SPIDER SILK

SPIDER SILK IS 5 TIMES MORE STRONGER THAN STEEL

A bacteria that produces biosynthetic spider silk was engineered by the researchers at Washington University in St. Louis. This new kind of silk is not made by killing tonnes of silkworms but actually produced by bacteria. Not only that, it is just like natural silk but stronger than steel!

At best, spider silk might compare to steel when it comes to tensile strength, which is the largest stress that a material can withstand before breaking. For one variety of spider silk the value of tensile strength is just above 1 GPa, a unit of measuring force per unit area. That equates to a mid-range value for steel, where strengths range from 0.2 GPa to nearly 2 GPa.

The amazing thing is that the material is biocompatible, which means it could be used inside the human body for things like stitches too. They don't need to be removed either as the are eventually absorbed by the body

Each spider and each type of silk has a set of mechanical properties optimised for their biological function.

 Uses

Spiders use silk for a variety of functions:

Swathing silk for the wrapping and immobilisation of prey. 

Webs for catching prey using sticky silk - it is elastic to prevent the prey from rebounding off the web.Orb web

Draglines which are used to connect the spider to the web, as safety lines in case a spider should fall and as the non-sticky spokes of the web. Dragline silk is the strongest kind of silk because it must support the weight of the spider.

Parachuting or ballooning which is used to aid the dispersal of young and to find new areas as a food source. Silk is released and is caught by the wind to lift the spider up into the air - flying spiders!

Shelters such as burrows or nests

Egg-sacsWolf spider and eggs

Mating: male spiders weave sperm webs on which they deposit sperm and subsequently transfer it to their front palps, ready for placing on a females genital organs. Some species make a web and coat it with sex pheromones to attract a mate


Some interesting web facts:

1. Not all spiders weave webs.
2. Spiders do not stick to their own web because only the central spiral part of the web is sticky, not the spokes.  The spider knows where to tread!
3. Webs lose their stickiness after about a day due to factors such as dust accumulation and exposure to air.  In order to save energy the spider eats its own web before making a new one so the protein used for the silk threads is recycled.