There is no exquisite beauty…without some strangeness…

~Edgar Allan Poe

I came across this strange spider the other day as I walked through the back gate. I noticed its striking white abdomen moving slowly around its web with a small up and down motion, accompanying a slight twist of the body as it moved. The spider was making its web, an orb web, and the motion I saw was it anchoring the spiral, sticky threads to the “spokes of the wheel” foundation threads (non-sticky) as it circled around and around. I went inside and grabbed my camera, but when I returned, the spider had stopped moving and was obviously feeding on a tiny prey that had blundered into the web in my absence.

The black background created by using my flash made it hard to see details of this unusual spider (click photos to enlarge)

My first photo was less than satisfying – the black and white pattern and odd shape did not translate very well in my flash photo. The black spines adorning the spider’s abdomen tended to vanish into the black background created by the flash.

When I got back with my camera, the spider was feeding on something it had caught in its web

So, I went inside and grabbed a piece of white foam core, clamped it to a tripod and set it up behind the spider so the spider was now outlined in a light background color through my viewfinder. I took a few more shots and went back inside to confirm the identification of this odd-looking species.

Spinybacked Orbweaver

My unusual spider is a Spinybacked Orbweaver, Gasterocantha cancriformis. The scientific name says it all – gaster = belly, acantha = thorn; cancer = crab, forma = shape. Another common name for this species, especially in Florida, is the Crab Spider (although it is not related at all to the familiar Crab Spiders, Family Thomisidae, that are the sit-and-wait hunters we often see on flowers). Although this female is quite small (about 1/2 inch in width), her circular web can be quite large, up to a couple of feet in diameter. They can vary in color (yellowish abdomens and black or red thorns) throughout their range, although the few I have seen here in the Piedmont were all this black and white pattern. The spines are quite stiff and are presumably a defense against certain predators like birds. And the bizarre shape and pattern of this strange beauty is a fitting addition to the season as it almost looks like some sort of scary mask with multiple eyes. Perhaps a costume idea for the future…