Spiders developed all sorts of uses for the silk that they produce. They make houses through it, protect their eggs with silk-sac, and make traps to catch prey and so much more. Many spiders use their silk for personal protection too. They shoot their silk to an aggressive insect or to another spider whenever they are threatened or offended. The black widow is a classic example of a spider that truly makes use of its silk to kill other spiders; after mating, the black widow is inclined to kill its mate by wrapping it with its silk until it suffocates to death. The black widow either feeds on their mate or stores the wrapped mate for future needs.
In an industrialist's point of view, silk is a very ideal construction material that can be used in the medical industry to warfare and so much more. With 50% of the spider's silk being pure polymerized protein (scientifically known as fibroine), the spider's silk took on an amazing molecular weight of 200 to 300 mols, which is actually heavier than so many other elements in the periodic table. Furthermore, microscopic images of the spider's silk revealed that the fibroine making up the silk is actually in a very systematic orientation, contributing to the extra strong characteristic of the material.
How Do Spiders Spew Solid Silk?
First, spiders have this unique characteristic to spew liquid silk that only becomes solid when exposed to air. The liquid leaves the spider's body through their glands and then hardens or polymerizes after in is exposed to air. Being made from protein and other organic materials, the polymerization of the liquid becomes too difficult for us to replicate. There are seven types of glands in a spider's body that are responsible for the production of silk, however, no spider specie has been found to have all these six glands. However, all spider species have the Glandula Aggregata which is the main gland for producing the sticky material that polymerizes to become the actual silk. All the other five glands may or may not be present in a specific spider. So, the glands are:
1. Glandula Aggregata - The gland for producing the sticky material that is the main component of the spider silk.
2. Ampulleceae (major and minor glands) - This is the gland most commonly found in hunting spiders. They use this gland to produce the walking threads which help them get from one place to another.
3. Pyriformers - Of course, the silk will not attach itself to walls, ceilings or other materials if the spider will not make it to. The only way by which spiders are able to do so is by utilizing this gland.
4. Tubiliformes - Have you ever seen a spider egg-sac? The egg-sac takes a very unique shape if compared to the regular structures made by the spiders. In order to make such a protection chamber for the eggs, the spider has to make us of its Tubiliformes.
5. Aciniformes - This glands works very similarly with Tubiliformes, the only difference in their purpose is that this is gland is used to encapsulate the prey and not the eggs of the spider.
6. Coronatae - If ever you have seen a spider's nest, you will see that their nests have an axis for sticking the threads around it. This axis is made by the gland called Coronatae.
Another very interesting thing about spiders is that they can just recycle their silk as easily as eating it. The silk can give them nourishment too (being made of protein). Thus, whenever their spider traps or house loses its adhesiveness maybe because of the rain or of any other damages, they can simply eat it and then construct a new one without wasting anything or whatsoever. The spider has a special organ for digesting the web since the web is actually a very strong material that cannot be easily digested under normal circumstances.
According to spider silk experts, we are far from mimicking the complete characteristics of the spider web but on a yearly basis, we are also making good progress in this endeavour. At present, we are able to produce a silk that is closely related to the spider web. It is made from yeast and other bacteria that are laboratory-synthesized to have characteristics similar to the spider's web (although not quite). Developers of the material are hoping that it can be used for many different construction purposes in the near future.
Although our scientist today do not really understand yet how the actual silk is made by the spiders, the findings alone that the silk is made of at least 50% protein is already helping them so much in their quest to make good uses of the spider web, artificial or not. This understanding will eventually lead these scientists into finally developing a material that may replace plastic and Styrofoam, a really big breakthrough in materials engineering really.
Scientists are optimistic of that day when they will be able to crack the genetic code that makes up the spider's silk. Only by then will they be able to completely replicate the silk and start using it for things that can bring about great changes into humanity.