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Agelenidae Funnel-web Weaver Sam Houston National Forest, TX 03 Jul 2009 Thanks to Marney M. for these excellent photographs, taken with a Nikon D50.
Marney (a gentleman) wrote: "I was out, with my family, at Double Lakes Recreation Area in the Sam Houston National Forest on July 3rd, and shot these pictures of a spider in its 'lair'. I found your website during an Internet search and was wondering if you can identify this critter." I thanked him for the excellent photos, and asked if he could resend them, not as email photo attachments (which the mail server will automatically reduce to a low resolution for email transmission) but as image file attachments (that the mail server will send without modifying). He did that immediately, and enlargements of selected portions of both photographs are posted here, showing important anatomical features not visible on the email attachments initially received. I was struck, on first viewing these, by the similarity these photos bear to a set of images I remember seeing, as a young child, in a nature encyclopedia. The encyclopedia, which I recall to have been published in the 1920's, provided a well-written article on funnel-web weavers, and told of the biology of such spiders, how they build their funnel-web snares, and the mechanics of how they kill and consume their prey. Such accounts, supplied with beautiful drawings and well-illustrated photographs, caused my interest in nature to blossom and grow. Now I wonder if these pages will grip other young minds, with similar effect.
Willis J. Gertsch, at the time Curator Emeritus, Department of Insects and Spiders, American Museum of Natural History, published in 1979 an excellent book on arachnids, titled "American Spiders". In this book, Gertsch devoted a total of five pages to the funnel-web weavers. He mentions, in these pages, that the Agelenidae (which, then as now, was devoted to the funnel-web weavers) comprise a numerous and diverse family of over 400 species found in the United States. Presently, due to a number of important revisions to arachnid taxonomy, the Agelenidae of North America are represented in but 9 genera and 85 species. For example, the Amaurobiidae (10 N.A. genera, 97 species), though once included within the Agelenidae, are now recognized as mostly builders of cribellate retreats with radiating tangles, and--for an ecribellate subset--sheet webs with one or a plurality of retreats, or small sheet webs that they hang from, inverted. The specimen depicted in Marney's photographs may be a species in the genus Agelenopsis, but methinks it would be foolish to attempt to assign a specific genus or species from these photos. The cinching anatomical features needed for such assignments are simply not visible. On the other hand, due to the apparent arrangement of the eyes, it seems unlikely to be in the genus Tegenaria, whose eight eyes are of roughly equal size, though their anterior lateral eyes (ALE) are slightly larger. The remaining eight Agelenidae genera also have eight eyes, but their ALE are both dramatically larger and relatively close together, with the much smaller anterior median eyes (AME) immediately above them. In the first photograph posted here, the reflection of Marney's flash appears to be directed from two large ALE, with another reflection that could be produced by two smaller PLE above and between them. At least that's the way it seems to me. The funnel web, in general, is said to be similarly constructed by all species in the Agelenidae. Gertsch described it as having both an entrance and an exit, the latter hidden from view but supplying a propitious way out of a nasty situation should the need arise. Spread before the entrance is an expansive sheet web that beguiles naive insects who mistake it for a nice place to land and rest. The spider, whose tarsi are unencumbered by any structures beyond their three claws, races over the sheet web with facility, capturing the foolish interlopers and producing therefrom a nifty repast. The sheet web gracing the threshold of the funnel retreat is, according to Gertsch, a work of a lifetime for the funnel-web weaver. She constantly adds to it throughout her existence. ---------- Did this sparse tidbit of information pique your interest in arachnology? I hope so. You may have gotten the impression that much is yet unknown about North American spiders, and if so, that was not a mistake. Ignorance about our arachnid friends--they are, in the main, rather beneficial, not the enemies most of us imagine them to be--is measured by the ton. Rather than discouraging you, that fact should make you want more than ever to get involved in helping us fill in the gaps and make strides forward in our understanding and knowledge. The field is still wide open, quite contrary to what you may have previously believed. So, consider doing as Kendra did and get directly involved in pushing our knowledge forward. If you happen across a spider in North America, please photograph your discovery and send me copies of your photos. Whenever possible, every inquiry is answered immediately--I try to answer every email inquiry within minutes of reading it, and every telephone inquiry is answered on the spot, as most (alas, some emails do fall through the cracks from time to time) who call will testify. * TERMITE ENCOUNTERS * SNAKE ENCOUNTERS * SNAKE BITE FIRST AID * SNAKE EXCLUSION * SPIDER ENCOUNTERS FOR 2008 * SPIDER ENCOUNTERS FOR 2007 * SPIDER BITE FIRST AID * SPIDER EXTERMINATION * PUSS CATERPILLAR ENCOUNTERS * PUSS CATERPILLAR FIRST AID * PUSS CATERPILLAR EXTERMINATION * Assembled & Edited by Jerry Cates. Questions? Corrections? Comments? BUG ME RIGHT NOW! ---- Ph: 512-331-1111 ---- E-Mail ---- Privacy ----BugsInTheNews * --0a0s-- |
