Sheet-Weavers (Linyphiidae)

Linyphiidae comprise nearly 5000 species worldwide, making them the second most common spider family after the jumping spiders. They are web-building spiders with a body length of 1–8 mm (although most species are only 1–3 mm), which are recognizable by their horizontal sheet webs. Ground-dwelling linyphiids build their tiny sheet webs in crevices in the ground, which can be seen early in the morning with dew covering the silk. Aerial webs built by spiders in this family often consist of a horizontal or dome-shaped web sheet, frequently called the canopy due to the way it curves downward at the peripheries. In some species, the web sheet is shaped more like a cup or container; these webs are often referred to as “bowl and doily” webs because of their shape. With a system of suspension and alarm threads, the web sheet is held under tension both above and below and is anchored to the vegetation. Contact with these threads causes approaching animals to create vibrations, which are transmitted to the web sheet. The spider thus receives information about whether it is a potential prey or a predator, allowing it to react accordingly: attack or escape. The eight small eyes, on the other hand, do not facilitate visual orientation (Fig. 4.22).