“Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.” - Dr. Marie Curie

The Halloween season is famous for all things scary – skeletons, horror movies, ghost stories, haunted houses, and of course, creatures we love to hate, spiders not least among them. But in the eyes of science, spiders just might qualify to sit at the superhero table instead of the villain table. Spiders have many incredible abilities. Most famously, they produce silk. Unlike silkworms, however, spiders can produce more than one type of silk, with different properties, and use them for a myriad of different things. Because of this, spider silk has immense engineering potential for human application.

The aforementioned properties include durability, water and humidity resistance, high tensile strength, elasticity, extensibility, temperature resistance, and biodegradability. In fact, when comparing spider silk to steel and Kevlar on a weight-to-weight basis, spider silk wins out. It’s even tougher than the industrial fiber, aramid, which is used in military and aerospace applications (e.g., marine cordage). Spider silk is more waterproof than silkworm silk, and can absorb three times the impact force without breaking. Spider silk itself is such a complex protein fiber that we still struggle to make our own version with any efficiency.

These features make it ideal for a range of uses, such as replacing Kevlar in bullet-proof clothing. Other possible applications include seat belts, parachutes, ropes, nets, and other cords. It could be used to protect boats and other vehicles from rust and to make fiber optic cables and biodegradable bottles. In medicine, spider silk could be used to improve surgical thread, bandages, supportive structures for weak blood vessels, and for creating artificial tendons or ligaments. It could also be used in the textile industry to create lightweight, water-resistant clothing, and by musicians in violin strings.

Super indeed, but why on Earth would a little spider need such a strong, versatile material? Because spiders use their silk in versatile ways! Spiders have been documented using their silk as nets, lassos, whips, binds, disguises, fishing lines, safety lines, lures, bedding, housing/shelter, flying (ballooning), communicating, diving bells, door hinges, water collection, a source of protein, nursery, wrapping paper, snares, alarm systems, lunch boxes/plastic wraps, wrapping paper, and even for trails to find their way back home. Applications vary, of course, by the species of spider and its needs.

For example, baby spiders (spiderlings) disperse themselves by ballooning (a.k.a. kiting). They do so by raising their abdomens to the sky, releasing some silk, and taking advantage of electrostatic repulsion to generate lift. Spider silk and Earth’s surface both have a negative charge, and because like charges repel, the spiderlings take flight! They can sense electric fields with the hairs on their legs and use that information to make ballooning decisions.

The diving bell spider (Argyroneta aquatica) relies just as heavily on keeping its book lungs dry as any other spider. However, it hunts underwater. This spider uses its silk to create a diving bell (hence the name), affixed to aquatic vegetation, which it uses to trap air underwater. When it goes out to hunt, it makes sure to take a proverbial scuba tank with it (sticks a bubble to the hairs on its abdomen).

Trapdoor spiders use silk as door hinges to their burrows. Jumping spiders use silk as a safety line when they jump (like a bungee cord). Nursery web spiders use their webs to make nurseries for their spiderlings. Male nursery web spiders use webs as wrapping paper/plastic wrap to offer nuptial gifts to the female. Male spiny orb weaver spiders let females know they’re suitors rather than food by plucking her web in a very specific pattern. (Fun fact: A spiny orb weaver egg sac is laced with dark green silk!) Examples of web uses are almost as varied and numerous as spider species themselves are!

There are seven types of silk a spider might produce and use. The first is ampullate major silk. This is the type of silk orb weavers, for example, use as their dragline – used for the outer rim and spokes of a typical web. It can also be used as a safety line or for ballooning. The second type is ampullate minor silk, which is used for temporary scaffolding while weaving. Flagelliform silk makes up the capture lines of a web. Aciniform silk is used to secure or wrap prey (may also be used in seemingly decorative web structures called stabilimenta). Male spiders may also use aciniform silk to make sperm webs. Female spiders, on the other hand, use the fifth type – tubuliform silk – to wrap their egg sacs. Aggregate silk is used to create sticky globules (the proverbial glue that prey gets stuck to). Lastly, piriform silk is also an adhesive – this type is used to make attachment points in a web, bonding threads that would otherwise be separate.

So, even if these creepy-crawlies give you the heebie-jeebies, perhaps knowing more about their unique superpower can help you garner some appreciation for their contributions to the web of life, including our own lives.

Have a happy and safe Halloween!

Written by R. L. Nevinczenko. | © 2024, Quality Science Labs, LLC.
Photograph credit: Sudhakar S. via Pexels (Pexels license).