While all documented spider species that are living today produce silk, not all spiders spin webs; instead, some spider species use their silk solely to construct cocoons for their developing offspring, and this is only one of many ways in which spiders use silk. In addition to silk, venom is also produced by all spider species, but this claim is disputed by a minority of individuals. Unfortunately, all spider species also possess fangs, but the fangs of some species are too small to penetrate human skin. Nearly all documented North American spider species are capable of inflicting bites that puncture human skin, and these bites inject venom into the bloodstream. Spiders from the Uliboridae family are an exception in this regard, as they lack venom glands as well as the ducts necessary for delivering venom beneath the surface of skin. All other spider species possess both of these physiological mechanisms. Luckily, very few spider species are capable of inflicting medically significant bites to humans and even common pets. Of course, black widows and recluse spiders, particularly the brown recluse, sometimes inflict bites that have serious medical consequences, including necrotizing bite wounds and even death, but such cases are rare. However, while the vast majority of spiders inflict harmless bites, that cause minimal, if any sensation of pain, just about every spider species can inflict a bite that can lead to infection.
When an infection occurs in response to a bite inflicted by an otherwise harmless species, the infection is known as a “secondary infection.” It may surprise many people to know that researchers are not exactly sure how a spider species is able to cause a secondary infection with their bite. Many people assume that secondary infections of this sort result from bacteria already present on an offending spider’s fangs, but most sources claim that secondary infections cannot result from skin being punctured by bacteria-contaminated fangs. One particular study showed that 36 percent of Brazillian recluse spiders had traces of gangrene-causing Clostridium perfringens bacteria on their fangs, and it was also found that 16 percent of these spiders passed this necrotizing bacteria through their fangs. However, 0 percent of these spiders had the necrotizing bacteria within their venom glands. Unsurprisingly, the results of this study puzzle researchers, but the study has not yet been replicated in any North American spider species. Some researchers believe that the brown recluse of North America acquires potentially deadly bacteria by feeding on the decaying corpses of insects, which would explain why so many brown recluse bite wounds develop tissue necrosis. This theory is hotly debated in the scientific community, and no satisfying explanation has yet been provided to explain why some spider bite wounds develop secondary infections.
Have you ever developed a skin infection that you believe resulted from a spider bite?