Theridiidae

Common Name

Cobweb Spiders, Comb-Footed Spiders

Overview

Theridiidae is a large family comprising over 2,200 described species of spiders. Members of this family are known for their irregular, sticky webs, which are often referred to as cobwebs. These spiders are found in various habitats around the world, ranging from forests and grasslands to human habitations.

Taxonomy

Key Characteristics

  • Web Structure : Irregular, sticky, and tangled webs known as cobwebs.
  • Size : Typically small, ranging from 1 to 12 mm in body length.
  • Body Shape : Rounded abdomen and relatively long legs.
  • Coloration : Varies widely, with some species displaying bright colors and intricate patterns, while others are more drab and muted.

Life Cycle

Theridiidae spiders undergo incomplete metamorphosis. The life cycle has the following stages:

  1. Egg : Laid in silk egg sacs.
  2. Spiderling : Hatch from eggs; look like miniature adults.
  3. Juvenile : Goes through several molts before reaching maturity.
  4. Adult : Capable of reproduction, typically lives for around a year.

Behavior and Ecology

  • Web-Building : Construct irregular, three-dimensional webs in which they capture prey.
  • Diet : Mostly insectivorous, feeding on a variety of insects and other small arthropods.
  • Defense : Some species, like the infamous black widow spiders, possess venom that can be harmful to humans. Most, however, are harmless and shy.

Notable Species

  • Latrodectus mactans : The Southern Black Widow, known for its potent venom and distinctive red hourglass marking.
  • Steatoda grossa : The False Widow, often mistaken for the more venomous black widow.
  • Theridion grallator : The Hawaiian Happy-Face Spider, famous for the unique patterns on its abdomen.

Conservation

Most species within Theridiidae are not currently considered endangered. However, habitat destruction and pollution could potentially impact local populations. Conservation efforts typically focus on preserving natural habitats and reducing pesticide use.

Significance to Humans

  • Medical : Some species, such as Latrodectus (black widows), can deliver medically significant bites, requiring attention.
  • Pest Control : Beneficial in controlling insect populations.
  • Scientific : The adaptable nature and varying venom properties of Theridiidae make them subjects of numerous studies.

Fun Facts

  • Some Theridiidae spiders engage in kleptoparasitism, stealing prey from other spiders' webs.
  • The silk produced by cobweb spiders can be up to five times stronger than steel of the same diameter.
  • Latrodectus species are often cited in folklore and mythology due to their venomous nature.
  • Some cobweb spiders can survive for months without food.