Theridiosomatidae

Common Name

Ray Spiders

Overview

The family Theridiosomatidae, commonly known as ray spiders, is a group of small orb-weaving spiders found in various parts of the world. These spiders are characterized by their unique web structure and specific behavioral traits that make them fascinating subjects of study.

Taxonomy

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Arachnida
  • Order: Araneae
  • Suborder: Araneomorphae
  • Family: Theridiosomatidae

Key Characteristics

  • Small size, typically less than 3 mm in length
  • Globular abdomen
  • Metallic sheen on some species
  • Unique web structure with radial lines and anchor lines that create a cone-shaped retreat
  • Scopulated (brush-like) hairs on legs for web construction

Life Cycle

  • Egg Stage: Eggs are laid in silken sacs attached to vegetation.
  • Spiderling Stage: Spiderlings emerge and disperse via silk threads.
  • Juvenile Stage: Undergo multiple molts as they grow.
  • Adult Stage: Construct webs, mate, and reproduce.

Behavior and Ecology

  • Construct conical orb webs in moist, shaded habitats
  • Display a characteristic “plucking” behavior when vibrating their webs for prey capture
  • Primarily insectivorous, feeding on small insects and other arthropods
  • Found in both forested and riparian environments

Notable Species

  • Theridiosoma gemmosum: A widely studied species known for its metallic abdominal sheen.
  • Ogulnius obtectus: Another notable species with distinct web construction.

Conservation

Currently, no species within Theridiosomatidae are listed as endangered. However, habitat destruction could impact populations, as these spiders rely on specific environmental conditions for survival.

Significance to Humans

Ray spiders are not harmful to humans and play a beneficial role in controlling insect populations. Their unique web-building techniques also provide insights into the diversity of spider silk engineering.

Fun Facts

  • Ray spiders get their name from the radial, spoke-like structure of their webs.
  • Some species exhibit iridescence, giving them a metallic appearance.
  • Unlike many orb-weaving spiders, ray spiders construct webs horizontally.
  • Their web-plucking behavior is a unique method to immobilize trapped prey.
  • These spiders can adjust their web architecture based on environmental conditions.