[Emily Graslie]: This episode is brought to you by a collaboration between the Denver Museum of Nature and Science and the Field Muesum in Chicago, Illinois.

[intro]

E: Back in 2004, at the ripe age of 14, I received an e-mail that looked something like this. It was a picture of two massive nightmarish creatures with enormous fangs and humongous legs.  They appeared to each be as big as a grown man's thigh and looked like they could take off your finger.  The description with the images mentioned that they have a quote "vertical leap that would make a pro basketball player weep with envy" and that they need to jump high enough to jump onto a camel and suck out its juices and maybe even lay its eggs in its stomach.

The thing is, most of that isn't true.  I mean, the animals are, it's just that the forced perspective makes them look huge.  The biggest ones are 6-8 inches, they're completely non-venomous, can't jump like pro basketball players, and even though they can run pretty fast, they still can't outrun you.

These are camel spiders, and there are more than 1100 known species.  They live in deserts all across the world with the exception of Australia and Antarctica, and the oldest known species date back to 300 million years ago.  It was around during the Carboniferous period and roamed the planet some 60 million years before the dinosaurs.

So even though these guys are super-abundant and have been around for a really long time, there's still a bunch we don't know about them, which is why I came here to the Denver Museum of Nature and Science to talk to Dr. Paula Cushing. She's been studying these guys for nearly 17 years.

Paula is an evolutionary biologist and curator of invertebrate zoology. Her research focuses on arachnids - a group of animals that include spiders and scorpions - but her specialty is in camel spiders. She's one of maybe five scientists in the world who is regularly publishing new discoveries on these relatively mysterious creatures. So, we went to her lab to learn more about her work.

E: So, why don't more people study them?

P: So, they're really hard to study: they're hard to catch when you're in the field, they're really hard to keep alive in the lab - I started calling them the "spawn of Satan," [E chuckles] because they seem to appear-, you're out there in the desert, they peer outta nowhere, they disappear, they run like the wind, you try to catch them, you can't catch them, they're just-, it's like a love-hate relationship that I have with these things.

E: So, are they venomous? Are they toxic at all?

P: No, so they have no venom. They act like they could take you down [E laughs], but they can't, so they're really pretty harmless. When I catch them, when I grab one by my hand, the big species - like what you're seeing under the microscope - they'll give you a little nip, and you can feel it. And I scream like a girl when they bite me, but they're not strong enough to break your skin. Our skin is tougher than we think.

E: Can you just tell us a little bit about their interesting anatomy?

P: Sure. So one of the most remarkable things about these arachnids is their enormous jaws. Jaws of arachnids are called "chelicerae" [slide: "Noun: The mouthparts of the chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders."]. And they can move their jaws both this say [motions horizontal scissoring motion] and this way [motions vertical scissoring motion].

E: So, side-to-side and up and down.

P: Side-to-side and up and down, yes. And they'll grab the prey using their legs and their front appendages are called "pedipalps," but they bring that insect close to their jaws, to the chelicerae, and then they just start tearing it apart.

But they can't chew. So what they do is they-, as with almost all arachnids, the vomit digestive enzymes onto the body of the prey. The digestive enzymes break down the muscles and the tissue, and then, like with other arachnids, they have a muscular stomach, and they just suck in that pre-liquified, predigested meal.

E: Oh, how appetizing.

P: Yes. And with males in the family that I study-,I study animals in the family "Eremobatidae," and in that family, the males have no teeth on that upper jaw of the chelicerae, whereas the females, she has teeth on both the upper and lower jaw.

And the reason there's a difference - when they get ready to mate with the females the male solifugae - the male camel spider - he find the female out there, he rushes at her, he gras her around the middle of her body, and as soon as he grabs her, if she's receptive and ready to mate, for some reason, she goes completely quiescent - it's like she goes into a trance.

And then what the male does is he moves his jaws down to her genital opening on the underside of her abdomen and he sticks his jaws into her genital opening and he starts to chew. [E cringes] I know!

The male exudes from his genital opening the sperm packet, and he'll pull his jaws out, he'll move his body up, he'll deposit his sperm packet onto her genital opening, and then he bops back down, and then he sticks that sperm packet into her again using his jaws, and then she starts to wake up.

He books it out of there as fast as he can, because at that point, anything goes: she could eat him, he could eat her, they could both run away, they're -

E: Wow.

P: Yeah.

E: I mean, that sounds like a couple dates I've been on. [P laughs] So, why does it seem like they chase after you?

P: So there are stories of soldiers in Iraq and Afghanistan who have been stationed there who claim that they're running after them, they're chasing then down in the desert, and I think what's happening is as the soldiers are working in the desert, they're basically uncovering the daytime burrows of these animals. And when they're disturbed during the day, they don't like it - they don't like the sun, they're trying to seek out shade. So, we think what they're doing is they're chasing after the shadow of the soldier, and by doing so, by running after the shadow, they're essentially looking like they're running after the soldier.

They have this remarkable ability to maintain very high activity rates for very long periods of time. They have tracheal tubes kinda like insects do. So those tracheal tubes are picking oxygen up through little holes in the exoskeleton into their body and are transporting that oxygen very efficiently all through the tissue of the body.

E: Wow. So as terrifying as they might seem, they're pretty harmless.

P: They're pretty harmless.

E: Yeah. We don't know enough about them.

P: Yeah. What we do know is they're important predators in very dry, xeric desert environments. And deserts worldwide are habitats that are at risk from agriculture, from irrigation, from developments... And so, these top predators - like the solifuges, like scorpions - they're important in both controlling the insect populations that live in the desert, they're also important food!

So, desert-adaped birds, mammals, reptiles are using solifuges as an important food item. It's important for us to understand, I think, more about the biology of all organisms on earth. I mean, we have one planet that we share with millions of species, and we know so little about the biology of our neighboring species on this planet. Anybody can make discoveries about them. I mean, there's so much left to know about camel spiders, so that's the really satisfying part of studying these animals.

E: Yeah. I can get behind that.

P: Yeah, I think everybody should get behind that.

E: Yeah! Camel spiders!

P: Yes! Arachnids, yes!

E: Yes!

[outro, music ends]

E: It still has brains on it.