Spinybacked Orbweaver (Gasteracantha cancriformis) mature female
College Station, Texas 2006

Photography by Lorraine E.

This species has a hard abdomen armed with six spines, two pointed rearward, and two pointed to each side. Coloration varies considerably among races; in Florida the common race has a white abdomen with red spines, while in other locales the abdomen may be yellow, and the spines black.  In this specimen, photographed by Lorraine E. in College Station, Texas, the abdomen is red, and the spines are black.

Colloquially, this spider is often known as the "crab spider", not (as with the Thomisidae) because of the way it moves, but because the hard abdomen has the appearance of a crab's shell.

The orb web is similar to that produced by other orb weavers, but lacks the central stabilimentum produced by Argiopes, and often has a multitude of irregularly spaced tufts of silk scattered over the web. I count at least 22 radial strands in this web.

Note the detail provided in the high-resolution photo below.  This attests to the Lorraine's expertise as a photographer, and an unusually steady hand. 

The bite of Gasteracantha cancriformis is not known to be harmful to man. The male (not shown) of this species may be found in every month except December and January where they are not subjected to freezing weather. Females are found as adults throughout the year.

Egg sacs are deposited on the undersides of leaves near the female's web. The eggs hatch in 11 to 13 days.