While mowing my yard this morning, I almost ran into this enormous spider web. This spinybacked orbweaver had woven a web more than 6 ft. in diameter, stretching across the branches of an oak tree.
The University of Florida Dept. of Entomology and Nematology explains:
One of the more colorful spiders in Florida is the spinybacked orbweaver, (Gasteracantha cancriformis), is not as large as some of the other common orb weavers, the combination of color, shape, and web characteristics make G. cancriformis one of the most conspicuous of spiders. The colloquial name for this spider in parts of Florida is “crab spider,” although it is not related to any of the families of spiders commonly called crab spiders, e.g., Thomisidoe.
This species can be easily distinguished from all other spiders in Florida. Females may be 5 to nearly 9 mm in length, but 10 to 13 mm wide. They have six pointed abdominal projections frequently referred to as “spines.” The carapace, legs, and venter are black, with some white spots on the underside of the abdomen. The dorsum of the abdomen is, typically for Florida specimens, white with black spots and red spines. Specimens from other areas may have the abdominal dorsum yellow instead of white, may have black spines instead of red, or may be almost entirely black dorsally and ventrally. Males are much smaller than females, 2 to 3 mm long, and slightly longer than wide. Color is similar to the female, except the abdomen is gray with white spots.
The bite of this common species is not known to cause serious effects to humans.
Source: http://entomology.ifas.ufl.edu/creatures/beneficial/g_cancriformis.htm