Anyone can tell you that spiders are able to trap their meals in their sticky silky webs - but there's a bit more to it than that. Spiders are actually able to conduct electricity across the surface of the web, which attracts the potential prey. The research was led by Fritz Vollrath of Oxford University and was published in the journal Naturwissenschaften.
Though arachnology seems to be squarely in the field of biology, understanding the properties of the web required knowledge of physics. The “glue” that makes spider webs sticky is electrostatic and is attracted to any charged particle it comes across. The glue’s static charge actually interferes with the Earth’s natural electric field, so the web is drawn to anything that comes within a few millimeters of it. The team hypothesizes that this slight disturbance could actually serve as a warning to potential prey, as most flying insects are sensitive to varied electrical disturbances.
The web is not just attracted to anything that could be a possible meal; it grabs airborne particulates as well. Some of these can be as innocuous as pollen, but the web is also capable of grabbing pollution particles like pesticides or fertilizers. In fact, researchers may be able to use spider webs in place of environmental sensors in order to investigate local pollution levels without the need for electronic sensors.
Understanding what pollutants are present in an area could allow researchers to investigate how it is affecting insects in the area. High pesticide use could explain a decline of bee populations in certain locations. Additionally, the pollution getting stuck in the web could be harmful to the spider. In order to conserve resources, spiders often ingest their old webs to get the energy to spin a new web. If the web has caught toxic particulates, then the spider will be eating those as well. The research team made the connection to studies in the mid-1900s when spiders were given a variety of drugs to investigate the impact it had on their ability to spin webs.
Future research will test the hypothesis that flying insects can sense the change in Earth’s electrical field around the web, and that they are able to use that feeling to avoid getting eaten. Additionally, the spider webs can also be used to monitor local air quality and pollutant levels over time.
Check out this video from Vollrath's lab of spider silk responding to positive and negative electrodes: