Unravelling the web

 
 

Comparing spiders to lions and webs to their dynasties, Caitríona Farrell investigates the science behind spinning a web

Perhaps you’re an arachnophobe, a Spiderman fanatic, or maybe you just want your own Spiderpig. Whichever category you fall into, it’s impossible to deny how phenomenal the spider web is as a natural structure. Spiderwebs are a place where insects become pasted to what resembles a distorted dartboard. Its strands merge to create, in this confined habitat, a unique food web. The glistening threads sparkle as if cutlery is set: the spider’s home is, in essence, a 24- hour fast food restaurant. It’s also where nature has recently linked arms with technology, in its remarkable attempt to mimic the biological structure.

Spider silks contain outstanding mechanical properties, with those of the Black Widow topping the poll, designating her status comparable to that of the queen bee, monarch of her beehive. This serves as a means of differentiating spider from spider in the arachnid kingdom, attaining status based on the silk they fabricate. The Black Widow’s spindles of spider web are extremely versatile; for instance, her dragline silk can be used as a fuel to store energy.

The silver glittery lining of a web is a thermal sheet, absorbing radiation, but things get even more heated when passers-by become stitched to this patchwork design. No mercy, and no silver lining is apparent for these poor creatures, victims to this net of sticky residue and stores of energy.

In nature, the glue-like gossamer that spiders use to form webs is secreted from the creature’s silk glands, transported to the spinneret through a duct where the arrangement takes shape. The spider then squirts out a thick gel of a silk solution before using their hind legs, body weight and centre of gravity to fashion their consistent design by elongating the gel into long threads. Spinning thread-like filaments and riding in air currents (a process called “ballooning”), they can extend the threads in an orderly manner. Essentially, the spinning of spider silk is the process of morphing a liquid thread into a solid. However, the explicit details of the process are still mysteriously unknown.

But there may be more than just natural interest to the Black Widow’s dragline silk. Its properties have been carefully studied in the synthetic manufacturing world and its applications could extend to the construction of lightweight, super-strong body armour. There have also been reasonable developments in medical technologies – researchers have already filed patents after identifying the two proteins, MaSp1 and MaSp2, that compose dragline silk. As a result it has emerged that these scientists have completely cracked the web’s genetic code. Production of this protein could be carried out by inserting the correct genetic data into a host, such as bacteria. Nevertheless, the challenge lies in the spinning of the silk. There are many artificial spinning techniques that could be viable; it’s just a matter of experimentation to identify the most efficient type.

Nothing to date has been manufactured to be as efficient as the natural dragline silk, but its study has identified the ingredients and combinations necessary for manufacture in the artificial world.

Weaving and paving its way into the medical field, the spider’s silky threads may have medicinal application. Arachnophobes need not fret, though – spiders might be of more economic value than one would expect. Forget paracetamol: a pharmacy near you will soon be updating to brands such as ‘webetamol’. As for dressing a graze? You’ll be sure to invest in a durable, reliable roll of cobweb, which will do the trick better than any of the synthetic plasters stocked in chemists at present.

Spider webs rival the strength of steel and the elasticity of rubber, so the production of new bio-based adhesives seems promising as a greener replacement for the current petroleum-based merchandise. Scientists presently lack knowledge about web glue, the coating of web threads, but it is thought to be made of glycoproteins, or proteins with sugar units attached. Irrespective of its makeup, it is boasted to be one of the globe’s strongest biological glues. Even the military has expressed a keen interest in these fibres, hoping to create thinner but stronger packaging films for soldiers’ readymade meals. Textile companies responsible for the manufacture of nylon and Lycra are also monitoring such developments with an eager eye.

Another remaining spidery mystery is how a huge web plastered Lake Tawakoni State Park in Texas, when a pandemonium of spider ‘sheets’ trapped the park in a wide film in August 2007. Texas was in complete awe as the superweb drew over 3,000 visitors over the three-day Labour Day break.

Texas’s wasn’t a typical web – it was “sheet webbing”, entirely blanketing a large area of trees, and typical of a web spun by a funnel spider. Observations suggest that the spider population of the park expanded due to the wet conditions of the summer, resulting in a rather large abundance of small insects for the spiders to feast. To balance the food web, a mountain of spiders appeared to spin a web big enough to feed the entire colony.

If genetic engineering can generate synthetic fibres of spider web, the future may just pose the possibility of genetically engineering Homer Simpson’s Spider Pig. From artificial tendons and ligaments, parachutes and bulletproof vests, we might have to reconsider our view of this eight-legged creature, because without it we may not have a leg to stand on in the future. The spider’s products could be instrumental as we progress into a new decade.

The spider is a powerful creature which may be emerging as king of the jungle. As an Ethiopian proverb states: “When spider webs unite, they can tie up a lion.”

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