A little late for a Halloween post, my apologies, but I wanted to share what is probably the best-preserved example of a Gibellula-infected spider I have found to date. Gibellula is a genus of endoparasitic Cordyceps fungi that primarily infect spiders. Although the nicely preserved jumping spider (Salticidae) and the fruiting branches of the fungus is what grabs the eye, it wasn’t until I finished processing the photos that a question came to mind for me.
See the white fibers that surround the spider? I see two possible options for the origin of these. First, I should explain a little of what I have read about the life history of these parasitic fungi. Similar to the Cordyceps that infect insects, Gibellula-infected spiders become “zombies” and will typically position themselves on the undersides of leaves, as the one pictured here was found. Here the fungus finally kills its host and sends out spores that are now nicely positioned to fall upon potential new spider hosts. Back to that bed of white threads. I see one function and two possible origin ideas of these. I believe the function of these is to keep the spider anchored to the leaf so that it does not fall to the ground and greatly hinder the ability of the fungi to infect new hosts. For the potential origin, these could be mycelia of the infecting fungus, or, even better, these could be silk created by the spider, induced by the fungus to anchor itself as the last act before its death.
If you have other ideas as to the potential origin or function of this bead of threads, please let me know!
A Thousand Acres of Silphiums 