Douglas Fudge: Did you wanna look at some slime?
Christopher Intagliata (tape): I was hoping you would say that.
Fudge: Let me grab a bucket here.
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Intagliata: Of all the things I’ve dreamed of doing in my lifetime, being slimed by a hagfish was not on the list. But maybe it should have been because slime is incredibly cool stuff.
This is Christopher Intagliata, and you’re listening to Scientific American’s Science, Quickly. Today I’m taking you on the first of a three-part journey into the deeply sticky—and fascinating—subject of slime.
Mucus, it turns out, is nothing to sniff at. Wildly complex and just as versatile, this stuff is a true miracle. So grab a tissue and prepare to be surprised by the multitude of species—including us—who are not only alive but also thriving because of mucus.
[CLIP: Opening music]
Intagliata: My fascination with mucus recently took me to Orange, California, where biology professor Douglas Fudge of Chapman University keeps a tank full of hagfish. They're eel-shaped fish and prolific producers of slime.
Intagliata (tape): Smells a little fishy in here.
Fudge: Doesn’t normally smell this fishy.
Intagliata: These fish are ancient. They have no jaws, and these ones have this pinkish-gray skin that hangs on them loosely, like the skin of a hairless cat.
And slime is their superpower. Sharks will bite them—and choke on gill-clogging slime.
After a little fishing around in the tank ...
Fudge: You’ve probably figured out by now, hagfish are escape artists.
Intagliata: We’ve got a hagfish in a bucket, and Douglas gives me my cue—to pretend I'm a shark, basically.
Fudge: Pretend like you're a predator who's trying to take a bite, but do it with your hand ...
Intagliata (tape): It’s not gonna bite me, right?
Fudge: It will not bite you.
Intagliata: I’m still leery of sticking my hand in the bucket and pinching this thing, but I do—gently—and all of a sudden ...
Fudge: And remember ...
Intagliata (tape): Ahh!
Fudge: You barely touched it, and it's ...
Intagliata (tape): All right, my hand is covered in goo now.
Fudge: All right, I’m gonna help you out.
Intagliata (tape): Whoa. Oh, my gosh, the whole bucket is, like ...
Intagliata: I get slimed—with drippy, gooey, alien-caliber slime.
But it's not quite like snot. Hagfish slime is a blend of mucus, seawater and silklike threads, which makes it behave in some really strange ways.
Fudge: As material scientists, even we struggle with how to define it. And that’s, it’s interesting because everyone is surprised by hagfish slime. And I’ve thought a lot about that: Like, what is it that is so shocking about it? Like, what are the expectations that are being shattered when people see the properties of this stuff?
Intagliata: It looks just like water when it’s in a beaker, but when Douglas pinches the surface, he can lift the whole thing out. It sticks together like a bag of water. It’s just really, really weird.
Fudge: You know, there are no liquids that can do that.
Intagliata (tape): If you could turn this into a kids’ toy, I think you might be a billionaire.
Fudge: Yeah, I think we might have to turn our attention to that.
Intagliata: Hagfish slime is incredibly unique in the animal kingdom, because it has those silklike threads.
But regular old mucus is everywhere. And it’s used for so many different things! Just ask the guy who curated what he calls one of the largest libraries of animal mucus on the planet.
Antonio Cerullo: So, hi, Chris. Welcome to the tour of our mucus library. So what we have here is a dedicated –80 degrees Celsius freezer for the storage and handling of animal mucus.
Intagliata: Antonio Cerullo is a slime scientist. He got his Ph.D. at the City University of New York Graduate Center, where he studied slime from all kinds of animals.
And in this freezer, there are samples from more than 20 species, including Douglas’s hagfish, plus 10 different types of salamanders, along with jellyfish, bullfrogs, cows, pigs, snails and lots more.
Cerullo: So here we actually have a couple of exciting mucuses from oysters. So this is the expulsed mucus from Chaetopterus tube worms.... So here we actually have entire pieces of coral.... Embedded is the frozen mucus....
Intagliata: The basic recipe for all this goo is proteins, sugars, salts and water.
Cerullo: And these components come together and form a very large and very chaotic network of interactions to form this entire mucus gel.
Intagliata: That chaotic network of interactions makes mucus a sort of scientific enigma, even to this day. And in Antonio’s view, the only way to truly understand it is to study as many kinds as possible—hence the collection.
Cerullo: Mucus is an entire universe, and there’s so much to be learned about what it is, about how it works.... The wonder of it never stops.... As you keep looking, you keep finding new uses of mucus.
Intagliata: If he sounds like a mucus evangelist, he is. He even practices what he preaches: he smears extracts from snail slime on his face.
Cerullo: I think it has helped my skin glow and be a bit more radiant. I think it does hydrate me.
Intagliata: Lots of other people evidently do, too, because snail mucus is now a billion-dollar industry.
Cerullo: In my personal experience, I prefer to use that at night because it tends to be a bit goopy.
Intagliata: If you spend a little time talking to Antonio, you will soon realize that mucus is a universe—and you'll be regaled with some truly incredible facts about animals deploying mucus in one way or another.
Cerullo: One of the most interesting ones is the velvet worm, which is a creature that has propulsion jets on the side of its head to shoot out strands of slime to fight against predators or to capture prey.
Oh, there is also the red triangle slug, which secretes an extremely strong mucus glue that [will cause] a frog chasing and trying to eat it [to actually] stick to a tree branch containing the mucus and be stuck there for days at a time.
You have the parrotfish, [which] produces a mucus bubble to protect itself while it sleeps.
The echidna, actually, it produces mucus bubbles from its nose to coat its nose ... to cool it down.
You have the hippopotamus, [which] produces a mucus across its skin that keeps it hydrated when it leaves the water in the hot African heat and also contains UV protective pigments, which acts as a sunblock.
Intagliata: Mucus sunblock! How cool is that? If you're not experiencing mucus envy yet, maybe you should be?
Even so, Antonio says he still gets side-eye when he mentions he has dedicated his scientific career to mucus.
Cerullo: Most people, when you mention mucus, you're met with disgust. But they’re actually some of the most fascinating materials on Earth and some of the most important, so we hope that in our work, we can convince people that mucus is not gross but is rather beautiful and has such great importance out there in nature and is really just such an elegant material made of so many components that are all choreographed to have these very defined and dynamic roles.
Intagliata (tape): So you think it gets kind of a bad rap?
Cerullo: Absolutely. Usually by the end of a discussion about mucus, my audience or my conversation partner really is convinced that mucus is amazing.
[CLIP: End music]
Intagliata: In the next episode, we’re gonna talk about the amazing things mucus does for us in our own body—and some early medical experiments that, yes, involved drinking mucus milkshakes.
Katharina Ribbeck: What they found was one good vehicle for mucus delivery is milk or eggnog or liquids that are creamy.... And then the more undesirable aspects of mucus are disguised.
Intagliata: Hungry yet? Tune in next time.
Science, Quickly is produced by Jeff DelViscio, Rachel Feltman and Kelso Harper and edited by Madison Goldberg, Elah Feder and Alexa Lim.
Like and subscribe wherever you get your podcasts. And for more science news, go to ScientificAmerican.com.
For Science, Quickly, I’m Christopher Intagliata.
