Tuesday, May 17, 2016

Spiny Orbweaver

Spiny Orbweaver, Gasteracantha cancriformis
Orbweavers, as mentioned before, are found throughout the world and vary in size and appearance, but they are all associated with the classic orb web and, more often than not, it is the female that is larger and more colorful than the male. One such distinct species found throughout most of North America, including some of the islands, is the Spiny Orbweaver, also known as the crab spider, jewel box spider, and smiley face spider. While the colors may include white, orange, yellow, black, or red, the females, about 5-9 mm (0.2-0.35 in) in length and 10-13 mm (0.4-0.5 in) width, all have six pointed abdominal projections referred to as spines. The males, while also with some color variation, are only about 2-3 mm (0.8-0.12 in) in length and lack spines, but may have posterior small humps.

Female spiny orbweaver in the shade of a grapefruit tree.
The spiny orbweaver can be found in woodland edges, nurseries, and gardens, but are also commonly found in citrus groves. The lifespan for this species is short with males dying approximately six days after successful sperm induction to females, and the females die soon after depositing her egg sac of 100 to 260 eggs. When they hatch, the spiderlings will remain in the carefully constructed egg case for 2 to 5 weeks of age. When they leave, they are considered mature. New webs are constructed each night for structural security, always with tufted silk that some studies suggest could be warning flags for birds so they do not fly into the web and destroy it. As with other orbweavers, the spiny orbweaver waits for pray to land in her web in which she will paralyze it and eat it, if smaller than her, but if it is larger, she will wrap it in silk before carrying it to the center to consume. Although their colorful appearance and spines may have an anti-predator function, spiny orbweavers are harmless to humans and are often considered a beneficial species.