Spider webs

  • #1
Ivan Seeking
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Main Question or Discussion Point

Lately I have seen a number of spider webs [really, it looks like a single strand] running horizontally from one tree to the next. This morning I saw one over fifteen feet long, nearly perfectly level, and suspended abouty eight feet above the ground. How does a spider span the fifteen feet from limb to limb?

One day I was walking down and saw what appeared to be a twig floating in mid air, right at eye level! Only when I got close could I see the web. This was a twig about six inches long, and had at least a 3/16" diameter - relative to bugs and moths it was quite heavy - so the silk is surprisingly strong. It is also very thick as compared to most silk seen in other webs.
 
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  • #2
DaveC426913
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Spiders can either:
1] stand on one branch, let out several feet of strand in the wind until it blows over and contacts the other tree
2] dangle themselves from one branch and hang, blowing in the wind until they reach the other tree
3] climb down one tree and up the other

Either way, once they have bridged the gap, they then climb back up the tree to the branch across from their starting point, reeling in the slack strand as they go.
 
  • #3
honestrosewater
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Ha, I was going to suggest that they just swing from the first branch, but I thought it was unlikely. How much energy would a spider need to move from rest at the bottom up to the second branch, on a fifteen foot string?

Maybe you should set up a camera. :biggrin:
 
  • #4
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A spider does not weigh very much so the wind often provides more than enough energy to move a spider over large distances, and using some lines the spider may move in "mysterious" ways.

Also, spiders may just release a lengthy line of silk and let it float until it attaches to something. Currents of air will carry the silk line. Baby spiders use such silk lines to float up into the air and reach destinations at large heights, like the windows of apartments that are many stories above the ground.
 
  • #5
DocToxyn
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gerben said:
Baby spiders use such silk lines to float up into the air and reach destinations at large heights, like the windows of apartments that are many stories above the ground.
This behavior is called "parachuting" or "ballooning" and is used to travel long distances and might also be used during web construction. Darwin observed such behavior on one of his voyages:

One day (November 1st, 1832) I paid particular attention to this subject. the weather had been fine and clear, and in the morning the air was full of patches of the flocculent web . . . The ship was sixty miles distant from land in the direction of a light but steady breeze. Vast numbers of a small spider, about one tenth of an inch in length, and of a dusky red colour, were attached to the webs. There must have been, I should suppose, some thousands on the ship.
-- Charles Darwin, "The Voyage of the Beagle", chapter VIII.
As far as strength, I have seen it stated that spider silk is five times stronger than steel of the same diameter and considerably more elastic.
 
  • #6
Ivan Seeking said:
so the silk is surprisingly strong
it is considered one of the strongest materials.

interestingly, scientists have been able to splice in the sequence of this protein in place of lactalbumin (using Cre-Lox methods i think - in essence "knock-in goats") to produce it from their milk, for applications such as bullet proof vests.
 
  • #7
brewnog
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What an odd coincidence, I was about to post the exact same question this evening after discovering an improbable web spanning the interior of my car!

Assuming that there's no wind inside my car to allow Charlotte to carry out 1 or 2, as detailed by Dave, how does she prevent her silk from sticking to the floor when she's crawling along the floor from one side to the other?
 
  • #8
Moonbear
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Well, quite possibly, Charlotte climbed across the ceiling and gravity kept her web from sticking to nearby surfaces? You might have to ask Wilbur though. :rofl:
 
  • #9
DaveC426913
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Spiders are capable of spinning many types of silk, each for a different purpose. The ones they lay to start a web are not sticky.

BTW, neither are their safety lines, nor the radial strands in their webs - the ones they walk on; only the the concentric strands are sticky.

They're incredibly well-adapted critters.
 
  • #10
brewnog
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Moonbear said:
Well, quite possibly, Charlotte climbed across the ceiling and gravity kept her web from sticking to nearby surfaces? You might have to ask Wilbur though. :rofl:

Hmm, why didn't I think of that?
I'm annoyed now that Moonbear thought of something I didn't!

Meanwhile, Dave, please carry on! I might hang around here a bit longer if biology can be this interesting! Insert here enough smilies to keep Moonbear happy
 
  • #11
DaveC426913
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This is just stuff from grade school/high school. Biology's not my forte.
 

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