The Silk That Spiders Make - IELTS Listening Answers & Explanations

Lecturer: If you dread being taken by surprise by a spider when you're relaxing in front of the TV, you'll no doubt be one of the millions of people who find spiders terrifying. But hopefully, this morning I can change your perception of these creatures. You might continue to find them scary but you might also see them in a slightly different light.

I'd like to focus specifically on the silk that spiders make. The substance they use to make their intricate webs is stored in the form of a liquid protein inside their body and it only turns solid when it's exposed to the air. The common garden spider of the UK can create up to five different types of silk. Some of these silks are responsible for allowing the web to stretch while others make the web less brittle.

It's often claimed that spider silk is stronger than steel but this is misleading. A material can be strong in different ways: for example, it can be stiff, which means it resists bending, and silk is much less stiff than steel. But spider silk does have some incredible characteristics. It can stretch by up to 30 per cent without breaking before returning to its original size. It can even withstand sub-zero temperatures without becoming brittle.

People have used spider silk in many practical applications for centuries. The ancient Greeks used cobwebs to dress wounds and to help stop the flow of blood. Spider silk was used by Indigenous Australians to make fishing lines, and in the Solomon Islands people use spider webs to catch fish. In the 1900s it was used in optical devices, such as in the crosswires in a rifle sight.

If spider silk could be produced on an industrial scale, it could have a wide range of applications. In a recent experiment, scientists used it to help grow human skin in order to treat burn victims. Some companies have even shown an interest in using spider silk to make airbags in cars. They believe it could absorb more of the impact and so limit the impact of the airbag on the body itself. Spider silk has even been considered as an ideal material to use in biodegradable bottles.

However, there's one significant problem. It isn't possible to obtain the amount of silk needed for applications like these from spiders. It would take ages to collect the material from their natural habitat, and farming spiders isn't possible as they are aggressive, territorial creatures who will attack and eat each other. Furthermore, because the silk goes hard when it's exposed to air, it's difficult to work with.

Scientists have tried to overcome some of these problems by taking the spider itself out of the equation. One team of scientists extracted the silk genes from two species of spiders and inserted them into cells from a cow. The cells were grown in the laboratory and produced the silk proteins that the scientists were able to harvest. The proteins were then spun into silky strands and the fibres produced were stronger than Kevlar, a material used to make bulletproof vests, but they were lighter than Kevlar and nearly as elastic as nylon. Scientists have also genetically engineered living goats that carry spider silk genes. The first two goat kids produced in this manner were called Webster and Pete. The hope is that milk from goats like these will contain significant amounts of usable spider silk proteins.

Another approach is to use silkworms. The silk from silkworms can be farmed in ways that spider silk can't and so researchers have looked at making genetic changes to the silkworm. The silk that's produced in this way is a mixture of silkworm silk and spider silk. Initial attempts created silk that was stretchy but not as strong as spider silk. However, researchers subsequently managed to increase the amount of spider silk by a factor of seven. One of the advantages of obtaining spider silk in this way is that the silk is ready for use as soon as it's spun by the insect.

A group of researchers at the University of Nottingham have developed artificial spider silk made of proteins that are similar to those in naturally produced spider silk. This man-made silk can be used in a variety of medical applications. It was shown to act as a scaffold or support for the growth of new tissue. The researchers were also able to coat it with an antibiotic, and their experiments showed that the antibacterial properties of the silk lasted for several days. So, thanks to its ability to release antibiotics in a controlled way, the silk could be used in the manufacture of dressings to treat wounds that take a while to heal.

We may only be a few years away from being able to see some of those applications in use. If the outcome of this research is that we'll be able to create materials with properties similar to those of spider silk, we might also be one step towards eradicating the production of synthetic materials that can have negative effects on the environment.

I hope this has given you an insight into the amazing spider. Next time you see one scuttling across the floor, stop to marvel at what it can achieve rather than jump on the sofa to escape.