Stretch

Tetragnatha montana (underside)

While I was photographing pollinators around our Skimmia bush the other day, I spotted the spider in the picture above; though it was small and very slim, its bright silvery-white striping was eye-catching. I took the picture and went in to identify it — only to discover that this was the underside, and that there are several species that show similar patterns. Getting the "top side" photo took a few additional days (since I didn't want to disturb her), but this afternoon, I finally found her stretched out on a leaf, catching some sun (see below). It turns out that the plain dark "sternum" of the spider's underside is important; some species show a little yellow triangle at the head end. Tetragnatha montana, however, does not. The combination of the lack of the yellow triangle on the "sternum", a yellowish-brown carapace (the top side of the spider's front section) with a dark midline (and a few radiating dark branches) and that dark underside to the abdomen with its two silvery-white stripes is distinctive. This is a common and widespread species in southern England.

The six British species of Tetragnatha spiders, informally known as "stretch spiders", are notable for their very long legs and very long abdomens. They'll leave their webs if disturbed, and extend their legs straight out in front of them along a blade of grass or reed stem or twig (i.e. "stretching"), which helps to camouflage them. They've got 8 eyes in two rows of four; click on the photo below to enlarge it if you want to see them clearly. The spider's location (away from water) and its size (its body just under half an inch long) also suggest this species. To be 100% sure, I'd have to examine its genitalia under a microscope — and I can't even pretend to be interested in doing that at this point!

Tetragnatha montana