Dear Varish,

If we count all the species that humans have described so far, it’s about 2 million. New species get added all the time—about 15,000 of them every year.

But we have no idea how many species we’ve never met. Scientists think there could be 5 million species out there. Or maybe billions.

We’ll only know for sure when we describe all those organisms.

I asked my friend Rich Zack what that means. He’s an insect scientist at Washington State University.

He told me how we identify and name a new species.

Imagine we’re in my backyard collecting insects together. We see a … » More …

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