Spider silk is one of the strongest materials in the natural world. Consisting almost entirely of large proteins, silk fibres have tensile strengths comparable to steel

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and, on a weight to weight basis, some silks are nearly as elastic as rubber. In combining these two properties, silks reveal a toughness that is two to three times that of synthetic fibres like Nylon or Kevlar. Spider silk is also anti-microbial, hypoallergenic and completely biodegradable.

Some spiders can produce more than one type of silk. A common orb-web spider, for example, may contain at least four different kinds, each adding a different component, such as strength, flexibility, and stickiness.

How is spider silk made? It starts in one of the silk glands called the ampulate gland. The silk itself consists of so-called spidroins (large proteins) which are created in this gland. When a spider wants to make silk it converts these proteins into a solid fibre in a tiny fraction of a second. Most spiders have many glands, each making a single fibre, and as the threads of silk emerge through narrow spigots they are spun together in the organ known as its spinneret.

While in the ampulate gland, the spidroins are stored in a gel state prior to use. As the gland narrows down into a duct this gel is then turned into silk fibre. These proteins have a disorganised structure while in a highly concentrated gel state and dissolved in water but when they are converted to silk, the structure changes and becomes immensely stable. This transformation occurs with mounting carbon dioxide pressure and a corresponding decrease in pH values along the duct. When the spidroid proteins are pressed down into the acidic environment in the duct, the proteins begin to bind and “unfold” to create silk fibre. That’s amazing as it is, but spiders have the capacity to do this instantaneously for prolonged periods.

One gland makes strong silk for the web’s outer rim and spokes, as well as for an anchoring lifeline. Another gland produces different silk to wrap and secure freshly captured prey, whilst yet another produces egg cocoon silk used for protective egg sacs. A fourth produces a silk glue comprising sticky globules and a fifth manufactures silk that is used to form bonds between separate threads on attachment points.

All of these silk-producing glands need to function at the same time for the spider to eat and reproduce. The chances of a spider evolving just one of these silk glands is astronomical. To evolve all five of them approaches the impossible.

Slingshot silk

One type of spider constructs tension-loaded tools with all the aplomb of medieval engineers. These are triangle weaver spiders found in the US and many other parts of the world. After building a triangle-shaped web, they anchor themselves to a twig with silk from their abdomen and pull on a central anchor line, stretching the structure tighter and tighter.

This loads their web with potential energy like a crossbow string, but one in which their bodies are the release mechanism that holds the whole system taut until it’s time to fire. When a bug bumps into the web, the spider lets go of its anchor line and releases slack from its abdomen, catapulting its web (and itself) forward and capturing the bug.

A new study using high-speed cameras has revealed these webs store and release a staggering amount of energy. In fact, this web slinging can reach accelerations in excess of 770 metres per second squared, or about 26 times the maximum acceleration of a NASA space shuttle.

Balloon silk

Spiders can travel many hundreds of miles through the air by releasing silk and floating away. Researchers had thought that ballooning behaviour required drag forces from wind or thermals. Now, researchers reporting in the journal Current Biology show that electric fields at strengths found in nature not only trigger ballooning, but also provide lift, even in the absence of any air movement.

Every day, around 40,000 thunderstorms crackle around the world, collectively turning Earth’s atmosphere into a giant electrical circuit. The upper reaches of the atmosphere have a positive charge, and the planet’s surface has a negative charge. Even on sunny days with cloudless skies, the air carries a voltage of around 100 volts for every metre above the ground. In foggy or stormy conditions, that gradient might increase to tens of thousands of volts per metre.

The attraction between these two elements creates an electric field and it is this field that allows spiders to fly using a remarkable behaviour called ballooning.

It typically begins at places where the electric field is strongest, namely on the top of plants. The spider first drops a silk anchor to secure itself. Then it raises its two front legs in the air and uses special fine hairs called trichobothrium hairs to sense wind and electrical conditions—much like a built-in weather station. If the conditions are right, the spider then tiptoes on its back legs, raises its abdomen and releases silk strands into the air.

The silk strands are charged, which causes them to repel away from each other to prevent tangling. This form of static electricity is just like what happens to your hair after rubbing it with a balloon. Now ready to set sail, the spider breaks off its anchor line and lifts into the air using the force it gains from the electric field and the wind. Once airborne, it is thought that the spiders use their legs to balance or control speed.

Ballooning can take spiders on remarkable journeys, up to five kilometres in altitude and hundreds of kilometres in distance. In fact, spiders are often among the first species to colonise new volcanic islands or areas ravaged by natural disasters.

Plucking strings

Just like busking musicians, spiders, too, pluck their strings to find food and potential mates. A research team (from the universities of Oxford, Sheffield and Strathclyde) studying the way spider webs vibrate has discovered that spider silk can ring in a greater range of tones than most materials. Spiders use these vibrations to determine whether they’ve caught a meal, are being approached by a mate, or if they need to make web repairs.

It is known that spiders interpret vibrations with organs on their legs called slit sensillae, which are small, hypersensitive grooves that deform with even the slightest disturbance. When a fly hits a web, spiders will pluck the individual strings that are carrying information from the wriggling insect to interpret the data flowing through the silk.

By plucking the silk like a guitar string and listening to the ‘echoes’ the spider can also assess the condition of its web. When building a web from their disparate silk-producing sacs the spider has to ensure that the tension across the web is just right. Too much tension will mean that the prey will either fly through the web or bounce off the web, a phenomenon known as the ‘trampoline effect.’

At whatever level we examine spider silk we see evidence of forethought and design. At every level we see spectacular order and unfathomable intricacy in structure from the nano scale to the macro scale. As the Apostle Paul put it, God’s eternal power and Godhead are clearly seen “by the things that are made.” On that basis alone mankind is “without excuse” (Rom 1:20).