Saturday, August 18, 2012

Funnel Weaver

In the back corner of the barn, I found this wonderful Funnel-web Weaver spider.  It’s a species of the genus Agelenopsis, but I’m not certain which.  My reference book lists several species that might be found in this area.  Identification to the species level involves examination of the spider’s genitalia and that means having the specimen quietly resting beneath some magnifying device.  I usually don’t kill things just to find out what they are.

The spider sits at the mouth of its protective funnel and awaits an indication that some hapless insect has wandered onto the web.  It has chosen a great location.  Flying insects are always entering the barn and then getting trapped by the window glass.  There should be a steady supply of food falling into the web.

The web is constructed as a large flat surface roughly oriented in a horizontal plane.   Movement on this surface alerts the spider to potential prey and it rushes out to make its capture.  The web is not sticky, so insects on the web can freely escape if not quickly captured by the spider.

In order to make escape from the web more difficult, a network of web fibers form a random pattern over the top of the flat surface.  Insects trying to fly or jump to safety are deflected back into the web by the fibers.

The neatest thing about this particular web is the position of the funnel.  The funnel is normally built in a location that offers protection to the spider, so it’s unusual to have an unobstructed view.  This funnel is fully exposed on one side.

The spider spends most of its time in the funnel.  From this position, it can pick up vibrations from the web that indicate the presence of some insect prey.  Captured insects will be brought into the funnel where they are consumed by the spider.

At the rear of the funnel is the garbage dump.  Remains of earlier meals hang suspended in loose webbing.  Excess prey could also be stored here to future consumption.  I pulled out a couple of the bodies and found they were nothing but empty shells.  I didn’t see anything there that looked to be a suitable meal.  I’ll leave the web in place until the spider departs.

5 comments:

  1. Funnel web spikers are an interesting and can be entertaining lot. At least as a kid we enjoyed their response to us putting helpless prey into their traps.

    Thank God they were nothing close to Sidney Funnel Webs or I may no be relating this story to you.


    *smile*



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  2. Great series of shots and notes. btw, which book are you using for spider IDs? I'm looking for a good reference manual.

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  3. Hi Kevin. I used to do the same thing as a child.

    Thanks Ingrid. I use "How to Know the Spiders" Third Edition by B. J. Kaston. The keys seem to refer more to visible features than those requiring magnification. Some of the scientific nomenclature is out of date, but the book covers a wide range of North American species and offers added information about the habits and range of most. I also have "Spiders of the Eastern United States: A Photographic Guide" by Howell and Jenkins. This book has a lot of good photographs, but wouldn't be much good for species in the Western U.S.

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  4. Great shots of the spider and its handiwork.

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