Citizen scientists are mapping the global food web one feeding photo at a time

A simple question sits at the heart of ecology: who eats whom? Despite centuries of natural history research, scientists still lack complete answers for most of the planet’s species. Feeding relationships are scattered across thousands of academic papers, field notes and museum records, making it extraordinarily difficult to build a coherent picture of how the world’s food web fits together. Now an interdisciplinary team led by researchers at North Carolina State University has taken a decisive step toward solving that problem, and they have done it by inviting the public to help. The team has launched an open-source platform called Who Eats Whom, a searchable online database that compiles observations of trophic interactions — the predator-prey relationships that connect every living organism — contributed by citizen scientists around the globe.

The project taps into iNaturalist, one of the world’s largest biodiversity platforms, where members of the public upload photos, video and audio recordings of the organisms they encounter. While iNaturalist has long been used to map where species live, the new initiative extends its power to a different layer of ecological information: what those species are actually doing when they encounter one another. Users of the platform can now explicitly tag both predator and prey within a single photograph or video, capturing a feeding interaction at the moment it happens. The predator in question may be a lion taking down an antelope or a caterpillar munching on a garden leaf; the database treats both interactions as equally valuable data points in the planetary food web.

Bradley Allf, corresponding author of the paper describing the project and currently a postdoctoral researcher at Colorado State University, began the work while a graduate student at North Carolina State University. He explains that knowledge of what organisms eat remains fundamentally incomplete and fragmented across the academic literature. iNaturalist, he notes, has already proven its worth in documenting which organisms live in different locations, and this project extends that success to feeding relationships. The result is a publicly available website, who eats whom dot org, where anyone can explore recorded trophic interactions through an easily searchable interface. What began as an effort to consolidate scattered knowledge has quickly become one of the largest structured datasets of its kind.

The numbers are already striking. To date, the Who Eats Whom project has logged approximately seventeen thousand observations of trophic interactions involving roughly five thousand seven hundred species. These records have come from around two thousand observers based in more than one hundred countries, spanning ecosystems from tropical forests to suburban backyards. Each observation represents a moment when a person witnessed and documented one organism consuming another, creating a verifiable record that researchers can analyze, visualize and cross-reference with existing scientific literature. In aggregate, these individual moments begin to sketch the outline of a global food web, a planetary-scale network of feeding dependencies that has never been mapped at this level of public participation.

Aditi Mallavarapu, co-author of the paper and an assistant professor of computer science at NC State, approached the project from the perspective of human-computer interaction and tool design. Her interest, she says, lies in building usable interactive tools and learning environments, and the food web presented an irresistibly complex system to work with. The design goals were explicit: the site had to be usable, visually engaging and ethically responsible in the way it handled data contributed by citizen scientists. Mallavarapu emphasizes that the platform is intended to serve both researchers and the general public, helping each group grasp feeding relationships that are too numerous and too intricate to be understood through static tables or technical papers alone.

One of the most revealing early findings concerns what motivates participants. Mallavarapu observes that public interest extends well beyond charismatic predators such as lions and wolves. Contributors are documenting smaller, quieter trophic relationships, such as the insects that feed on persimmon leaves, and are using the site to explore interactions tied to their personal passions and local environments. This breadth of engagement matters scientifically. Ecological research has historically skewed toward large, photogenic species, leaving the vast majority of feeding interactions — particularly those involving invertebrates, plants and microbes — poorly documented. A platform driven by thousands of curious amateurs naturally fills some of those gaps, recording interactions that professional ecologists would rarely have the time or funding to chase.

From a technical standpoint, the database opens several promising research directions. Allf notes that the team can use Who Eats Whom to identify novel trophic relationships that have not yet appeared in the academic literature, then contribute those findings formally to scientific publications. The long-term ambition is for the platform to function as a parallel database that complements the peer-reviewed literature, compiling as much feeding information as possible into a single, accessible location. Because observations are time-stamped and geolocated through iNaturalist, the dataset also carries temporal and spatial dimensions that static literature reviews cannot match, potentially allowing scientists to track how feeding relationships shift across seasons, habitats and years.

Visualization is central to that ambition, and it is where Mallavarapu’s team is investing heavily. She describes a planned visual representation of this planetary-scale food web, designed to capture how trophic interactions relate to one another and how those relationships change over time. A simple version of the interface is already live, but the developers are building richer features that will let users explore feeding patterns and pose practical, personal questions — such as what to plant in a North Carolina garden to attract hummingbirds. That framing reveals the project’s dual identity: it is simultaneously a serious scientific database and an invitation for ordinary people to see themselves as participants in the ecological networks surrounding them.

Data quality remains a central challenge for any citizen science effort, and the team is developing tools specifically to validate submissions tagged on iNaturalist. Verification workflows will help ensure that predator and prey identifications are accurate and that interactions are recorded consistently, protecting the database’s scientific value as it scales. Beyond research, the project has an educational mission. The team has already created educational games built on the database, aimed at helping children understand the food web and the interdependencies it captures, with plans to expand that work if additional funding can be secured. The project was developed with substantial contributions from NC State students, including Maithili Bhoop, Adam Biscoe, Surabhi Nair and Lavanya Middha, alongside the thousands of iNaturalist users whose field observations make the entire enterprise possible.

The underlying research, titled Who Eats Whom? A global food web derived from citizen science, was published on September 22 in the open-access journal PLOS Biology. Senior author is Rob Dunn, a professor in NC State’s College of Agriculture and Life Sciences; additional authors include Nikhil Vasudeva, a former NC State undergraduate, and David Kikuchi, an assistant professor of integrative biology at Oregon State University. The researchers report no conflicts of interest. As the database grows, its creators hope it will transform not only how scientists study food webs but also how the public understands them — turning every hiker, gardener and backyard naturalist into a node in a worldwide effort to document the fundamental question of ecology: what eats what, and why it matters for the living planet.

Subject of Research: A citizen science platform that compiles global predator-prey interaction data from iNaturalist to map the planetary food web.

Article Title: How amateur naturalists are helping scientists track what everything eats

Article References: How amateur naturalists are helping scientists track what everything eats. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: citizen science, food web, iNaturalist, trophic interactions, ecology, biodiversity, Who Eats Whom, open-source database, PLOS Biology, public engagement, predator-prey relationships, data visualization