After a few months of serious work during which I completed my PhD dissertation defense, I finally have time to blog about spiders again. My friend Andrew Durso recently went to Florida to help collect lizards in a very interesting field study to investigate the evolution of populations on different islands. While Andrew is an accomplished herpetologist, he is interested in natural history in general, and was able to take some spider pictures on a small island in the Matanzas River estuary. This estuary supports a diversity of native habitats and wildlife of national importance.
The spiny-backed orbweaver (Gasteracantha cancriformis) is a pretty spider typically found in woodland edges in the southern United States down into South America. This web-building species, which has six conspicuous abdominal spines, shows interesting geographical variations in color and shape. For instance, the individual photographed by Andrew had a white abdomen and red spines, but individuals that I have seen in Colombia had a yellow abdomen with black spines. It has been suggested that conspicuous colors in spiders may increase their foraging success via the attraction of prey to these colors, but a recent study suggests that this is not the case in Gasteracantha.
Andrew also noticed a few Phidippus jumping spiders, which have typical metallic blue-green chelicerae. These individuals appear to be P. regius (the regal jumping spider), which is the largest species of jumping spider in the eastern United States, and relatively common in Florida. Males are black with white markings on the abdomen whereas females can be grey or orange. The male P. regius can be distinguished from the somewhat similar-looking male P. audax by the shape of the posterior abdominal spots, which are oval in P. regius and more linear in P. audax.
P. regius is usually found in open habitats such as fields or open woods. Females lay their eggs in thick silken nests under the bark of trees, but cracks and spaces in houses may also provide suitable shelter.