Photo Adventures with Curiosity and Learning

July 14, 2007: Nephila pilipes, multiple mates and removing debris

    Video segments: Watching spider behavior has become quite interesting. with my science hat on and my curious eyes open, I wonder about how this happened. How is behavior programmed? Why is behavior programmed? So many questions - we need a National Why Day just to get answers to these and other questions.
  • Two males (23 MB mpg) Two males - interesting behavior here also
  • Male-male conflict And these guys appear to have conflicting goals
  • (18 MB mpg)
  • Female cleaning (26 MB mpg) - A hand washing exercise?
  • Male signaling to the female (my interpretation) (51 MB mpg) This, for me is very interesting. Here, a male and a female, are communicating via a touch response. But the signaling is complementary - he touches her rear leg and she shakes him off. How is the complementary response programmed? No books, no parents - just DNA, organized such that in the female, she exhibits one type of response and in the male he initiates the event. Was the programming of male and female components synchronized or was the programming independent?
  • The female brushoff: Interesting signaling between male and female (52 MB mpg)
  • More male signaling and success - then 2nd thoughts by the female (51 MB mpg)
Another visit to my spider spot near Queensway Secondary School. And full of surprises. The three N. pilipes webs were there and in two of the - the two black color morphs, mating was in progress. For 4 years, in the US I struggled to even find male Nephila but here in Singapore, this is my 6th or 7th instance since January.

The surprise was the the female with invading A. flavescens had two males interested in the mating game. To watch these two males - and her responses was fascinating to say the least. A couple of kids came around a tossed (unfortunately) a small twig into her web. Not to worry - she moved to the twig, while one male was progressing with the mating game and the other supervised the twig removal. All in all, a very productive day.

Unlike Nephila clavipes that lived in our Charleston SC garden (US), where the males tended to orient themselves perpendicular to the female while watching for the right moment, here the males have the same orientation. Also earlier, I observed spider silk on the backs of a few females that seemed associated with the mating game. Today, there was no such spider silk in evidence.

Here is the context of Nephila 1 - A small web 2 meters above the ground with several invading Argyrodes and two males.

jul 14 2757 nephila 1 context

Here is a male approaching the female from above

jul 14 2362 male approach

And retreating for whatever reason

jul 14 2345 male nephila escape

The male on her dorsal side

jul 14 2399 male female nephila

Here the male is moving toward her cephalothorax. I anticipated some weaving where the male lays a sheet of silk around her head. Not much weaving today, if any. You can see the orange blob behind her spinneret - an out of focus Argyrodes

jul 14 2422 male female

A better view of a larger male with an Argyrodes in the upper left

jul 14 2445 2nd male

Here he is inspecting her ventral surface

jul 14 2468 male ventral

And the larger male approaches again. Note the prominent black palp sacs

jul 14 2475 2 males

The smaller male quickly drops with the approach of the larger one (here only the legs of the larger male are evident). How did #1 detect the approach of #2?

jul 14 2476 hasty retreat

The winner of this episode of the competition

jul 14 2483 male winner

with a pair of Argyrodes watching from the side

jul 14 2496 argyrodes

Another episode - male #2 approaches from above

jul 14 2497 male returns

and walks to her cephalothroax

jul 14 2505 male and argyrodes

Both males are now present - one on the ventral side and one on the dorsal side, perhaps thinking about a little weaving action

jul 14 2525 2 males 1 female

To the right, about 30 meters was another Nephila pilipes, #2. The sun was oriented so that some of her legs were illuminated (bright orange) while other legs were in the shadow of the sun. Here also are Argyrodes and a male (unseen). The golden texture of her silk is quite apparent

jul 14 2762 nephila 2 morning sun golden silk

Another view

jul 14 2767 nephila 2 off axis

And later - a male on her ventral surface

jul 14 2870 nephila 2 mating

Back to Nephila #1 - A good view of one male on her dorsal side, two Argyrodes to the right and the other male above.

jul 14 2781 nephila 1 context

The #2 male starts to approach

jul 14 2785 nephila approach

Climbs onto her abdomen near her spinneret

jul 14 2787 2 males 2 argyrodes

And moves about on her dorsal side while the other male seems to be looking for her epigynum on her ventral side

jul 14 2792 2 males 1 female

Just moving about

jul 14 2811 two males playing

The dorsal male leaves and here is returning while #2 is on her ventral surface

jul 14 2838 male approach male mating

A couple of kids came over and tossed a small twig into her web - a bit of frustration from me - but a new opportunity to watch debris removal in the middle of the mating game. Here you can see the female manipulating the twig while the male is seen on her ventral surface. The female manages to pull the twig through her web and the drop it (see below) in a manner similar to what I observed with small flowers dropped into a Leucauge web.

jul 14 2889 male removing twig

Obviously, twig removal requires a supervisor - so here on male is walking about her side while the other male supervises the removal

jul 14 2906 two males twig

Here she grabs another section of the twig with her right front leg

jul 14 2914 grab twig

while the other male watches from a safe distance

jul 14 2921 male watching

She cuts the strand of silkthat holds the twig in place

jul 14 2938 last strand

and drops the twig

jul 14 2939 dropped twig

Feeling safe - the other male approaches from above

jul 14 2945 approach

Gets close to her spinneret

jul 14 2946 approach 2

climbs onto her abdomen

jul 14 2947 approach 3

Immediately the female responded with ther right rear leg and gave this male the brushoff (blurred region of the male and right rear leg)

jul 14 2948 approach female response

He escaped to the side and when she turned around, there was the other male on her ventral surface

jul 14 2949 approach brushoff escape

All in all, a very interesting day. I have about 2.5 hours of video and will add this after some editing

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C. Frank Starmer