Spider Silk Cobweb

The word ‘cobweb’ is usually used for old, abandoned webs like this one that have lost their stickiness, whereas the word spider web is used for those that are still in use.  Another word for a cobweb is gossamer, from ‘goose-summer’, which refers to a time of year when millions of spiderlings float a long thread of extra-fine silk into the breeze until they achieve enough lift to take off and drift further afield.

Not all spider webs are sticky. Several glands in the spider’s abdomen, called spinnerets, produce different types of web for different purposes. There are eight known types of spider silk, but no spider can make all eight. Each spider has a different method of web-spinning and construction. Sticky threads are festooned with rubbery droplets of glue, while some non-sticky threads are constructed like wool with many tiny filaments that trap insects by entangling the little hairs on their bodies, working very much like velcro. 

Spiders use their silk to make webs and cocoons to trap food, hide themselves, and, as in the trap-door spider, to make nests for themselves and their young. Spider silk can even play a role in spider sex, with spiders impregnating the silk with sperm or pheromones. 

When inside the spider’s body the silk takes the form of a pure protein, but when spun it becomes a type of polymer. Spider silk is very strong and very elastic; much is written about how a pencil-thick thread of silk would stop a Boeing 747 in flight. However, that would take the work of billions of spiders, as spider silk is a nano-thread and is usually under a micrometer in thickness. Spider silk is very resistant to drying out or decaying like other proteinous substances, which explains why we have been able to keep it on this chicken wire without it breaking down. If a spider’s web gets worn out and loses its stickiness, the spider will often eat it to recycle the protein.

Humans have used spider webs in a number of inventive ways, to both construct and destruct. It has been used as a surface for painting on, applied to bind and heal wounds, and used as crosshairs on a gun, as fishing lines and as poison arrow tips.