Theridiidae

Enoplognatha ovata

Chrysso.pulcherrima.male.-.tanikawa

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Coscinida.japonica.female.-.tanikawa

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Dipoena.martinae.female.-.tanikawa

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Enoplognatha.abrupta.female.-.tanikawa

Episinus.nubilus.male.-.tanikawa

Theridiidae, commonly known as cobweb spiders or comb-footed spiders, is a large family of arachnids that includes over 2,200 species in more than 100 genera. The family is well-known for its members' unique web-building behaviors and the diverse environments they inhabit, ranging from forests and deserts to human dwellings. One of the most famous members of this family is Latrodectus, the genus that includes the black widow spiders.

Characteristics

Members of the Theridiidae family are distinguished by their tangle webs, which are irregular, messy, and sticky. Unlike the orderly orb webs of Araneidae spiders, cobweb spiders create a three-dimensional space of silk threads to trap their prey. These spiders have a comb of serrated bristles, or setae, on their fourth pair of legs, which they use to fling silk over their prey, effectively immobilizing it.

The size and appearance of Theridiidae spiders can vary greatly. They typically have a globular abdomen and a relatively small cephalothorax. Coloration is species-dependent, ranging from dull to bright and sometimes mimicking other more dangerous species as a form of Batesian mimicry.

Behavior and Ecology

Theridiidae spiders are predominantly insectivorous, preying on insects and other small arthropods caught in their webs. Some larger species have been known to capture small vertebrates. Their silk is not only used for capturing prey but also for constructing egg sacs and as a means of locomotion in a behavior known as ballooning, where young spiders disperse by floating on the wind with silk threads.

These spiders exhibit a wide range of reproductive behaviors, including complex courtship rituals to avoid cannibalism, which is common in the family. Females often produce multiple egg sacs over their lifetime, which they fiercely protect.

Distribution

The Theridiidae family is cosmopolitan, with species found on every continent except Antarctica. Their adaptability to various climates and habitats, including human residences, contributes to their wide distribution.

Human Interaction

While most Theridiidae spiders are harmless to humans, a few, like the black widow spiders of the Latrodectus genus, possess venom potent enough to cause significant health issues in humans. Symptoms of a black widow bite may include pain, muscle rigidity, vomiting, and sweating. However, fatalities are rare, and effective treatments are available.

Despite the fear they often inspire, Theridiidae spiders play a beneficial role in controlling insect populations, including pests in homes and gardens.

Conservation

The conservation status of Theridiidae species varies widely. While many species are common and not of concern, others are threatened by habitat loss, pollution, and climate change. Efforts to conserve arachnid habitats are crucial for the protection of these diverse and ecologically important creatures.