An Aquatic Charismatic Creature Showdown: Mantis Shrimp Vs. Hellbender

IRA FLATOW: This is Science Friday. I’m Ira Flatow. And it’s the moment you’ve all been waiting for. It’s time for our Charismatic Creature Carnival.

Joining me today, as always, is our Charismatic Creature Correspondent, SciFri Producer Kathleen Davis. Hi, Kathleen.

KATHLEEN DAVIS: Hey, Ira. I’m very excited to be here.

IRA FLATOW: Me, too. So we’re kicking off the Carnival today. Tell us a bit about what we’ve got in store.

KATHLEEN DAVIS: So over the next three weeks, we are shining a spotlight on six audience-suggested charismatic creatures. And by charismatic we mean a creature that’s overlooked or unfairly maligned by the general public. That once you look a little bit closer, it has an undeniable charm to it.

IRA FLATOW: Hey, that sounds like you’re talking about me there, I think.

KATHLEEN DAVIS: I’m not kidding. Somebody actually did suggest to you as a Charismatic Creature.

IRA FLATOW: Is that right?

KATHLEEN DAVIS: But we had to take you out of the running, unfortunately.

IRA FLATOW: Shucks.

KATHLEEN DAVIS: That also means that undeniably cute creatures, like koalas or pandas or capybaras, they don’t belong here. We’re highlighting animals that you might write off at first, but they deserve a closer look, you could say. And we’re going to do these head-to-head friendly battles between two creatures. Each creature has an expert representative who’s going to try to convince you, and our audience, that their creature is the most charismatic of each round.

We’re going to have a few weeks of voting. And then at the end of the Carnival, we will have our very first true inductee into the Charismatic Creature Corner Hall of Fame.

IRA FLATOW: OK, enough talking. Tell us about how these creatures got chosen.

KATHLEEN DAVIS: Yeah. So we got dozens of really great suggestions from our audience members. And then we had the SciFri staff vote on their favorites, and we were able to narrow them down to six. So, Ira, are you ready to learn what creatures are part of this fall’s Charismatic Creature Carnival?

IRA FLATOW: More than ready. Hit me.

KATHLEEN DAVIS: OK. So you’re six possible champions are the aye-aye, the hellbender, the mantis shrimp, the opossum, the pigeon, and the shoebill stork.

IRA FLATOW: OK. OK. Those are some great candidates. Let’s kick off our first match-up. We’re going to have one per week for three weeks. So which creatures are we going to hear about today?

KATHLEEN DAVIS: OK. So for our first match-up today we are heading into the water. So I would like a drum roll, please.

[DRUM ROLL]

In one corner, we’ve got the mantis shrimp. This creature was suggested by Garrison, from Charlotte, North Carolina. He left us this message on our SciFri VoxPop app:

GARRISON: I’d like to nominate the mantis shrimp for the Charismatic Creature Carnival. The mantis shrimp has a few features that make it worthy. For one, it’s got an incredibly powerful punch, capable of producing heat and light. It’s got some of the most complex eyes in the animal kingdom. And the charismatic bow on top is that it is certainly colorful enough to attend a carnival in style.

KATHLEEN DAVIS: That’s a pretty good argument.

IRA FLATOW: Pretty good.

KATHLEEN DAVIS: And representing the mantis shrimp in our Charismatic Creature Carnival is Jason Dinh, PhD candidate in biology at Duke University, in Durham, North Carolina. Welcome, Jason.

JASON DINH: Thanks for having me.

KATHLEEN DAVIS: And in the other corner, we’ve got the hellbender salamander. This creature was suggested by listener Timothy, from Pittsburgh, Pennsylvania, who wrote us on Twitter. He said: Everyone now knows axolotls, but here in Appalachia we think bigger, offering our hellbender salamander.

And defending the hellbender in our Carnival is Lauren Diaz, PhD student in fisheries science at Oregon State University, in Corvallis, Oregon. Welcome, Lauren.

LAUREN DIAZ: Thank you. I’m so happy to be here.

IRA FLATOW: Oh, we’re happy to have both of you. I can’t wait. We’re excited to have you all here.

And just to note, this segment was recorded in front of a live Zoom audience. And if you’d like to join us live on the next time we do this, to find out how you can join a future live radio recording, go to sciencefriday.com/livestream.

OK, let’s go first with a basic description of these creatures. What do they look like? Where do they live? Jason, you’re up first. Start with the mantis shrimp.

JASON DINH: Sure. So mantis shrimp are about 450 known species of crustaceans in this group called stomatopods. They live in the tropics and subtropics, in burrows on the seafloor. And these can be either constructed burrows out of sand or they can be from natural crevices in things like corals or rocks.

And so they’re pretty small. They could be anywhere from less than an inch to over a foot. But generally they’re around the size of a cigar, or your finger. And they could be anywhere from just plain beige to just extremely gaudy and colorful.

They kind of look like lobsters in the back, but in the front they’re just totally unique. So they have these huge eyes that kind of just are always moving independently from one another. They have these antennal scales that flare out from the sides of their heads that are super colorful. And they have these really fast feeding appendages that they fold up underneath like a praying mantis, which is how they get the name mantis shrimp,

IRA FLATOW: Laura, I think you’ve got your work cut out for you with your hellbender. Give us your best description of the hellbender.

LAUREN DIAZ: Yeah, absolutely.

IRA FLATOW: It sounds like a motorcycle group to me, but tell us tell us what it is.

LAUREN DIAZ: That would be a really good name for a motorcycle group.

So hellbender salamanders, really broadly, are in the giant salamander family, Cryptobranchidae, which are the largest amphibians on Earth. And actually hellbenders are North America’s largest amphibian. So I like to describe them mostly as kind of like a big slimy rock. That’s what they look like to me. They’re really good at camouflage.

They can reach up to about two feet long, which is really, really big; have this really like flat, wrinkly, brownish, blotchy body. So when you see them underwater it’s hard to see them, especially from above the surface. They just look like another rock. These beady, tiny little eyes. A big paddle-like tail for swimming. Keratinized toes, which truly the only salamander I know that has pretty much fingernails. And they use that to crawl along the rocks and really hold their grip.

They are fully aquatic and don’t have external gills. So that’s actually where the name Cryptobranchid comes from, hidden gills. And as far as their habitats, they live under boulders in rocky clear mountain streams with fast-flowing water throughout Eastern North America. The best populations are around the southern Appalachians, like North Carolina, Tennessee. There’s other populations up north, around Pennsylvania and Ohio, that are still existent. And then there’s also a disjunct population in Missouri, which is considered a critically endangered subspecies.

And so their need for clean, fast-flowing water is, spoiler alert, a bit of a problem these days. So, yeah, I think that’s a fair description.

KATHLEEN DAVIS: Now, Katherine, one of our listeners from the Hudson River Valley, has a question about how the hellbender got its name.

LAUREN DIAZ: Yeah, that’s a question I get so often, because it is such a weird name to give an animal. But it comes from probably the fact that they are considered traditionally ugly to a lot of people. I don’t think so, but a lot of people do think that. And so, back in the day, the first time people ever saw them it was like, oh, man, this creature from hell, bent on returning. That’s like the thing that everybody says.

KATHLEEN DAVIS: Now, one other thing that I wanted to ask about hellbenders, one of my favorite things about them is that they have a lot of nicknames, so I’ve heard snot otter, devil dogs, lasagna lizards.

IRA FLATOW: Lasagna lizards!

KATHLEEN DAVIS: I know. I know.

IRA FLATOW: Wow!

KATHLEEN DAVIS: Do you have a favorite nickname, Lauren?

LAUREN DIAZ: Yeah, actually, lasagna lizards is probably my favorite. And they’re called that because they are so wrinkly. So the sides of their body look like the sides of a lasagna. Which is so creative. But, yeah, snot otter is probably the most common one. I have also heard Allegheny alligator, since they’re up in Pennsylvania/Ohio region. But yeah, real fun nicknames. People love that.

IRA FLATOW: Wow, that’s terrific. Yeah, I love something with a lot of names.

I’d like to go back to something Jason said about the mantis shrimp: the color can be really incredible. As our listener said, they really do seem decked out for a carnival. What role does color play for all of these creatures?

JASON DINH: Mantis shrimp vision is kind of incredible on a couple of fronts. And they have a totally unique way of seeing color, which is what’s so cool about them. Mantis shrimp have 12 types of color receptors. We have three: red, green, and blue. Your dog has two. Birds have four. They have one that can see into the ultraviolet. And mantis shrimp can also see into the ultraviolet, but there’s this kind of crazy question of, if birds can do it with four, why do mantis shrimp have 12?

And so one theory that people had was that, well, maybe if they have 12 color receptors, they can better discriminate between colors. But experimental evidence in the last 10 years has shown that they’re actually not that great at discriminating between colors. They’re about five times worse than people are.

So to this day, it’s still not really clear why they have 12 cones. And there’s a lot of ongoing work trying to figure this out. But the prevailing theory so far is that it’s a way for them to really quickly identify colors. So when we identify a color, we have to basically, in our central nervous system, compare the stimulation of all three types of our cones to figure out what color that is. But if a mantis shrimp, for example, just has a yellow cone, it can just have a very quick lookup table and say, that’s yellow, without having to do any cross-cone comparisons.

IRA FLATOW: Wow. Great description. People may have heard about these before because they’re famous for their punches. Tell us a little bit about what the heck is going on with their amazing punching power.

JASON DINH: Sure. Mantis shrimp achieve one of biology’s just highest acceleration movements. They can exceed what humans can engineer, both in terms of size and speed. And so they’re remarkable on a couple of fronts. They are really brief. So an individual strike lasts about 3 milliseconds. I would say that’s like in a blink of an eye, but that would be a total understatement. A blink of an eye takes about 100 times longer than that. Their peak speeds reach that of a car on the highway, around 70 miles per hour. And they’re accelerating probably around equally to a bullet coming out of a .22 caliber rifle.

When they actually strike something, their peak forces are equal to that of a hyena, which are these animals that have specialized skull structures to literally crush bone. And they’re doing it at such a different size. So mantis shrimp feeding appendages are less than a gram. They’re about the mass of two toothpicks. Hyenas are about 20 kilograms. So that’s a 20,000-fold difference in mass and producing the same peak forces.

They’re doing it by using a series of springs and latches. So instead of actuating their movements with muscles, they’re actually actuating it with springs. And so this is similar to using a bow and arrow. If you wanted to throw an arrow using just your muscle power, you, or at least I, wouldn’t be able to throw it very far or very fast. But if you kind of just took that same energy, loaded it into a springy bow, latched it until you wanted to release it, and then let go, you could get the arrow to go really far and really fast. And so that’s basically what mantis shrimp are doing.

They have these really high-force muscles inside their feeding appendage that they use to slowly load all of these spring-like elements inside their feeding appendage, things deforming their cuticle. And they hold it in place with a latch until they’re ready to strike. And as soon as they let that latch go, a huge amount of power delivery goes to this rotating hammer that they use to smash their targets.

And they do it for a couple of things. They use it to smash prey. They can break open snail shells. They actually hit the shells so hard that they’re boiling a tiny layer of water on top of the shell. It’s a phenomenon called cavitation. They’re literally ripping the water molecules apart into water vapor. And when that bubble collapses, it’s super energetic. It creates super loud sounds, tiny flashes of light and heat, equivalent to that of the sun. And the force of that collapse can actually exceed the force of the initial strike of the hammer. So with one strike, they get two punches to break open these shells.

And they’re super clever with how they actually use the strikes. So they’ll target this snail right at the opening, where they’re most likely to break it open and get the meat. If the snail is too tall, they’ll do this kind of like rotation thing, and they’ll hit them at the top, where they’re most likely to get fractured. So they’re hitting hard and they’re hitting really cleverly.

IRA FLATOW: Just a quick note that I’m Ira Flatow, and this is Science Friday, from WNYC Studios.

Wow. So much good stuff. So much to digest about these two Charismatic Creature candidates.

It’s time to hear your final arguments, your best and final arguments, for why your creature is the most charismatic.

Jason, let’s start with you.

JASON DINH: Sure. I think that mantis shrimp are the most charismatic for two reasons. One is that they’re totally unique. And that’s due to their evolutionary history. And two is that they’re totally awe-inspiring animals. There are a lot of animals that do one or two really cool things. But it seems like wherever you look, the mantis shrimp is doing something kind of remarkable. Whether it’s like a totally unique way of seeing or devastatingly fast strikes. And so in this way it’s kind of like a glimpse into nature’s evolutionary playground, where we can find some really unique solutions to evolutionary problems.

And as scientists and engineers, the more we learn about what mantis shrimp do, it seems the more we’re learning how to apply these to our own science and engineering. So there are some engineering groups working with the lab that I’m in to look at how the individual components of a mantis shrimp’s feeding appendage can inform really small and fast robots.

There are material scientists looking at how mantis shrimp can break open snail shells but not damage their own hammer in the process, to make impact-resistant materials. If you remember cavitation, it happens everywhere when you move really fast. Ship propellers cavitate all the time, and it destroys ship propellers. It can blow the cover of submarines. But mantis shrimp, despite being able to cause cavitation on these snail shells, almost never cavitate on themselves, even though they’re moving incredibly fast.

So there’s just so much behavior and morphology that we’re learning about the mantis shrimp, and I think we’re just starting to scratch the surface.

KATHLEEN DAVIS: OK, Lauren, it’s your turn. Very different creatures, but they’re exciting in their own ways. Let’s hear your argument in favor of the hellbender.

LAUREN DIAZ: Yeah. If the name snot otter didn’t already convince everyone that they’re the most Charismatic Creature. I would say that they’re also incredibly unique, pretty much a living fossil, a relic of the past. There’s only three giant salamanders on Earth, and we are lucky enough to have one of them. And they also, to me, personally, represent this amazing and fragile and sensitive and beautiful habitat. There’s nothing more beautiful than being underwater in a clear mountain stream and seeing all these super cool fish and insects that nobody ever really gets to see. And to me hellbenders are kind of the poster child for that environment and are a big reason why I love them.

And they can act as an umbrella species. When you protect hellbenders, you are basically protecting everything else in the stream. So in that way, they’re like the poster child for stream biodiversity and conservation to me.

KATHLEEN DAVIS: Two great arguments. And Ira, this is normally the time where I’ll ask you to choose whether you think these creatures are charismatic or not. But because this is the Charismatic Creature Carnival we already know that these are very charismatic creatures and we’re going to do things a little bit differently.

IRA FLATOW: Glad you’re taking the pressure off of me. All right. So what are we doing this week?

KATHLEEN DAVIS: So this decision is now in the hands of our listeners. We want you to vote for which of these creatures is your favorite that we talked about today. Which one do you think is the most charismatic? We want to hear from you.

So to vote throughout our Carnival, not just today, you’re going to go to sciencefriday.com/carnival. Voting is now open for this first match-up, until next Wednesday, at 10:00 AM Eastern Time.

IRA FLATOW: Let me repeat that important link. It’s sciencefriday.com/carnival.

And I am on the edge of my seat, to see what you listeners choose. Because this is exciting.

I want to thank our experts this week. It was great to learn more about these charismatic creatures. Jason Dinh, PhD candidate in biology, Duke University, in Durham, North Carolina. Lauren Diaz, PhD student in fisheries science, Oregon State University, in Corvallis. Thank you both for joining us.

JASON DINH: Thanks for having me. Vote mantis shrimp.

LAUREN DIAZ: Yeah. Go hellbenders. Thank you so much.

IRA FLATOW: OK, Kathleen. Who or what is in store for our Charismatic Creature Carnival next week?

KATHLEEN DAVIS: So next week we are going mammalian. It’s a head-to-head match between the opossum and the aye-aye.

IRA FLATOW: Yes, captain– oh, the creature, the aye-aye. I see what you’re saying. These are some funky creatures.

KATHLEEN DAVIS: Yes. And so our listeners can join the behind-the-scenes recording of that segment and get the opportunity to ask our experts questions. That’s happening next Wednesday, at 4:00 PM Eastern Time. Go to sciencefriday.com/livestream to sign up.

IRA FLATOW: Thank you, Kathleen. Terrific job today.

KATHLEEN DAVIS: Thanks, Ira. Excited to keep the Carnival going.

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