Excerpts from Jim Conrad's
from the February 23, 2014 Newsletter issued from the Frio Canyon Nature Education Center in the valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau, USA
We're having a series of warm days now and butterflies, spiders and other invertebrates are warily making their appearances, though we'll certainly have some frosts later on. One spider catching my attention was a slender-bodied one suspended in its web strung among diffuse branches of a grass's spent panicle, shown below:
It measured only about 2cm from front leg tip to back leg tip (¾inch) and what's curious is how it pulls in its side legs, unlike many species who spread all their legs widely when they perch in their webs. When disturbed, this spider drew in its side legs even more, presumably making it less visible to predators, as shown at the top of this page.
Something to notice in that picture is that inside the space framed by the bases of the front legs some unusual structures can be seen. If the spider really gets upset, it abandons its narrow-profile strategy, stretches out all its legs, and starts trying to escape. You can see this happening below:
Volunteer Bea in Ontario figures that we have a member of the genus TETRAGNATHA, members of which often are named Longjawed Orbweavers, or Stretch Spiders. The curious structures at the front of the head appear to be two different kinds of mouthparts. The darker, thicker parts nearest the face are "jaws," more technically known as chelicerae, and which bear fangs, while the slenderer and more extended parts are the pedipalps, which serve as "feelers."
About a dozen Tetragnatha species are listed for Texas and I'm not sure which one this is. It's smaller than most.