Monday, September 08, 2008

the zipper spider

Found this fascinating spider in my garden today...

His web is about 4 feet across

with a zigzag design

right in the center

so, I call him Zipper

It's known as St. Andrews Cross, because of the way it holds it's legs in a cross and hangs upside down in the web. The large white zigzag in the centre of its web is called the stabilimentum or web decoration

In North America, Argiope aurantia is commonly known as the "black and yellow garden spider", or "writing spider," after the mistaken idea web stabilimenta were correspondence.

It has been shown spider webs using stabilimenta catch, on average, 34% fewer insects than those without. However, webs with the easily-visible markings are damaged far less frequently by birds flying through the web.

It is an evolutionary tradeoff the spider can influence every time it builds a new web. The inclusion of stabilimenta is influenced by many factors, including prey density and web location

They're not dangerous to humans, but they do produce about 1400 babies!

This web actually had 2 spiders and I suspect they are planning a family.


Pam said...

I've got a zipper spider who has situated herself in the middle of a window. She builds a new web everyday. She has also produced two brown pouches of babies. The pouches are so intricate, they look like old leather. It's like a NatGeo moment every time I observe her. I enjoyed your article.

John said...

I am so glad I checked out ur site. There are 2 zipper spiders by my house and pool. My daughter said they were poisonous and since we have 5 small dogs I was considering getting rid of them. I think they are beautiful and sure don't want to harm them if not necessary.. Thank you.

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