Did you know that as a living organism, you shed genetic material called DNA? Although you usually can’t see it stuck anywhere, you’ve probably left DNA on everything that you’ve touched! This is also true of every other living thing—from bats to birds to bumblebees, there’s lots of DNA floating around out there.
Environmental DNA, or eDNA, is the genetic material that living things shed into the environment around them through their skin, hair cells, poop, or other bodily residues. It can be sampled from water, soil, petals, air, and apparently, spiderwebs. Sampling this genetic material can tell us about the different species that live in or frequent a specific area.
Because spiderwebs are sticky, eDNA particles can easily get caught in them. Scientists realized that if we sample these webs, we are likely to see what wildlife has come in contact with them. We can even see the wildlife that’s been in the area but hasn’t necessarily touched the web, because gusts of wind can carry eDNA particles into webs. They’re like a piece of tape hanging in the wind. Isn’t that cool?
This is how the use of spiderwebs for eDNA collection was born. It’s still a new concept, but Conservation Biology Postdoctoral Researcher Dr. Rachel Larson and Conservation Biology Community Engagement Apprentice AJ Feller have taken on this innovative method in collaboration with the Invertebrate Zoology team to learn more about wildlife in our local canyons and neighborhoods. We were introduced to this methodology by Dr. Demian Willette of Loyola Marymount University, who is a trailblazer in spiderweb eDNA and has helped make this project possible.
Collecting eDNA data can tell us what may be living near the sampled location. This project is specifically focusing on capturing data from Olivia Canyon and Chollas Radio Open Space Preserve to learn about the species that frequent or live in those urban canyons.
Sometimes it’s hard to observe animals that are tiny, active at weird times, or simply not easily spotted through visual surveys. The great thing about collecting eDNA is that the spiderwebs basically do the work for us.
This approach can help us complement our scientists’ traditional surveys to build more complete species lists for our canyon habitats. Once we know what animals live here, we can help protect them. This information can help us better understand how wildlife may be interacting with our neighborhoods and how they may be impacted by urban development. And since spiderwebs are everywhere, we can get data from all over. It's like having a ton of tiny cameras all around the city, capturing data 24/7. Thanks, spiders!
To help us collect samples from these canyons and neighborhoods, we recruited you: our fellow community science fanatics! The team held "Canyon Spider Blitz" days led by AJ and Rachel, where they met at the two canyons and trained interested community members on how to sample spiderwebs so they could do it in their own backyards.
For the sampling process, participants were first instructed to locate and take a picture of the web in their yard (and the spider, if present). This allowed us to keep track of how old the web was and what type of spider lived in it. Then, they collected the web by gently swirling it around a toothpick, similar to collecting cotton candy or twirling spaghetti around a fork. Spiders were left behind to make more webs (and more data for us)!
After two weeks of collecting, the samples were sent to the Willette Lab, where Demian and his team sequenced the eDNA and sent us the results.
Involving the community in this project is helping us understand how the species found in urban canyons may extend into the surrounding neighborhoods. Each person that collected spiderweb data got their results back, so they got to learn more about what wildlife may be living nearby or visiting their neighborhood.
Thanks to our research partners, the spiders, we were able to catch eDNA from invertebrates, mammals, birds, and more! The eDNA analysis detected 50 unique species from our list of “most wanted” wildlife, with 20 of these being insects (two of which were parasites)—pretty cool.
As we hoped, we found hard-to-detect species like the garden slender salamander (Batrachoseps major), the gray fox (Urocyon cinereoargenteus), and the lesser nighthawk (Chordeiles acutipennis). We also learned that the species lists were similar for both the neighborhoods and canyons, with a few animals only being found in the neighborhoods, like the cabbage white moth (Pieris rapae).
We’re working on refining these results to get a more detailed list of all the species that these webs captured. This project was just one step in our journey of understanding and helping protect wildlife in our shared neighborhoods and canyons. Our goal is to be able to continue using this method to sample even more neighborhoods and collaborating with spiders to learn more about the wildlife we coexist with.
Dr. Demian Willette training staff from The Nat learning how to properly sample spiderweb eDNA.
Dr. Demian Willette demonstrating how to properly collect a spiderweb and secure it in a sampling tube.
Dr. Rachel Larson's collected spiderweb sample on a toothpick.
The Conservation Biology team’s set up for the second Spider Blitz Day at Olivia Canyon.
Community participant from the Canyon Spider Blitz days, hard at work collecting spiderweb samples from vegetation in Olivia Canyon.
Community participant collecting spiderwebs from Chollas Radio Open Space Preserve.
Community participants at the Spider Blitz Day in Chollas Open Space Preserve, photographing a web before collecting it for a sample.
Posted by Janae Pabon on October 7, 2025
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