How Orb Weaver Spiders Spin Intricate Webs Every Day

Spring is the time when many spiders emerge from their winter hiding places and start doing what they do best: spinning webs. This is when you may spot the classic cobwebs in your yard or garden. Before you sweep them away as part of your spring cleaning, spare a thought for the creature that went to all the effort to create them. Here we will explain exactly how orb-weaver spiders make their webs and why they are architectural wonders.

Why Orb Weavers Are Special Spiders

Orb-weaver spiders are members of the Araneidae family of spiders. They are found in all parts of the world except the Arctic and Antarctica, and there are thousands of different species. In North America alone, there are approximately 180 different orb-weaver species, including the garden orb weaver and the spiny orb weaver. Most spiders have two claws on each foot, but orb weavers have an extra claw that helps them create such amazing and complex webs. These intricate designs use the minimum amount of silk so the spider expends the least amount of energy.

What Is Spider Silk?

Spider silk is one of the most incredible biomaterials on Earth. If you compare it weight-for-weight with other materials, it has a higher tensile strength than steel and can match rubber for elasticity. It is made from proteins and is especially rich in glycine and alanine amino acids.

Spiders have special silk-making organs called spinnerets on their abdomens. Each has a tiny nozzle that produces one filament of silk. However, spiders have many spinnerets, so they produce several filaments of silk that combine like a cable. Spiders can also control the thickness of the filament by using muscles to either slow down or speed up the silk as it comes out. Spiders can continually produce silk as long as they are well-nourished and healthy, since silk production depends on their protein intake.

Orb Weaver Webs

The webs constructed by orb weavers are the classic circular webs that we most often associate with garden spiders. They look a little like a round fishing net, and their purpose is to catch prey. The plan is for flying insects to inadvertently fly into the web, get stuck, and become the orb weaver’s next meal. For this plan to work, the web must be strong but also sticky so that the insect does not escape. This requires different types of silk and some very clever weaving.

How Orb Webs Are Constructed

The exact design of orb webs varies with the species of spider. However, they all start with a bridge line. This may be shot into the air to catch the breeze and snag onto another support. Alternatively, the spider fixes the line to one support (such as a twig), then, as it trails silk, it walks down to the ground and back up another twig, where it stops, pulls the line tight, and fixes it. Further strands are added to strengthen the bridge. Next, it creates a Y-shaped structure with the central hub of the web at the point where the three spokes of the Y meet.

At this point in the project, a series of mini-triangles are created (this is the framing phase), and many more spokes are added. These spiders are able to measure the distances between the spokes with their legs so that they can fill in any large gaps. They keep the hub central by constantly testing the tension in all the spokes. Once this is complete, the strengthening spiral can be laid down.

Why Are Webs Sticky?

Once all the structural elements are complete, the spider will lay down the ‘capture thread’, which is sticky, elastic, and strong. It includes microscopic droplets of highly entangled polymers that make it a bit like chewing gum. Cribellate orb weavers, such as the Uloboridae spiders, however, do things a bit differently. They make their webs out of a woolly silk (called cribellate) which has velcro-like strands in which the insect’s legs and bristles get stuck.

How Long Does It Take to Spin a Web?

It typically takes about 30 to 60 minutes for an orb-weaver spider to complete its web, though some species may take longer. Because spider silk is antimicrobial, it can last for some time as it will not rot very quickly. However, orb webs are frequently damaged by larger animals. While it is thought that the zig-zag pattern on webs (the stabilimentum) is designed to prevent birds from flying into the web, it would not deter a deer racing through a forest. Also, pollen and dust get stuck in it, which renders the sticky elements ineffective.

Some spiders carry out repairs to broken webs, but many start a new one every day. This means they can produce hundreds of webs over their lifetime. Some eat their webs to recycle the protein, but others abandon them and just start again in another location.

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