Hi, I'm Wendy Zuckerman and you're listening to Science Versus from Gimlet.

On today's show, Butterflies that seem to be sucking on eyeballs.

We heard about it and wanted to tell you all about it.

Okay, so this all started the other day when I hopped on the phone with Chandray Mitra.

She's an assistant professor of biology at North Central College in Illinois.

And Chandray told me that she'd seen these pictures where it looked like butterflies were feeding on the eyes of other animals.

Animals like turtles.

Yeah, you usually see them sort of like mobbing the turtle's head and it's like poor turtle.

Oh my god, looking it up right now.

Oh, go, go, go.

Oh, turtle.

Because it's really getting mobbed by the butterflies.

I mean, the first time I saw those pictures, I was like, wow, this is incredible.

And I was like, why?

Why are they going off to the eyes?

Well, we think it's the tears, right? Coming from the eyes.

Wait, so they're like sucking the tears from the turtle?

Uh-huh.

Studies have found that butterflies want all these tears for one main reason.

They're full of salt.

And butterflies need that salt to help their nerves and muscles work.

Butterflies also slap up salt from mud puddles, which is why this is known as paddling.

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