IRA FLATOW, HOST:
And now for our Video Pick of the Week. Flora's still here and positioned perfectly to take us on a safari.
FLORA LICHTMAN, BYLINE: We're still on safari.
FLATOW: We're still on safari.
LICHTMAN: The safari continues, this time to slightly larger organisms. See if you can see with your naked eye, and maybe in your own backyard. These guys are glow-in-the-dark - I have you already, don't I?
LICHTMAN: Millipedes - which, I didn't know - let me - can I tell you the story of how this came about?
LICHTMAN: This is one of these really - I - one of my favorite types of videos, because it came from one of our listeners.
LICHTMAN: Chris Lavin wrote me an email a few weeks ago and said, Flora, I was walking home, and I stumbled upon something amazing. And I click the video link, and there's this bright, glowing blue millipede, and then she told her sons, who were teenagers, and they collected, like, dozens of them.
LICHTMAN: So the next video, there's many of them in a bowl.
LICHTMAN: And she said, you know, I really want to know what's going on. And, you know, we run with so many scientists here on SCIENCE FRIDAY.
FLATOW: Right. Of course. That's it. This is the challenge for us.
LICHTMAN: So we found the world expert on glowing millipedes, Paul Marek.
FLATOW: There has to be one, right?
LICHTMAN: Of course.
LICHTMAN: This is science.
LICHTMAN: So he's at the University of Arizona. He's an entomologist. And I asked him to take a look at this video. And indeed, they are millipedes, and apparently, there's this whole family of millipedes that will fluoresce. So that means under UV light, they'll, you know, turn a color, like the black light in your house.
FLATOW: Right, they glow.
LICHTMAN: So they glow. But even more amazing, I thought, was that there are also millipedes - only in these certain mountain ranges in California - that will bioluminesce. So they'll spontaneously generate their own light through a chemical reaction in their body. You don't need the UV light, in other words, like a firefly...
LICHTMAN: ...or these deep-sea creatures. And he has a lot of video of these guys. And the big mystery is, you know, why are they doing this, because...
FLATOW: Got to be some advantage, right?
LICHTMAN: There has to be some - well, that's the thought, at least for the bi-luminescence millipedes. So they have this amazing study that's totally worth looking at on our website. It includes millipedes on leashes...
FLATOW: It's a millipede on a leash. Now, you've seen dogs, cats, a ferret, maybe, something. You've never seen a millipede...
LICHTMAN: I had never seen a millipede on a leash.
FLATOW: ...on a leash. And they actually left them on the leashes so they wouldn't go away some place. They needed them to stay there, right?
LICHTMAN: That's right.
FLATOW: And why do they have so many legs, a millipede?
LICHTMAN: Well, Ira, it's funny you should ask. We have the answer for you.
PAUL MAREK: The idea is that they added all these legs onto their body in order to be better burrowers. They live under logs and in decaying vegetation. And by being able to truck through the soil, it seems to have had an advantage in their evolutionary history. And it's pretty noticeable, because all of these millipedes have many legs. And the leggiest one actually has 750.
LICHTMAN: I - you know, I always thought it was 1,000.
MAREK: Oh, yeah. It's actually - so a millipede actually misnomer.
FLATOW: Wow. This is New York. So for you, it's 750.
LICHTMAN: Right. Anyway, go check it out on our website, sciencefriday.com.
FLATOW: It's up there on the Video Pick of the Week, up there on the left side, the glowing millipedes. Thank you, Flora.
LICHTMAN: Thanks, Ira. Transcript provided by NPR, Copyright National Public Radio.