Reproduction
Reproduction in black widow spiders is very interesting and unique. Female spiders are just like other egg-laying vertebrates. They have a pair of ovaries and an abdominal passage that delivers eggs to the exterior of the spider. This acts like the uterus of a vertebrate. Females have spermatical openings in which sperm is carried to the uterine tube via the insemination ducts. Females also have sperm storage that can store all the sperm she will need to fertilize eggs.[1]
Males first spin a small 'sperm web', in which they put a small amount of semen on. "He then charges his palps, or his sexual organs, with the sperm, abandons his habitat, and spends considerable effort to locate a female of his species."[2] After the male finds a female, he starts courtship. He vibrates the females web to make sure she is the right species, to let her know he is a mate and to make her open to mating. Mating occurs after the male inserts his papal organs into the females spermathical openings. After, spermatozoa, or male gametes that fertilize the ovum, are released onto the egg. The eggs are laid in a small web completely surrounded by a sac or cocoon that is in the shape of a pear. This egg cocoon is then guarded by the female. Within
the egg sac, the eggs hatch and spiderlings come out.[3]
1
http://www.findaspider.org.au/info/Reproduction.htm
2 http://animaldiversity.ummz.umich.edu/accounts/Latrodectus_mactans/
3 http://www.buzzle.com/articles/black-widow-spiders.html
the egg sac, the eggs hatch and spiderlings come out.[3]
1
http://www.findaspider.org.au/info/Reproduction.htm
2 http://animaldiversity.ummz.umich.edu/accounts/Latrodectus_mactans/
3 http://www.buzzle.com/articles/black-widow-spiders.html
Development
A female can produce four to nine egg sacs containing about 400 eggs in one summer. The eggs incubate for about twenty five days. Because black widow spiders are R strategist, few eggs survive and become adult spiders. It takes two to four months for the spiders to reach sexual maturity, but it takes six to nine moths for spiders to reach full maturity. [4] The female lifespan can be five years, but it is shorter for males. There is very little parenting.
When the spiderlings do leave the nesting sites, they do it by ballooning. This "is accomplished by crawling up grass blades, stems, or other upright objects on windy days and extruding strands of silk from their silk glands. As the wind catches these strands, the young spiders are lifted into the air and deposited at some distant point."[5] From there, they repeat this same life cycle.
4 http://en.wikipedia.org/wiki/Latrodectus_mactans
5 http://msucares.com/pubs/publications/p2154.pdf
4 http://en.wikipedia.org/wiki/Latrodectus_mactans
5 http://msucares.com/pubs/publications/p2154.pdf