Web composition?

[Dom]

Just curious..

What is it made out of and why is it so strong.. I have heard that it is considered to be a stronger material then steal .. Does this fall down to simply strong chemical bonds or van derwall bonds or any of those sort of thing..

On an other point .. I have also heard that the black widows web is one of the strongest webs out there.. why is that .. Anybody willing to tackle these questions?

Thanks
Dom

[Kyle Barker]

i dont know, but watching those widows fish for HUGE*** bugs i believe it!!

[Dani33]

I would like to know the answer as well - good question!

[reverendsterlin]

If I'm not mistaken (and I well could be) I think there are 6 different types of silk used for different purposes.

[Vanan]

Dunno much about the strength aspect but I know that the elasticity comes from the strands not being taut. Kinda difficult to describe but, in reaity, a strand in a web is straight then it's squiggly, then straight then squiggly. The squiggly parts are so tiny and enclosed in a tiny droplet of water that it's difficult to see it with the naked eye. Try looking at a strand under a microscope and you'll know what I'm talking about. I'm trying to describe what I saw in a documentary and am failing at describing it properly.

[Emily-Fisher]

Supposedly, there's this group of dudes that have been studying it for years but still have not come close to figuring out why it's so strong... it's still an unknown fact :)

[ranmasatome]

Its not much but heres what i know about spider "silk"..generalising from what i know about golden silk spiders (orb weavers). All information is taken from researches like Fritz Vollrath. And others like John Gatesy and Cheryl Hayashi and their collegues from the university of california at riverside. its quite a read...i summrized it and added some of my own stuff..lol.

Spider silk has the tensile strength almost as great as steel per unit volume but far greater when in per unit weight.
Bullet proof vest made of kevlar is 3 times harder to break but "silk" is 5 times more elastic. (at least from species like Nephila or golden silk spider)
spider silk comes in all sorts of varieties and varies according to species and uses each species decides to use for it. It is not fixxed that there are only 6 types...i think that there are far more out there...but i can understand that there may be 6 general types that people know of now. if you ever disected a spider and looked at it under a microscope you'll see many different types of silk glands located inside its "abdomen". sometimes a spider mixes its silk. The strongets of all silk a spider produces is called "dragline" silk. it's the silk it produes when it jumps off a ledge etc. and can sometimes be spun at great speeds of up to 1m per second. there are more that 34,000 known species of spiders and each makes its own silk, some that make differnt silk for differnt purposes.
Each silk for this species is about 3-5micrometers thick. And compose of thousands and if not more of filaments that are only a few nanometers thick, too small to be seen by a microscope. Each filament is made of some composite material (e.g in likeness to fiberglass) consisting of stiff sheets of crystalised protein floating in an elastic rubbery matrix. Take one strand of that and times thousands and thousands...and you get very high tensile strength in one strand of web. it is possible that Dragline silk is even stronger with long fluid filled channels interspread among the tightly packed filaments. These help distribute tensile forces from jumping and falling etc. and prevent "cracks" in the web. Besides just structure...Strength in web also come from the proteins that make it. Researches have found that long chains of amino acids (that make a certain silk protein) is dominated certain repetitive sequences..for example...long stretches of only the amino acid alanine. Alanine for example, is good at binding other alanine chains, allowing the protien molecules to line up side by side like logs in a raft. Thus, forming the stiff sheet crystals talked about earlier. silks with polyalanine (many alanine) regions are the strongets tested so far by Gatesy and Hayashi.
Assembly also somes into play, the protiens from dragline silk are secreted by cells on the walls of a long sca-like gland, from which they are funneled as a watery solution into a long, looping duct. this allows the proteins to line up with the direction of flow, like logs in a river, and they become liquid crystal. then in the tapering duct, it is stretched long and thin and bathed in acid. water is than extracted and "recycled". The proteins thus bind and solidify. now doing all this while jumping off a ledge, managing it with your "azz" and doing it all more that 1m per second!! now that's impressive.
All in all, its still not certain in FULL DETAIL how the complex structure of a spider thread emerges from a spiders abdominal machinery. Hope it helped clear some things up..:)

[Dom]

Tx so much .. very interesting read!

[ranmasatome]

np! it was a good revision in physiology for me..:)