Videos of Laura and her oscillatory responses to web motion and Lumi, cleaning, repairing and weaving |
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Vibrational behavior of juvenile Nephila clavipes (banana spider or golden silk spider) |
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Twice I have noticed that when I disturb the web, the web suddenly starts vibrating at perhap 5 - 10 Hz (speculation). The web then instantaneously stops vibrating. It occured to me that perhaps this is a defensive response. When the web is perturbed in a hostile manner (i.e. different from motion induced by wind etc) then the juvenile banana spider ( Naphils clavipes) will start pumping the center of the web, just as a child pumps a swing. The spider seems able to pump the web at its resonate frequency - initiating and terminating high frequency web motion by stopping the pumping. | |
Here are two short video segments demonstrating the vibrational
response to disturbing the web. I must admit, that this response is
not as dramatic as when I did by accident yesterday - but ...
I have prepared 2 slow motion mpegs of the vibrational response. Laura appears to anchor all 8 legs and swing her thorax from side to side (laterally) at a very high rate - perhaps 10 - 20 Hz? In addition, the high speed lateral motion is packaged in approximately 1 second pulses where she appears to shift the locus of the vibration from left to right and back again - thus making it extremely difficult for an approaching threat to accurately locate her. The pulsing is difficult to see in the videos below - but can readily be seen in this one (mpeg compression from the camera)
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Jun 6, 2004: Videos of my sister, Lumi: web repairs and the vibration response |
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Jun 25, 2004: Videos of Lumi: rebuilding her web - the circumferential elements. Note that she is repairing only the bottom half. You will see that she weaves to the left and then to the right, but never continuously in a circle. |
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Reference links |
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I have located some references about defensive behavior. Vibrating the web
is apparently well known.
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C. Frank Starmer