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.
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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 (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)
Has anyone seen this and
is it a defensive response?
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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.
Copyright 2004 C. Frank Starmer
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