Understanding Spider Webs and Cobwebs
Spiders produce webs, but “cobweb” refers to a specific condition of a web, not a distinct type spun by a particular spider. A cobweb is typically an old, neglected, dusty web found in undisturbed areas.
Understanding Cobwebs Versus Fresh Webs
A fresh spider web is an active, functional structure, designed for immediate use. These webs are sticky and regularly maintained. In contrast, a cobweb is an abandoned spider web that has accumulated dust and debris. While “cobweb” can also refer to the tangled, three-dimensional webs built by spiders in the family Theridiidae, its common usage describes the state of an old web.
Many spiders produce webs that become cobwebs, a descriptive term for a web’s state. Once abandoned, the silk collects particles like dust and pet hair, making it visible and giving it the characteristic appearance of a cobweb.
The Process of Spider Web Construction
Spiders create webs using silk, a protein-based fiber produced in specialized silk glands within their abdomen. Liquid silk is extruded through spigots on the spider’s spinnerets. Spiders manipulate these spinnerets and use their legs to pull the silk, solidifying it into a thread.
Web construction begins with the spider releasing a silk thread carried by wind until it adheres to a surface. The spider reinforces this thread, forming a foundational bridge. From this framework, radial lines, or spokes, extend from a central hub to the outer edges. A sticky spiral is then laid down to ensnare prey.
Spider silk possesses remarkable properties, including toughness and elasticity. It is stronger than steel of the same diameter and more elastic than rubber, allowing it to absorb significant impact without breaking. Spiders can produce several different types of silk, each with unique properties suited for specific parts of the web or other functions.
Diverse Functions of Spider Webs
Spider webs serve multiple purposes beyond just catching food. The primary function for many web-building spiders is to trap insects, which form their main diet. The sticky, intricate design of the web acts as an effective snare, capturing unsuspecting prey. Spiders sense vibrations in the web to detect trapped prey, allowing them to locate and retrieve their meal.
Webs also provide shelter and protection for spiders from predators. Some spiders use silk to construct retreats or nests where they can hide. Additionally, silk is used to protect egg sacs, ensuring the safety of their offspring. Male spiders may also create specialized “sperm webs” as part of their mating rituals. Silk is even used for dispersal, with young spiders employing a technique called “ballooning,” where they release silk threads to be carried by air currents, allowing them to travel long distances to new locations.
The Transformation of Webs into Cobwebs
A functional spider web eventually becomes a cobweb through a natural process of deterioration and abandonment. Spiders often leave their webs for various reasons, such as damage to the web, a lack of prey in the area, or simply moving to a new, more advantageous location. Building a web is an energy-intensive process, but spiders may choose to build a new one if the current web is no longer efficient or safe.
Once a web is abandoned, it is no longer maintained or cleaned by the spider. The sticky properties of the silk, which are so effective at trapping prey, also make it an ideal surface for collecting airborne dust, dirt, pollen, and other small particles. As these particles accumulate, the web loses its transparency and stickiness, becoming visible and often tangled. This dusty, disused structure is what is commonly recognized as a cobweb.