[Editor’s Note: Our normal Sunday Virtual Safari will be released tomorrow]
We’ve been witnessing the changing of season in which the vibrant green of summer is slowly but surely giving way to the drier tawny winter.
This seasonal change is no more evident than early in the morning where the longer autumn nights lift and provide us with beautifully still misty conditions.
On these days, spider webs provide the perfect platform for tiny moisture droplets to gather as dew, thereby making the webs far more noticeable than usual. Seeing these webs reminded me of the incredible substance that they are created from…silk.
Legend has it that silk was originally discovered as a weavable fibre in the 27th century BC by a Chinese Empress while sitting beneath a mulberry tree, sipping on a cup of tea, and a silk cocoon fell onto her lap. However, this was not spider silk but rather that of the silkworm (Bombyx mori). Towards the latter half of the first millennium BC the silk trade boomed and gave rise to the famous Silk Road which, for long periods of time, held silk as a more sought-after commodity than gold as merchants from the East were trading luxurious silken garments for materials such as gold, silver and wools from the West. It was regarded as a luxury fabric for its durability and incredibly soft texture.
Spider silk is however produced in far less quantities than that of the silkworm and so was not used as a resource for the Silk Road. Spiders have special silk glands where the substance is initially in liquid form and only once it hardens is the spider able to use this in conjunction with small structures on the end of their abdomen called spinnerets to start spinning their web.
There are up to seven different types of silk that spiders spin for a variety of different uses. These include, but are not limited to, dragline silk that is used to anchor the web, stickier capture silk which captures their unsuspecting victims that fly into the web and even a type that is used to cocoon their egg sacs.
Interestingly enough though, not only do spiders make use of the superb adhesive qualities of the spider silk but some birds, like the Long-billed crombec, will seek out spider webs and carry bits of it back to their nests to secure their gathered nesting material together. There are even many documented cases of Gabar goshawk living with community web spiders in their nests. The belief is that these birds specifically carry parts of the web with the spiders in it in order for them to keep the pests of the juvenile birds at bay.
However, recent studies into the properties of spider silk have given scientists the confidence that it may not only be used by birds but also by humans. The dragline silk, being used for the framework and radii of the web, is called this because as the spiders walk, they always leave a trail of this silk behind them. It’s the combination of the strength and stretch of this silk that has scientists excited about the possibilities of using it medically for artificial ligaments and repairing severed nerves as well as the military for a lighter, but stronger, bullet proof vest and even for lightweight parachutes.
Sounds almost too good to be true, right? So, what’s the catch? Especially as spiders don’t produce huge amounts of silk and even if they did it is not very easy to harvest it. Now this is where it gets interesting; after using different methods to try and produce synthetic spider silk it’s been found that the most efficient way of producing it is by using silkworms. Through the process of gene editing, the silkworms are able to produce a combination of silkworm and spider silk with enough tensile strength and ductility to stretch long enough without becoming brittle. This would allow us to harvest the necessary amount to make all of these medical advancements feasible.
Spiders play a hugely important role in the ecosystem as they keep the insect populations in check, as well as providing a food source for many other insects, but who knows, they may even play a crucial role in medical advancements of humankind in years to come?
I may not be an advocate of genetic manipulation but what I find most fascinating about this whole subject is that given all the advances of modern technology there are still wonders of nature that we have yet to be able to replicate.