Signature Spider

Description:

Argiope luzona (Walckenaer, 1842). The pictures shown above are all photos of the same spider. The first two were taken yesterday and the last two were taken this morning. As you can see, yesterday's photos show both a topside and an underside view, as do those taken today. The purpose of this spotting is to try and demonstrate just one small aspect of what I think may be the greatest (and, as yet, unsolved) problem faced by arachnologists who have have been studying and documenting Argiope Spiders. Science has been trying to find an answer to one question in particular for over 100 years. The question is "Why do Argiope spiders create Stabilimenta (web decorations)" It seems like a simple enough question, but it is anything but simple. Many very good ideas have been put forward by academics, but none has gained universal acceptance. Possibly the most popular one is the idea that the decoration attracts prey to the web, but not everyone agrees and the spiders don't seem to be interested in cooperating very much. Whenever any group of academics gets close to proving a hypothesis (scientific idea), the spiders sometimes throw a spanner in the works by changing the style or size of their decoration. I think my photos perhaps demonstrate one tiny example. Please see Notes below.

Habitat:

This spider was spotted in our backyard. Its web, with the amazing web decorations, was moored on a very young Banana Plant (Musa sapientum) locally known as "Saging". Plant identification - http://www.stuartxchange.org/Saging#:~:t....

Notes:

The decoration on this spiders web yesterday is a fairly common example of a "Four Arm Discontinuous Cruciate Stabilimentum". [These spiders remove their decorations from their webs every night. They then repair or replace the web to keep it in good shape to do its job for the next 24 hours. When the web is in good condition again, the spider rebuilds its decoration]. When I went out to take another picture, this morning, I was fully expecting a decoration of similar size and quality, but there were other possibilities e.g. the arms might now be Continuous, they might be a little longer, there could even be an additional arm to make it a "Five Arm" or there could even be no decoaration (that happens sometimes, in certain circumstances), but I could never have been prepared for what you see in those last two photos. The arms of the decoration are now approximately six times the length of the spiders body whereas, in yesterday's photos they were only three times its body length. All four arms were now continuous (and that rather looks like an afterthought, if you look at the joints in the last photo). The weave of the zig-zag arms is very much thicker and the spider must have used much more silk than it did the previous day. I have to ask myself "What is the reason for this?" and, of course, I have no idea. The burning question is "Was the spider going to these extremes because it was hungry and knew that a bigger, flashier stabilimentum was guarabteed to deliver more lunch by attracting more insects?". I also ask myself if the thicker weave of silk on only one arm of yesterday's decoration was significant. Did the spider think as she approached the end of that decoration "Oh, I'm feeling a bit peckish! Maybe I should have made this a little more conspicuous". To be more serious, this is a truly complicated problem and I fully expect that it will take many more years for science to give us the definitive answer.