miles (370 km)  - Length 298 miles (480 km)  - % water 1. ... Official language(s) English Spoken language(s) English 74. ...

The northern black widow is found primarily in the northeastern U.S. and southeastern Canada (only on the Bruce Peninsula), though its ranges overlap that of L. mactans quite a bit. The western widow is found in the western half of the United States, as well as in southwestern Canada and much of Mexico. Prior to 1970, when the current taxonomic divisions for North American black widows were set forth by Kaston, all three varieties were classified as a single species, L. mactans. As a result, there exist numerous references which claim that "black widow" (without any geographic modifier) applies to L. mactans alone. As common usage of the term "black widow" makes no distinction between the three species (and many laypersons are unaware of the differences between them), and as the three species have much in common, this article treats all three species of black widow equally. Except where otherwise indicated, the remainder of the article applies to all three of the above species. Map of Southern Ontario showing Bruce Peninsula in red. ...

Description

Only young female black widow spiders are gloss black with an hourglass shaped marking on the underside of its abdomen which, although most commonly red, may range in color from white to yellow to various shades of orange and red. They also bear a small, usually red (colors vary) dot near the spinnerets, which is separate from the hourglass. In L. variolus, the two halves of the hourglass shape may be separated into two separate patches. A large female black widow spider can grow to about 1.5 inches (37 mm), counting legspan. The body is about 0.5-0.6 inches (12-15 mm). Male black widow spiders are half the size of the female or smaller. They have longer legs and a smaller abdomen in relation to their body size. They are also usually dark brown with varying colors of stripes/dots, with no hourglass mark. Adult males can be distinguished from juvenile females by their more-slender body, longer legs and large pedipalps typical of most other male spiders. Male European garden spider with swollen pedipalps Pedipalps are a pair of feelers on a spiders face. ...

As with many venomous creatures, the brightly colored markings serve as a warning to predators. Eating a black widow will normally not kill a small predator (birds, et cetera), but the sickness that follows digestion is enough for the creature to remember that the bright red marking means "do not eat." Because the adult female black widow typically hangs and moves about its web upside down, its hourglass is on its front. Juvenile female widows spend a large quantity of time in search of an optimal environment. Once an optimal location is found, adult female widows often spend their entire lives in one place. Because juvenile females must first find this optimal location, they bear brightly colored marks upon their backs, so that they may be seen by predators when the widow is walking using its legs. Males bear similar marks to the females to serve as warning while they are searching for mates, however, the marks are not as prominent (not as brightly colored, or as large). Males, being less venomous, are less of a threat to predators, so having less prominent but similar marks helps predators to better judge their prey (some large birds can eat male widows without adverse effect, and so only avoid female spiders; those who cannot eat any widow without adverse effect eat nothing with the marks). Female juveniles develop an hourglass before the dorsal markings are shed. As is characteristic of all arthropods, black widow spiders have a hard exoskeleton composed of chitin and protein. ^[1] Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

Black widow with a fly

Image File history File linksMetadata Download high-resolution version (1297x1297, 879 KB) Summary Photo of a black widow taken in my backyard. ... Image File history File linksMetadata Download high-resolution version (1297x1297, 879 KB) Summary Photo of a black widow taken in my backyard. ...

Prey

Black widow spiders typically prey on a variety of insects, but occasionally they do feed upon woodlice, diplopods, chilopods and other arachnids.^[2] When the prey is entangled by the web, L. mactans quickly comes out of its retreat, wraps the prey securely in its strong web, then punctures and envenomates its prey. The venom takes about ten minutes to take effect; in the mean time, the prey is held tightly by the spider. When movements of the prey cease, digestive enzymes are released into the wound. The black widow spider then carries its prey back to its retreat before feeding.^[3] Infraorders and Families Not necessarily a complete list Infraorders: Ligiamorpha Tylomorpha Families: Dubioniscidae Irmaosidae Pseudarmadillidae Scleropactidae Armadillidium vulgare A woodlouse, also known as a pill bug (genus Armadillidium only), armadillo bug, sow bug, slater, ball bug, or roley-poley, is a terrestrial crustacean with a rigid, segmented, calcareous exoskeleton and... Subclasses Helminthomorpha Penicillata Pentazonia Millipedes or millepedes (Class Diplopoda, previously also known as Chilognatha) are very elongated arthropods with cylindrical bodies that have two pairs of legs for each one of their 20 to 100 or more body segments (except for the first segment behind the head which dont... For other articles with the word centipede, go to Centipede (disambiguation). ... Orders Acarina Amblypygi Araneae Opiliones Palpigradi Pseudoscorpionida Ricinulei Schizomida Scorpiones Solifugae Uropygi The arachnids, Arachnida, are a class of invertebrate animals in the subphylum Chelicerata. ...

Reproduction

Black Widow With egg sacs

When a male is mature, he spins a sperm web, deposits semen on it, and charges his palpi with the sperm. Black widow spiders reproduce sexually when the male inserts his palpus into the female's spermathecal openings. The female deposits her eggs in a globular silken container in which they remain camouflaged and guarded. A female black widow spider can produce four to nine egg sacs in one summer, each containing about 100-400 eggs. Usually, eggs incubate for twenty to thirty days. Rarely do more than one hundred survive through this process. On average, thirty will survive through the first molting, due to cannibalism, lack of food, or lack of proper shelter. It takes two to four months for black widow spiders to mature enough to breed, however full maturation typically takes six to nine months. The females can live for up to five years, while a male's lifespan is much shorter. Contrary to popular belief, the female only rarely eats the male after mating, and L. mactans is the only black widow species for which this form of sexual cannibalism has been observed in the wild. Lifespans depend upon environment, with shelter being the greatest determining factor and food the second greatest.^[4] Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Male European garden spider with swollen pedipalps Pedipalps are a pair of feelers on a spiders face. ... Ecdysis is the molting of the cuticula in arthropods and related groups (Ecdysozoa). ... Cannibal redirects here. ... Sexual cannibalism is a special case of cannibalism in which a female organism kills and consumes male of the same species before, during, or after copulation. ...

Natural enemies

There are various parasites and predators of widow spiders in North America, though apparently none of these have ever been evaluated in terms of augmentation programs for improved biocontrol. Parasites of the egg sacs include the flightless scelionid wasp Baeus latrodecti, and members of the chloropid fly genus Pseudogaurax. Predators of the adult spiders include a few wasps, most notably the blue mud dauber, Chalybion californicum, and the spider wasp Tastiotenia festiva. Other species will occasionally and opportunistically take widows as prey, but the preceding all exhibit some significant specific preference for Latrodectus. A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... Biological control of pests and diseases Overview A key belief of the organic gardener is that diversity furthers health. ... Subfamilies Scelioninae Teleasinae Telenominae The Hymenopteran family Scelionidae is a very large cosmopolitan group (over 3000 described species in some 160 genera) of exclusively parasitoid wasps, mostly small (0. ... Genera More than 160 See list of chloropid genera Chloropidae is a family of flies commonly known as frit flies or grass flies. ... Families Some Sphecidae and Crabronidae Mud dauber (sometimes dirt dauber or dirt dobber in the southern U.S.) is a name commonly applied to a number of wasps from either the family Sphecidae or Crabronidae that build their nests from mud. ... Binomial name Drury, 1773 The blue mud dauber is a metallic blue species of mud dauber wasp that preys primarily on black widow spiders [1]. It does not build a nest, but uses nests abandoned by other mud dauber wasps. ... Subfamilies Ceropalinae Ctenocerinae Pepsinae Pompilinae Wasps in the family Pompilidae are commonly called wasp spiders. ... The scientific term for the widow spider is a member of the spider genus Latrodectus. ...

Venom

See also: Spider bite

Although their venom is extremely potent, (15 times more potent than that of the rattlesnakes; it is also reported to be much more potent than the venom of cobras and coral snakes), these spiders are not especially large. Spiders bite but do not sting, though it can sometimes feel like being stung. Compared to many other species of spiders, their chelicerae are not very large or powerful. In the case of a mature female, the hollow, needle shaped part of each chelicera, the part that penetrates the skin, is approximately 1.0 mm (about .04 inch) long, sufficiently long to inject the venom to a dangerous depth. The males, being much smaller, can inject far less venom and inject it far less deeply. The actual amount injected, even by a mature female, is very small in physical volume. When this small amount of venom is diffused throughout the body of a healthy, mature human, it usually does not amount to a fatal dose (though it can produce the very unpleasant symptoms of latrodectism). Deaths in healthy adults from Latrodectus bites are relatively rare in terms of the number of bites per thousand people. Only 63 deaths were reported in the United States between 1950 and 1989. On the other hand, the geographical range of the widow spiders is very great. As a result, far more people are exposed, world-wide, to widow bites than are exposed to bites of more dangerous spiders, so the highest number of deaths world-wide are caused by members of their genus. Widow spiders have more potent venom than most spiders, and prior to the development of antivenom, 5% ^{[citation needed]} of reported bites resulted in fatalities. The venom can cause a swelling up to 15 cm. Chelicerae of a black wishbone (Nemesiidae) spider, a mygalomorph Spiders occasionally bite humans. ... Species 27 species; see list of rattlesnake species and subspecies. ... Egyptian Cobra, Naga haje This article is about snakes. ... Species Over 65, see article. ... Types of chelicerae: jackknife (in green), scissor (in blue) and 3-segmented chelate (in red) The Chelicerae are mouth parts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata (horseshoe crabs), and Pycnogonida (sea spiders). ... Latrodectism is the clinical syndrome caused by a neurotoxic venom that can be injected by the bite of any spider that is a member of the spider genus Latrodectus, in the family Theridiidae. ... Antivenom (or antivenin, or antivenene) is a biological product used in the treatment of venomous bites or stings. ...

Improvements in plumbing have greatly reduced the incidence of bites and fatalities in areas where outdoor privies have been replaced by flush toilets. In Sweden there have been incidents with black widow spiders being found in cars imported from southern U.S.[1] Old cars standing unused are an attractive habitat for the spider.

There are a number of active components in the venom:

• Latrotoxins
• A number of smaller polypeptides - toxins interacting with cation channels which display spatial structure homology - which can affect the functioning of calcium, sodium, or potassium channels.
• Adenosine
• Guanosine
• Inosine
• 2,4,6-trihydroxypurine.

The venom is neurotoxic. [2] A latrotoxin is a variety of neurotoxin that stimulates motor and sensory neurons to release neurotransmitters. ... Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ... A cation is an ion with positive charge. ... Adenosine is a nucleoside composed of adenine attached to a ribose (ribofuranose) moiety via a β-N9-glycosidic bond. ... The chemical structure of Guanosine Guanosine is a nucleoside comprising guanine attached to a ribose (ribofuranose) ring via a β-N9-glycosidic bond. ... Inosine is a molecule (known as a nucleoside) that is formed when hypoxanthine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. ... A neurotoxin is a toxin that acts specifically on nerve cells – neurons – usually by interacting with membrane proteins such as ion channels. ...

Pharmaceutical applications

Research in Chile about increased virility resulting from Black Widow spider bites found spermicidal qualities associated with the venom, in addition to rumored priapism coupled with involuntary ejaculation. "Spider bitten" men anecdotally had "super virility" after recuperating from a spider bite. Priapism (Ancient Greek: ) is a potentially harmful medical condition in which the erect penis does not return to its flaccid state (despite the absence of both physical and psychological stimulation) within about four hours. ...

Researchers hope to be able to create a topical contraceptive and a marketable alternative to other virility treatments.^{[citation needed]}

Gallery

Female black widow from the upper rear, showing pattern. black widow, upper rear view Image copyleft: Image taken by me, released under GFDL Pollinator 03:59, Nov 9, 2004 (UTC) ( ) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...	Female black widow showing red "hourglass" marker. black widow from below Image copyleft: Image taken by me, released under GFDL Pollinator 03:57, Nov 9, 2004 (UTC) ( ) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...	Female black widow showing mouthparts. black widow, upper front view Image copyleft: Image taken by me, released under GFDL Pollinator 03:59, Nov 9, 2004 (UTC) ( ) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...	Dorsal view. Note that the red dot is formed by this spider's spinnerets. Wikipedia does not have an article with this exact name. ...
Black widow spider with its prey. Image File history File links Photograph by Patrick Edwin Moran of a Latrodectus mactans (black widow spider) eating an insect that she has wrapped in silk. ...	Immature female black widow - brownish coloring (darker close to the eyes) with yellowish markings Image File history File linksMetadata Download high-resolution version (2565x1710, 587 KB) [edit] Summary Immature female black widow spider Latrodectus hesperus 10 Sept 2006, Los Angeles, California, USA Original image/own work Matthew Field http://www. ...	A large mature female with a prominent red "hourglass" marking. Image File history File linksMetadata Black_Widow_11-06. ...	Black widow suspended in her web. Image File history File linksMetadata Size of this preview: 800 × 450 pixelsFull resolution (1600 × 900 pixel, file size: 193 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Black widow spider Metadata This file...
Female black widow feeding Image File history File links Metadata Size of this preview: 465 × 599 pixelsFull resolution (596 × 768 pixel, file size: 315 KB, MIME type: image/jpeg) Photo taken in California, USA. This female black widow is eating something that got ensnared in her web. ...

References

is the 290th day of the year (291st in leap years) in the Gregorian calendar. ... Also see: 2002 (number). ...

External links

Wikispecies has information related to:

Latrodectus mactans

Wikimedia Commons has media related to:

Latrodectus mactans

Wikimedia Commons has media related to:

Latrodectus hesperus

• Latrodectus Mactans on Pterodattilo
• Virginia Cooperative Extension: widow spiders
• University of Washington Burke Museum spider myths
• Bites and stings of medically important venomous spiders - UCR
• Pictures of L. mactans (free for noncommercial use)