We share our planet with maybe 10 million species of plants, animals, birds, fish, fungi and bugs. And to help identify them, millions of people are using a free phone app. "Currently we have about six million people using the platform every month," said Scott Loarie, the executive director of , a nonprofit.

Has anyone made a cool discovery using the app? "It happens all the time," Loarie said. "Almost every month we get a new species described.

One of his favorites stories involved someone in the Andes whose cabin was invaded by a weasel: "He grabs his camera. The first-ever photographs of these species, and they happen to be sitting on a toilet in this cabin. I'm very proud to say that #ToiletWeasel was trending on Twitter after that!" 

But it turns out that this app has a stealth function: It can share your photos with scientists. "It's not just a photo. It has a date, it has a location," said Loarie. "It turns out that most data for most species on the planet now is coming from this little app."

So far, iNaturalist fans have made 300 million sightings in all 197 countries, providing data on hundreds of thousands of species a year. They let scientists see what's happening to life on Earth.

The data can track the movements of invasive species over time, like the lanternfly, which came from China and is now taking over the U.S. East Coast.

But it's not just about species moving. It's also about species disappearing. "The best predictions now are that we're going to lose about one in three by the end of the century," Loarie said.

But should we care about obscure species that we've never heard about in the first place?

"An analogy I like is that the Earth is this plane, that we're in mid-flight," Loarie replied. "Every time a species goes extinct, that's like us popping a rivet off. So, at some point the whole wing is gonna fall off. But we don't exactly know which rivet, which species extinction is gonna drive that. So, the first thing we need to do is stop popping rivets off."

This app is especially fun to use with other people. 

We attended a "BioBlitz," a friendly timed competition, where teams set out to see who could find the most species in the span of one hour. This one was being hosted by someone who knows a lot about nature: Martha Stewart, at her home in Bedford, New York.

In one hour, our little group had identified 458 different species. Loarie reviewed some of the findings with Stewart: "Beautiful little moth right here. This little assassin bug. Different kinds of snails and butterflies. Each one of these observations will give us a snapshot of all the different plants and animals that are here, and the kind of habitat that you've provided for all these species on your farm."

For Loarie, it never gets old. "People go like, 'Wow, I'm actually part of the solution. By me taking this photo, I'm helping science. I'm helping us protect these species that I share the planet with.'"

Martha Stewart would agree – though maybe she didn't need the app, because she knew every bug and leaf. "But that's because I've lived here now for more than 20 years," she laughed. "And yet, the app really teaches me the botanical names, the biological names of the bugs and the butterflies. I learn something new every day!"

     
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Story produced by Robbyn McFadden. Editor: Chad Cardin.