Black widow spider

:For other uses of the name "Black Widow", see Black Widow.

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The black widow spider (Latrodectus mactans) 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 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 species including the Australian red-back and brown widow spider. In South Africa, the black widow is also known as the button spider.

Related Topics:
Spider - Neurotoxic - Venom - Widow spider - Latrodectus - Species - Red-back - Brown widow spider

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Adult female black widow spiders are shiny black with an hourglass shape marking on the bottom of its abdomen which, although most commonly red, may range in color from white to yellow to various shades of orange and red. In some varieties, the two halves of the hourglass shape may be separated into two separate dots. Female black widow spiders are about 1.5 inches (38 mm) counting legspan. The body is about 0.5 inches (13 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 yellow stripes and a yellow hourglass mark. Juvenile black widow spiders are usually brown with yellow stripes and a yellow 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.

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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 woodlice, diplopods, chilopods and other arachnids (McCorkle, 2002). 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 poisons its prey (Foelix, 1982). The poison takes about ten minutes to take effect, meanwhile the prey is held tightly 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).

Related Topics:
Woodlice - Diplopods - Chilopods - Arachnids

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As is characteristic of all 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 when 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 wherein the female is already well-fed (1). The female deposits her eggs in a globular silken container which they remain 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 twenty to thirty days, but rarely do more than twelve 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 ninety days (1).

Related Topics:
Arthropod - Chitin - Protein - Palpi - Cannibalism

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