November 17, 2008

Black Widow Spider (Latrodectus mactans )

Black Widow Spider (Latrodectus mactans)

Araneae: Theridiidae, Latrodectus mactans
Black Widow Spider (Latrodectus mactans )The black widow spider (Latrodectus) is noted for its neurotoxic venom. These venomous spiders are found in warm and temperate climates all around the world. They live in dark places, in drain pipes, under logs and rocks, etc in North America from Florida and California to southern Canada. Their bite rarely kills humans. There are three species commonly called black widow in North America: The southern black widow (Latrodectus mactans), the northern black widow (Latrodectus variolus), and the western black widow (Latrodectus hesperus).

Black Widow Spider (Latrodectus mactans )The male black widow’s abdomen is longer than that of the female, with white and red markings on its sides. The female’s abdomen is almost spherical, usually with a red hourglass mark below or with 2 transverse red marks separated by black. The legs of the male are much longer in proportion to his body than that of the female. The female is the most easily recognized, her shiny black body giving great contrast to the red hourglass marking on her round abdomen. Black Widow Spiders are extremely poisonous arachnids (not insects). Their venom is 15 times as poisonous as the venom of the prairie rattlesnake.

Black Widow Spider (Latrodectus mactans )The female black widow spider rarely leaves her web. The web she constructs is an irregular, tangled, cris-cross web of rather coarse silk. The core of the web is almost funnel shaped, woven into a silken tunnel in which the female spider spends the majority of her daylight hours. This web is altered and rebuilt in a regular basis and is capable of capturing rather large insects. The female wraps any captured prey with her silk, repeatedly turning her victim with her legs as she applies more silk. After her victim is covered in silk, the spider kills her prey by injecting her venom. The prey might be eaten immediately or reserved for a later feeding. After the prey is fed upon and the body fluids are sucked from the victim, the carcass is cut loose and allowed to drop to the ground. The female black widow is most often found hanging upside down in her web, where she spends most of her daytime hours. She stays close to her egg mass, defensively biting anything that disturbs her or her egg sac. After laying her eggs, the female black widow is hungry and more likely to bite a human. The female black widow stores sperm, producing more egg sacs without mating. Some females live more than three years.

Black Widow Spider (Latrodectus mactans)A sexually mature male spins a "sperm web", deposits semen on it, and charges his palpi with the sperm. The male then 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. The spiderlings or baby spiders are not poisonous but they are cannibals, eating each other. 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 Latrodectus mactans is the only black widow species for which this form of sexual cannibalism has been observed in the wild.

Black Widow Spider (Latrodectus mactans )Food: Black Widows eat flies, moths, crickets, small reptiles and other small animals. Their fangs inject venom and digestive juices into the prey. This kills the prey and also liquifies its flesh, letting the spider eat it easily.

Anatomy: Females (about 1 1/2 inches across) have a black body with a distinctive red hourglass shape on the underside of the abdomen. Males are smaller (about 3/4 inch across) with longer legs and red and yellow markings. The females are much more poisonous than the males. Black Widows have a two-part body, strong jaws, poisonous fangs, and a hard exoskeleton.

Webs: Black Widow Spiders use silk to make tangled-looking webs, usually near the ground in dark places. The tips of the spider's legs are oily; this oil keeps them from getting trapped in their own webs.

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6 comments:

Sang Penyamun said...

ada aktifitas seksual disini ya.. pantes dari tadi kepengen bgt mampir ke rumah putty..xixixixi..., itu laba laba gak ada di indonesia kan, jadi kita gak perlu khawatir deh ama gigitan nya.

Erik said...

Wah untung gak ada di Indonesia ya.

ferumx said...

tapi ok juga buat pengetahuan,sapa tau laba-labanya tertarik pindah habitat ke indonesia:-)

dnahdiar said...

mau tanya?
sebenarnya hewan paling mematikan apa black wido atau ular laut atau ada yang lain..........

SY said...

hey your blog is nicely written..

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AnakMuda said...

Ngeri....tatut.... :D hix..ix..