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Spider web

life science Maturity 9-11 Next article →

A spider web is a complex structure made of proteinaceous silk. Spiders extrude this silk from specialized organs called spinnerets. Most spiders build these structures to capture prey, such as insects, for food.

A classic circular form spider's web
A classic circular form spider's web

While many people use the term "spider web" for a clean, active structure, the term "cobweb" often refers to an abandoned, dusty web. Biologists also use "cobweb" to describe the tangled, three-dimensional webs of the family Theridiidae. These spiders are also known as tangle-web or comb-footed spiders.

Spider silk production began when archaic spiders moved from water to land during the Early Devonian period. Initially, they used silk to protect their bodies and eggs. Over time, spiders evolved to use silk for hunting. This transition involved using silk for guide lines, then ground webs, and finally the aerial webs we see today. Silk is produced in glands located at the tip of the spider's abdomen. Each gland produces a specific type of thread for a specific task. Some spiders can produce up to eight different types of silk. These include sticky silk for trapping prey and fine silk for wrapping it.

Spider holding on to its prey
Spider holding on to its prey

Constructing a web is an energetically expensive process because silk requires large amounts of protein. To offset this cost, many spiders eat their own webs daily. This allows them to recycle the silk proteins through ingestion and digestion. Once a web is built, it becomes an efficient tool for gathering food. It allows the spider to catch prey without the energy spent running it down. Spiders can navigate their own webs using dense hairs and nonstick coatings on their feet. They also use specific non-sticky silk strands to move safely across the structure.

Orb web building steps-01
Orb web building steps-01

The construction of a classic orb web follows a very precise sequence. First, the spider releases a fine adhesive thread to drift on a breeze across a gap. When the thread sticks to a surface, the spider feels the vibration and reels it in. The spider then walks along this line to strengthen it with a second thread. After this, it builds a Y-shaped netting using radial lines. The spider continues adding radials until the web is complete. The number of radials depends on the size of the spider and the web. Often, a web is about 20 times the size of the spider.

The spider uses its own body as a measuring tool during construction. It creates a spiral of non-sticky, widely spaced threads to move around easily. The distance between these initial spirals is proportional to the distance from the spider's back legs to its spinnerets. Once the frame is set, the spider replaces the non-sticky spiral with a closely spaced, adhesive spiral. It works from the outside of the web toward the center. After finishing, the spider often sits near the hub, sometimes facing downwards, to wait for vibrations.

Argiope sp
Argiope sp

There are many distinct types of webs found in nature. Orb webs are usually built in a vertical plane by families like Araneidae. Sheet webs are built in a horizontal plane. Other variations include funnel webs, tubular webs that run along trees, and tangle webs. Some spiders, like the net-casting spider, use a small net attached to their front legs to lunge at prey. This method saves energy compared to active hunting. Other spiders use silk to catch the wind and sail to new locations. Even water-dwelling spiders use silk, such as the diving bell spider, which uses a web to trap air underwater.

In the Web
In the Web

Humans have interacted with spider webs for centuries in surprising ways. In ancient Greece and Rome, cobwebs were used as medical dressings for wounds. This worked because silk is rich in vitamin K, which is essential for blood clotting. In the 16th century, artists in the Austrian Tyrolean Alps created "cobweb paintings" by applying watercolor to layered webs. In Nigeria, spider webs are used in traditional xylophones to create a buzzing sound. Today, scientists study the incredible strength of spider silk. They hope to develop new, super-tough materials based on these biological properties.

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🖼️ Images & Media (9)
File:A classic circular form spider's web.jpg
A classic circular form spider's web.jpg
File:Orb web building steps-01.svg
Orb web building steps-01.svg
File:Spider holding on to its prey.JPG
Spider holding on to its prey.JPG
File:Argiope sp.jpg
Argiope sp.jpg
Larinioides cornutus building a web,...
File:In the Web.jpg
In the Web.jpg
File:Trees cocooned in spiders webs.jpg
Trees cocooned in spiders webs.jpg
File:Tawakoni spider-web 2622.jpg
Tawakoni spider-web 2622.jpg
File:Arabella web aboard second Skylab mission (cropped).jpg
Arabella web aboard second Skylab mission...
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