Spiders do not construct “nests” in the way birds do for communal living or raising young. Instead, these arachnids are skilled engineers, creating a variety of intricate structures for their survival. These structures serve diverse purposes, ranging from capturing prey to providing shelter and protecting their offspring. This article explores the various structures spiders build and their functions.
Spider Silk: The Master Material
Spider silk is a protein-based fiber produced by specialized glands within a spider’s abdomen and extruded through spinnerets, located at the rear of the abdomen. This material is known for its properties, including impressive strength, elasticity, and adaptability. For instance, dragline silk, used for safety lines and as structural elements in webs, can be five times stronger than steel of comparable diameter and can stretch up to five times its original length without breaking.
Spiders can produce up to seven different types of silk, each with unique characteristics tailored for specific functions. Beyond the robust dragline silk, other types include sticky capture silk for ensnaring prey in webs, soft silk for creating protective egg sacs, and strong silk used for structural support in various constructions. The versatility of silk makes it the fundamental building block for nearly all spider-made structures, facilitating diverse behaviors from hunting to reproduction.
Beyond the Web: Spider Structures and Their Uses
Spiders create a wide array of structures, each designed for a particular purpose. Many spiders construct elaborate hunting structures to capture prey. Orb webs, for example, are classic circular designs with sticky spiral threads that efficiently trap flying insects. Other hunting webs include funnel webs, which lead to a retreat for ambushing prey, and irregular tangle webs, which disorient and trap insects. Sheet webs are flat, often messy, and entangle prey.
Beyond hunting, spiders build various structures for shelter. Many species construct silken retreats, which are compact enclosures providing protection from predators, adverse weather, or for molting. Some spiders, like tarantulas, line their burrows with silk to reinforce the walls and create a more secure home. These silken linings can also help maintain humidity within the burrow, creating a stable microenvironment.
Spiders also build reproductive structures. Female spiders weave specialized silk sacs to protect their eggs. These egg sacs vary in appearance and can contain dozens to hundreds of eggs, depending on the spider species. Some spiders carry their egg sacs with them, while others attach them to a substrate or suspend them within a web, providing a secure nursery until spiderlings emerge.
How Spiders Build Their Structures
Building these intricate structures involves precise techniques and an understanding of material properties. Spiders extrude liquid silk from their spinnerets, which hardens into a fiber upon contact with air. They manipulate these threads with their legs, often using their third claw for silk handling, and can utilize environmental factors like wind to initiate construction.
Building an orb web typically begins with the spider releasing a “bridge line” that drifts until it attaches to a distant surface. Once this initial line is secure, the spider reinforces it and then creates a “Y”-shaped foundation. From this framework, non-sticky radial lines are laid out, forming the spokes of the wheel. Finally, a sticky spiral is woven between these radii, often involving a temporary non-sticky spiral as a guide, later removed or consumed as the final capture spiral is laid down.
For structures like burrow linings, spiders apply silk to the interior walls, reinforcing the soil and creating a smooth, protective layer. This silk can also act as a sensory network, transmitting vibrations from outside the burrow. Egg sac construction involves the female spider laying a silk pad, depositing eggs, and then wrapping them within multiple silk layers, forming a spherical or disk-shaped protective cocoon. This weaving ensures the eggs are cushioned and shielded from external threats.