— This article by Jerry Cates and Sheri, first published on 20 February 2010, was last revised on 23 April 2016. © Bugsinthenews Vol. 11:02(09).
The following terse and pithy email was received on 19 February 2010:
“It looks flat here. When I urged it into a jar it bent it’s legs like most spiders look. It is very skinny. The slender little body is yellow and looks like a flowers pollen. I had to take pic with my iPhone. I will try to find my other camera. Just wondering if we should kill it or not. Thanks”
Attached was a single photo of what appeared to be a spider, on the inside surface of something outdoors. I enlarged the photo and cropped it, as shown below. Then the photo was converted to a black and white image and printed out, so it could be made into a line drawing, as shown to the right of the photo.
The interesting thing about this spider is its long legs, particularly legs I, II, and IV (leg III is of normal length). Before continuing, perhaps it should be explained why Sheri’s photo is even being posted here. What can be determined from so blurry a photo? Is it even worth the effort? Answer: much, and yes. This spider is no ordinary arachnid, and that much can be said from just a glance at Sheri’s blurry, out of focus photograph. As with all the photographs I receive, every effort is made to learn as much as possible, even with media that are not ideal. Minimal cue analysis is surprisingly useful, once you get the hang of it. Sometimes, of course, it fails by leading me into a false identification, but even then much is learned. And that is what life is about: making mistakes, and learning from them. Never fear making a mistake. Worry, instead, that you might miss a learning opportunity by being too cautious.
Notice, for one thing, that six of its eight legs are very long and skinny. Two of these legs, at one end of the spider’s body (in the bottom of the photograph) are extremely long, and stretch out longitudinally, directly in line with the body. These legs are flanked by two other legs that are about the same length as, and are positioned almost identically to, the two legs at the very opposite end of the spider’s body (in the upper portion of the photograph). The remaining two legs, which appear much shorter than the other six, are positioned so that they stretch latitudinally, rather than along the long axis of the spider’s body. It so happens that this leg arrangement, assumed when the spider is disturbed, is generally diagnostic of certain members of one family of spiders in particular, the Tetragnathidae, or the longjawed orbweavers (sometimes known, colloquially, as “stretch spiders,” because their faculty for positioning their legs in this manner allows them tostretch their bodies along tree limbs and twigs, as a means of hiding from predators). It is also a leg arrangement that–at least to the best of my knowledge–is never observed with spiders in any of the other families.
There are, of course, other spiders with extraordinarily long legs. For example, the cellar spiders, also known as daddylonglegs, in the Pholcidae family, come to mind. These latter spiders even arrange their legs at rest so that four are stretched out to the front, and four are stretched out to to the back. But all eight of their legs are about the same length, and one never sees the stark linearity in the way the legs are stretched out that is seen in the Tetragnathidae, mostly because the Pholcidae reside in dome sheet webs or other kinds of webs that are placed in dark, obscure corners, in caves, and in similar locations where hiding from predators is secondary to trapping and consuming prey.