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Social Spiders

Users visiting Sibon recently will have noticed the large social spider nest/web in the marula tree above the gazebo area. In South Africa the social spider Stegodyphus mimosarum occurs in the eastern parts. 

They are small brown grey spiders with dark facial markings. Females are larger than males.

Social spiders are interesting because there are several advantages to living in a colony:

  • Egg and spiderling care is shared.
  • Web maintenance is shared.
  • Capture of prey is a community effort.
  • Larger prey than that for a single spider can be caught.
  • Food is shared.
  • Nest defense is shared

Nests are naturally constructed (mostly) in thorn trees in the Lowveld, but artificial aids such as posts and fences are also used. A nest may be initiated by as few as two spiders. Migration is initially by females who start a new colony. Nests are occupied for several years by successive generations. Birds utilize the silk for nest lining. 

Within the colony body size and condition determines what function individual spiders have. Smaller spiders attend to web maintenance while larger spiders secure food. Those with poorer body condition attend to foraging.

Globally there are approximately 39000 known spider species. The majority of spiders prefer solitary lives outside of mating. Where spiderlings eat their parents it is known as matriphagy. 

A dozen more interesting facts about spiders: 

  • Spiders have special glands that produce silk used for making webs.
  • Spiders don't occur in the Antarctica.
  • Spiders molt.
  • The anterior part of the body is known as the cephalothorax.
  • The posterior part of the body is known as the abdomen.
  • Only one spider family, Uloboridae, does not have venom.
  • Some spiders to not spin webs to catch prey.
  • Some female spiders eat their mates. 
  • Spiders turn their prey into a liquid form before ingestion.
  • Special enzymes are used to liquidize their prey.
  • The largest spiders are able to catch birds.
  • Female spiders encase their eggs in a bed of silk, known as an egg sac.

 

Facts researched on the Internet, text by John Llewellyn.