Photo Adventures with Curiosity and Learning

Videos of Laura and her oscillatory responses to web motion and Lumi, cleaning, repairing and weaving

Vibrational behavior of juvenile Nephila clavipes (banana spider or golden silk spider)

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 ...
  • Vibrational response to web motion (few sec)
  • Vibrational response (10 sec) 1Mb mpeg Initially I plucked one of the web supports. Then there was a brief delay and she initiated an rapid high frequency oscillatory lateral movement of her body. In addition, the locus of the lateral pulsation, shifts at a frequency of about 1/sec as she shifts her body to the left and then back to the right and then back again. Since is it difficult to actually see her, I suspect that she uses rapid movement to blur the image of a large threat (like me) - thus making it extremely difficult to know what to attack.

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)

Jun 6, 2004: Videos of my sister, Lumi: web repairs and the vibration response

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.

Reference links

I have located some references about defensive behavior. Vibrating the web is apparently well known.
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C. Frank Starmer