Spiny-backed Orb Weaver Gasteracantha cancriformis

The Spiny-backed Orb Weaver spider is native to the Americas (North, Central and South) and has 6 spikes on the edge of its back. These photos were taken by Alexandra Makhnina in Mexico.

The round web or orb that she weaves. The female, as usual with spiders, is much larger than the male, which doesn't have the prominent spikes.