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:For the Chechen rebel group see Black Widows.
The black widow spider (Latrodectus mactans) is notorious for its neurotoxic venomThis article is about the toxin. For other meanings, see Venom (disambiguation Venom is a general term for the toxins used by several groups of animal species, for the purpose of defense and hunting prey. Most widely known are snakes, some species of whic. It is a large widow spiderThe scientific term for the widow spider is a member of the spider genus Latrodectus . The majority of the Latrodectus genus in and of itself breaks down taxonomically into approximately 31 recognized species, with the family Theridiidae (black widow spid found throughout the world and commonly associated with urban habitats or agricultural areas. Although the common name 'black widow spider' is used to refer specifically to L. mactans it is occasionally also applied to several members of the Latrodectus (widow spider) genus in which there are 31 recognised speciesThis article discusses biological species. Also see combinatorial species for the mathematical meaning of the term. Species is also a movie by Roger Donaldson. In English "species" is both singular and plural. The word " specie" is unrelated and is used t including the Australian red-backThe red-back spider Lactrodectus hasselti is a potentially dangerous spider now found throughout Australia. Its origins are uncertain, and it may have been spread by human activities during the 19th century. Red-back spiders are now found in all but the m and brown widow spider .
Adult black widow spiders are shiny black with a reddish hourglass shape marking on the bottom of its abdomen. Female black widow spiders are about 1.5 inches (40 mm) with legs spread. Without its legs, they are about 0.5 inches (10 mm). Male black widow spiders are half the size of the female, but with longer legs.
Though its venom is toxic, deaths from Latrodectus bites are rare, only sixty-three having been reported in the United States between 1950 and 1959 (Miller, 1992). Black widow venom acts by causing a localized release of the neurotransmitterA neurotransmitter is a type of molecule that carries signals between neurons (nerve cells) at synapses in the nervous system. Neurotransmitters may be either excitatory ( EPSPs) or inhibitory ( IPSPs). That is, they may foster the initiation of a nerve i acetylcholineThe chemical compound acetylcholine often abbreviated as ACh was the first neurotransmitter to be identified. It is a chemical transmitter in the central nervous system (CNS) as well as in the parasympathetic nervous system in many organisms including hum, which is involved in muscular contraction. A bite results in a severe, uncontrollable, and prolonged muscle contraction in the area of the bite.
According to a widely-reported media story (Wigmore, 2003), Chilean scientists were using part of Latrodectus venom to synthesize a drug that will not only serve as a male contraceptive, but will also work in a fashion similar to Viagra; however, this has not been reported in any mainstream peer-reviewed scientific journal.
Black widow spiders live in temperate and tropical zones (McCorkle, 2002). They typically prey on a variety of insects, but occasionally they do feed upon wood lice, diplopods, chilopods and other arachnids (McCorkle, 2002). When the prey is entangled by the web, L. mactans quickly comes out of its retreat, punctures and poisons its prey (Foelix, 1982). The poison takes about 10 minutes to take effect, meanwhile the prey is held tight by the spider (Foelix, 1982). When movements of the prey cease, digestive enzymes are released into the wound (Foelix, 1982). The black widow spider then carries its prey back to its retreat before feeding (Foelix, 1982).
As characterized by arthropods, black widow spiders have a hard exoskeleton composed of chitin and protein (5). When a male is mature, he spins a sperm web, deposits semen on it, and charges his palpi with the sperm (3). Black widow spiders reproduce sexually where the male inserts his palpus into the female's spermathecal openings (3). The females often kill and eat the male after mating; however, some males do escape under circumstances where the female is already well-fed (1). The female lays eggs onto a web where they are camouflaged and guarded (3). A female black widow spider can produce nine egg sacs in one summer, each containing about 400 eggs (1). Usually, eggs incubate for 20-30 days, but more than 12 rarely survive through this process, due to cannibalism (1). It takes two to four months for black widow spiders to mature. The female live on for 180 days after maturing, while a male only lives on for another 90 days (1).
