Emily: We're back here in the Insect Division with Associate Curator Petra Sierwald.

Petra: Hi Emily.

Emily: And we're here to talk about millipedes today.

Petra: So millipedes belong to the large class of Myriapods "having many legs." The big ones that you know are centipedes, having fewer legs than millipedes in general. Having about one leg pair per body ring, whereas millipedes have two leg pairs per body ring, so they're just leggier.

Emily: So is there any credibility to centipedes having hundred legs and millipedes having a thousand legs?

Petra: No. Centipedes just have fewer legs and I think that's what the name implies. Centipedes, millipedes all actually have completely different lifestyles. Centipedes slither sideways like sort of in the movement like snakes when they move. They are predators and their front, the first pair of legs, is modified to poison glands and they are ill tempered and they will bite if they are sufficiently annoyed.

Millipedes on the other hand are peaceful vegetarians. They really like rotting vegetation I mean rotting leaves is kind of the best thing in the world. They have a lot of legs. Using their legs often to push basically their hard sclaratized (? 1:27) head into the soil, pushing with all legs in the back and kind of drilling into the soil. Kind of like earth worms do, providing the soil with spaces for air and where water can travel. But their main job is munch munchers. Waste management.

Emily: So they're essentially recyclers, they're like cows.

Petra: Yeah.

Emily: So are all of those legs in millipedes used for for locomoting?

Pera: Largely yes, except that the front legs in males, and especially the legs around the 7th ring are modified for again, sperm transfer organs. These are copulatory organs, secondary organs, highly complex, again we can distinguish every millipede species on the planet by the copulatory organs. In some of these, like these adorable giant Pill millipedes have legs at the end of the body modified to sperm transfer copulatory organs, also clasper organs to hold onto the female. We know almost nothing about the female receptive organ.

One of my current kind of major mega project is a morphological atlas covering all the 16 orders of millipedes.

Emily: Sure, I was going to ask you how many species do you hypothesize exist?

Petra: At this point, um I'm keeping a catalog actually a global catalog of millipedes species and I have 13 about 13 thousand records.

Emily: So that's more than all of the birds and mammals combined?

Petra: Yeah, it is we almost. Yes.

Emily: For as ecologically important as they are, I mean essentially they're cycling this undergrowth, they're facilitating the health of these forests and ecosystems, it seems important to me that we have more people studying them.

Petra: Oh I fully agree. (Laughter)

Emily: I'm just tryna like inspire the next generation of, ah, millipede experts.

Petra: Well, part of the things that we have when we have a problem with millipedes is that we don't have some of the basic research infrastructure in place. And that is like a comprehensive morphological atlas, so that if you find a new species you can go and find images and actually compare what you see to what others have already observed.

Emily: Is there any sense of urgency behind needing to describe and put this information out there like our millipedes in danger, of habitat loss...

Petra: Good question.

Emily: and if they are what would happen to these other forest ecosystems?

Petra: I'm afraid that millipedes are more endangered than we think because they are cryptic we often don't see them. Millipedes lay their eggs in the soil if we clear-cut areas of forest and the soil erodes away, the millipede eggs are gone as well. And if you then reforest, nobody's eating the rotting leaves. And so, deciduous forests could drown in their own leaf litter.

Emily: Well that seems kind of unfortunate to me because if you look at the history of millipedes on earth millipedes have been around as long as there has been plant matter.

Petra: Yep, 420 million years I think is the oldest fossil of a land living millipede.

Emily: So the first animals to get on land and to breathe air... were millipedes?

Petra: Yes. Were millipedes? As far as we know, yes. And it makes sense because that was the first food that was available on land.

There are some millipedes actually that produce light. And they're polydesmid millipedes. We have experimented here just with florescent with using UV light, shining them on millipedes and certain parts then fluoresce and it makes it easier for us to make digital images of the various body parts. And we don't have to coat the specimens with gold, what we have to do when we go to the SCM.

So this is "Big Mama" I would call her Big Mama. This is a native North American millipede. Narceus americanus. And we have a female here. We know that she's, she's good size, so she will be in forests out here in southern Illinois. You can see their antenna. Her antennae are now coming out and she's kind of investigating, tasting the sort of the substrate.

Here you can see the movement of the legs I think how it goes in waves, very coordinated waves, through her body.

Emily: Wow yeah.

Petra: So we haven't really annoyed her that much otherwise she would have sprayed us with her repugnatory secretions, most millipedes have these secretions. In some of the polydesmids they actually maybe cyanide.

Emily: Really? So she, she can excrete cyanide?

Petra: She, this particular one cannot but millipedes of the large order Polydesmida can.

Emily: It's like a little, she's like a little Velcro.

Petra: Yes, she has claws at the end. I mean "claws," they cannot penetrate our skin, but she has claws at the end of the feet and so that she could climb kind of tree bark and so on.

Emily: She's trying to bite me.

Petra: Is she trying to take a little nip out of you?

Emily: Yeah.

Petra: I mean she can't really pierce the skin.

Emily: No, it's just like a little nip.

Petra: So you see the dark spots that are sort of her eye pads, her eye areas She has clusters of individual eyes in these two eyes patches.

Emily: Yeah, they kind look like big puppy dog eyes but you mentioned to me earlier that they're-

Petra: They don't see very well.

Emily: Yeah.

Petra: But the species is rather common here.

Emily: It just tickles.

(Laughter)

[Brain scoop outro]

Emily: It still has brains on it.