Innovative study reveals how arachnids tune out noises
Humans have a toolkit of strategies for dealing with environmental noise: Headphones, white noise, soundproofing materials and more drown out traffic, construction and airplanes.
Husker research suggests that animals, too, have methods for managing soundscape clutter. Biologists Eileen Hebets and Brandi Pessman published one of the first studies showing that one type of animal – the funnel-weaving spider – can change how it receives sound when faced with local, human-generated noise.
The duo demonstrated the spiders’ webs transmit vibrations differently in response to noise, suggesting an intentional attempt to manage sound. The webs also differed depending on the architect’s background.
“One of the most interesting things we found is that urban and rural spiders are reacting differently when they’re put into a noisy environment,” said Pessman, lead author who conducted the research as a Husker graduate student in biological sciences. “This means that spiders with different experiences with noise – whether they themselves experienced it or their mothers passed it down to them across generations – respond differently.”
Animals’ adjustments in producing sound amid environmental noise are well established, but discerning reception is difficult because it requires studying internal sensory structures. Spiders have an external sensory mechanism – their web – a unique gateway for research.
“This study really highlights the role of receivers in overcoming environmental noise,” said Hebets, George Holmes Professor of Biological Sciences. “It opens up entirely new avenues of research … Even without being able to go into the nervous system, other people can start looking at ways that receivers might be adjusting to increase the relevant signal-to-noise ratio.”
Hebets and Pessman focused on vibratory noise, the spiders’ dominant form of communication. The researchers hypothesized the spiders build webs to guard against human-made vibrations, which overlap their communication frequency range.
The team exposed the spiders to quiet or loud vibratory noise during web construction. With loud noise, urban spiders – who are accustomed to high-amplitude sound – built webs that quieted their environment, likely to avoid excessive stimulation, protect their hearing and accurately detect prey.
Rural spiders faced with loud noise tuned their webs to enhance incoming vibrations at a particular frequency – likely a means of “turning up” the volume to amplify certain signals.
National Science Foundation funding supported this work, which was published in Current Biology.
Brandi Pessman (left) and Eileen Hebets