SciShow Tangents - Stomachs

Episode Date: November 12, 2024

From one to four to none at all, stomachs enjoy a stunning variety across all the creatures who have (or don't have) them. And with our stomachs all happily full of spooky month treats, we thought it was the perfect time to learn all about this weird, wobbly, wonderful organ.SciShow Tangents is on YouTube! Go to www.youtube.com/scishowtangents to check out this episode with the added bonus of seeing our faces! Head to www.patreon.com/SciShowTangents to find out how you can help support SciShow Tangents, and see all the cool perks you’ll get in return, like bonus episodes and a monthly newsletter! A big thank you to Patreon subscriber Garth Riley for helping to make the show possible!And go to https://store.dftba.com/collections/scishow-tangents to buy some great Tangents merch!Follow us on Twitter @SciShowTangents, where we’ll tweet out topics for upcoming episodes and you can ask the science couch questions! While you're at it, check out the Tangents crew on Twitter: Ceri: @ceriley Sam: @im_sam_schultz Hank: @hankgreen[This, That, or the Other: Stomachs ROCK]Bird with over 1% of their total body weight of gastrolithsAquatic animal helps control buoyancy by swallowing silt Animal eats its exoskeleton that stores calcium in stomachhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC8342792/#bib0037https://www.researchgate.net/publication/6549149_No_gastric_mill_in_sauropod_dinosaurs_New_evidence_from_analysis_of_gastrolith_mass_and_function_in_ostricheshttps://bonndoc.ulb.uni-bonn.de/xmlui/handle/20.500.11811/2110https://www.jstor.org/stable/4098635https://pubmed.ncbi.nlm.nih.gov/26818557/[Trivia Question]Mammal species without stomachshttps://www.livescience.com/41661-why-platypus-wont-regain-stomach.htmlhttps://royalsocietypublishing.org/doi/10.1098/rspb.2013.2669https://www.nationalgeographic.com/science/article/how-the-platypus-and-a-quarter-of-fishes-lost-their-stomachshttps://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/monotremes.htmlhttps://m.youtube.com/watch?v=A5Rzx7yeh7c[Fact Off]Ghost crabs use their stomach teeth (gastric mills) to growlhttps://royalsocietypublishing.org/doi/10.1098/rspb.2019.1161https://www.science.org/content/article/listen-ghost-crab-frighten-away-enemies-its-stomach-rumbleshttps://www.theguardian.com/science/2019/sep/11/ghost-crabs-use-teeth-in-stomachs-to-growl-at-predatorsSomeone ate a shrew to study what human digestion does to rodent bones [Ask the Science Couch]Borborygmus and the biology of stomach rumbles  https://www.scientificamerican.com/article/why-does-your-stomach-gro/https://www.etymonline.com/word/borborygmushttps://www.nature.com/articles/nrgastro.2012.57https://journals.physiology.org/doi/full/10.1152/ajpgi.00212.2015Patreon bonus: Stomach and brain communication for hunger/satiety (or other things) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3174087/https://www.ncbi.nlm.nih.gov/books/NBK555906/https://journals.physiology.org/doi/full/10.1152/ajpgi.00448.2003https://www.livescience.com/health/food-diet/does-it-really-take-20-minutes-to-realize-youre-fullhttps://www.journals.uchicago.edu/doi/full/10.1086/693111[Butt One More Thing]Florida carpenter ants swallow their own formic acid to help protect their stomachshttps://elifesciences.org/articles/60287https://www.eurekalert.org/news-releases/491275

You're listening to a Complexly Podcast. Hello and welcome to SciShow Tangents. It's the Lately Competitive Science Knowledge Showcase. I'm your host, Hank Green, normal Hank Green, not spooky. And joining me this week, as always, is normal, not spooky, Sarie Riley. Hello. I'm so normal. And also our resident every wolf man, Sam Schultz, who's still a wolf. Oh, I get to be scary still in November.

I like that. Yeah. OK. Oh, still. to be scary still in November. I like this. Yeah. Okay. Oh, still. All right, everybody. What was your favorite Snick Snack patty whack in your mouth for Halloween? Oh, always a Reese's pumpkin. Always. Always a Reese's pumpkin.

Always a Reese's pumpkin. You know, I have to fight you. And I think that the chocolate to peanut butter ratio is better than the original peanut butter cups. I totally agree. I ate a Reese's pumpkin this year and I must be growing up because I was like, this isn't all it's cracked up to be anymore. They're so soft.

There's a little bit of texture variation with the peanut butter cup where you get the hard outer layer. The rim is a little firm. And then Reese's pumpkin is just like squish all the way around. That's what I want. Squish in the mouth. Soft, pliable. Yeah. Peanut butter goo.

You make it into, just make it into a ball in there with your tongue. No teeth required. That's what the young people say. I want a treat with no teeth required. No teeth required. Actually, this is true. I have a fact.

Do you want to hear it? Sure. I would love to. Are you surveying children? No. What's the deal here? So, in the last 10,000 years ago, humans' teeth have gotten way more crooked. And it seems like this is because of a lifestyle change, where we went from eating really hard

stuff all the time, and to get any nutrition at all into our little kids, we had to have them chewing on seeds. And then once we got like good agriculture, we had like mac and cheese and stuff, and then our jaws actually do not grow as much because they are not as stressed as we grow up. And so there's not enough space for the normal amount of teeth that would fit into a properly stressed jaw.

So we do like it soft, and it is actually causing a problem that we solve with orthodontics. The dentist did say, my mouth is too small. My dad's mouth big enough for wisdom teeth. He didn't have any of them pulled. I had all of mine pulled because they were like, Was he like a bone chewer?

I guess so. Maybe he grew up outside where the Hanford nuclear power plant was. And so he did all kinds of random things. Probably chewed on sticks by the river. They radiated river sticks. But now I got soft Reese's pumpkin small mouth. They had to pull out teeth to not mess up my other teeth.

If you had been eating regular Reese's, you wouldn't be in this jam. I guess so. Yeah. Did you get your wisdom teeth pulled? I did. Yeah. I got three of mine done. What happened to the fourth? I got one lone friend who's like, I guess I'll just stay around back here. So you have one extra tooth in the back of one side of your head Yeah, so they went in to take it out They even like did the incision and then they were like, yeah, I can't get it

They gave up they got all kinds of drills and stuff in there I don't know that I think they got in there like actually that one looks fine I think we should just leave it. It's gonna be so hard to take out and he's not doing anything bad. This is the most beautiful tooth we've ever seen before. So every time I go to the dentist, they do my x-rays and they're like, why do you have one wisdom tooth? You're like, I just enough seeds to get that wisdom tooth and to keep it around. So I chewed on his one quarter as many rocks as I needed to in order to keep it. What's your favorite tricky treat?

My favorite tricky treat? I'm I'm like between candy that I like right now. I went through a big period where they were making a lot of fun Twix flavors that I was really enjoying. I like a salted caramel Twix, but I did have something great. They were sour punch straws that were like the, you know how there's like those birdie bots, every flavor beans and some of them taste like diarrhea and some of them taste like chocolate. You don't know what's what I found those, but they were sour punch straws and they were all green except some of them.

And so it was like green apple, whatever other green flavors there are, except like one in every 10 was pickle flavored, but the pickle ones were also really delicious. It was supposed to be a punishment, but instead it was a great, yummy, yummy pickle. Like a sour pickle. So this sour pickle, sour punch. Maybe that's the next big thing, Sam's Sour Pickles, but there is a, it's a sweet treat.

Sam's Sweet Pickle Treats. Okay, I'm in. I got nothing else going on. Yeah. You got to diversify. What's your, what kind of candy you like? Oh, it's, I mean, it's not really a stinky snack tricky treat. Okay. I'm in. Same sweet pickles. I got nothing else going on. Yeah. You got to diversify. What kind of candy you like? Oh, it's, I mean, it's not really a stinky snack tricky treat.

It's your cover of my patties, but you get them sometimes. That's a stinky snack tricky treat. Yeah. That's the best one. It's the best of all the things. I really come around. They are really freaking good. I like a little sharpness to my sweet and the mint is nice.

Mint is, yeah, you can't go wrong with a mint candy. I feel like I love mint candy so much. Yeah. Mint, what's the red one? What's red mint called? Cinnamon. Oh, peppermint? Cinnamon.

Oh, cinnamon. It's like hot spicy, not cold spicy. Every week here on SciShow Tangents, we get together to try to light up a maze and delight each other with science facts while also trying to stay on topic. Our panelists are playing for glory, but also for Hank bucks, which I'll award as we play. And at the end of the episode, one of these two people will be the winner. But first, as always, we must introduce this week's topic with a traditional science poem. This week, it's from Ceri.

You and me are animals who eat up lots of food, but it's hard to extract energy when you are just a tube. So we evolve some chambers in one of which we chew, another extrudes acid, and others absorb what's spewed. That which secretes and turns and stores goes by many names, gut and tummy and belly and stomach all work just the same. Some animals have one or two or ten or none to claim, but no matter what they've got inside, it's not

a source of shame. So whatever you might call it and whatever it might do, know your stomach is somewhere between your mouth and your poop. So, the topic this week is stomachs, but before we dive in, we're going to take a short break, and we'll be back what a stomach is. When it comes to everything else, it gets really messy really fast. Is that right? What about all mammals? I bet all mammals we got to work with.

No. You know, we're not working with the same hardware in there. Think of a cow. They got a bunch of stomachs. I'd love to think of a cow. I'm thinking of one right now. But just because they have a bunch of them doesn't mean that that's not. Are those stomach?

Are they all the same things what we got? They got chambers and the anti-chamber or do they have like a stomach? And then they have like another thing. Because one of the things one of my facts that people love is that the pelicans have three stomachs and one is just for bones. But I think what people imagine is that like the bones go off to the right and the flesh goes off to the right and the flesh goes off to the left, but they're all in sequence and the bone stomach is just like gets all the bones

collected in it for slow dissolving. It's not, it's wild pelicans. Just- They melt the bones? They got to melt, they eat the whole fish. They melt the bones. I guess so. They melt them or poop them and you don't see little bones in the bird splat. Am I right though, Zari? Are we, are we, do we get confused about stomachs? Melt the bones. You either melt them or poop them and you don't see little bones in the bird splat. Am I right though, Zari? Are we, are we, do we get confused about stomachs?

Yeah, I mean, the more that I looked into it, the more that I feel like we just call whatever main digestive chamber is in an animal or an insect or something. We just like, that's a stomach. But sometimes they also have other names besides stomach. Well, I have a complaint, which is that I think my main digestive chamber might not be my stomach. What? Why isn't it my small intestine? It's bigger. I don't know. I think the one that stores the one that stores, I guess, intestine absorbs, I guess it kind of stores, but it's always moving through. Yeah.

Squishing, squashing, moving through. Stomach can build up for a little bit before the sphincter extrudes it. Yeah. Elsewhere. Gross. But yeah, in humans, it's pretty clear. It's always a little bit higher than you think it is. I feel like people pat their tummies and that's all intestine in there. All intestines.

All intestine by your belly button. Stomach's like up in the ribs. Right below your heart, kind of. Yeah, it's wild because you think that it's like lungs and then viscera. But in fact, they overlap like your liver is up there over your lungs. Yeah. So like stomach is like right below your heart and livers on the other side. Right. Yeah. In rib cage area. Well, they work in. They're doing something together, aren't they?

Are they friends? Well, they're all in that they're keeping your body alive together? Yes, and they're all kind of squishy, but they do very different things. Yes, and they're not connected together. I mean, by the blood, I guess they are. So when you get like a, I guess when you get like a bad stomach ache,

you're actually getting a bad lower intestines ache? I, a person who gets tummy aches, can confirm that you feel, like when your stomach hurts, you don't feel it where your stomach is. This is one thing I would fix about human bodies if I could, is that the nervous innervation of the belly is just not specific.

So if there's like pain in there, this is why like if you get your nuts hit, it feels bad in your belly. It's not, nothing's making sense. The pain is never specific to the right area. So you kind of can't go on pain when you're trying to figure out exactly what's hurting. Though some like appendix pain is actually pretty specific.

But a lot of times just sort of like a bland belly ache is a stomach problem, but you don't feel it right where your stomach is. That's so weird. It's a bummer for abdominal pain sufferers because you never know what the problem actually is. There's too much stuff. There's too many organs squishing around in there.

You can't localize what's wrong until, and then you have to go to the doctor and be like, tummy hurts. Yeah, and then like, all right, well, we'll put it in both ends. Oh no, that's what they do to figure it out. They will. Yeah, sometimes they'll they'll do an endoscopy and a colonoscopy. At the same time.

Not at the same time. At the same time, they meet in the middle and say, good. Lady and the Tramp style, the two scopes give a little smooch. None of that's the tale. Is that how Lady and the Tramp worked? I don't know. I've never seen it. I think it's the same thing though.

But this is like two noodles. Yeah, it's two noodles. It's truly an opposite Lady and the Tramp situation. Yeah, opposite Lady and the Tramp. And it happens right in the duodenum. Yeah, I miss it later in the tramp. And it happens right in the duodenum. Yeah. So anything else?

What do we know? Anything else? Oh, so I can give you some of the names. So in insects or in invertebrates, usually what we call the stomach colloquially is a crop where it stores food, but it doesn't necessarily secrete digestive juices or enzymes in the same way as our like some of them do some of them Don't some of them have to get stomach the acids from their environment. Yeah, okay So that's the thing is juice doesn't need to be juicy to be a stomach Yeah, okay, then some things that are called stomachs or maybe not stomachs. Well, but that's a crop. It's got its own name

It's a crop. Yeah Birds there are two stomachs. One of them is the proventriculus, which is where gastric juices are produced. And then the second stomach in some birds are the gizzard, which is where it's kind of soaked, it ferments a little bit, it gets mechanically ground up. And sometimes birds put like stones in their gizzard. Also, it's more muscular. And then when you get into ruminants and pseudo ruminants, that's when you start getting lots of different chambers. And I think we say that cows have four stomachs or camels have three stomachs, but really they're different

stomach chambers. And usually the last one of them called a, oh, I didn't look up how to pronounce this, abomasum, abomasum, is the last one. And that's where a lot of the gastric juices are secreted. But then the first three stomachs, for example, in like a cow or sheep or deer, those are where the microbes exist in the rumen that break down the cellulose where they eat it, puke it up, chew a little bit more, eat it, ferment a little, puke it up. But there aren't gastric juices going on there. They're just like extra chambers along the way.

And they need all that because it's so hard to eat the grass. Is that why? Because this is so hard to make anything out of it. I think so. Yeah. So hard to make the grass. They want to filter out stuff, like filter out dirt or sand. They're not chewing on that as much. So they have all those multiple chambers help with that, I think. Seems like there's too much cow to get it all inside of one cow.

You know, the thing about our organs is that they squish around so much. I don't know if you've ever looked up a diagram of a pregnant person and how the baby just like shoves the organs to the side. Oh. Cause they can just squish them aside. They're so squishy. So I imagine.

Sometimes a cow's got all the cow organs in there, but then also a cow as well. Also a cow. And so you just squish the stomach chambers aside or sometimes the rumen's really big and full of grass and sometimes hasn't eaten a lot of grass, so. And then like you think, because you see the diagrams, that it's all kind of like nice in there,

but in fact it is a bit of a mess. And sometimes they're in there and they're like, where's his gallbladder? And they're like, I don't know, somewhere it's got, let's keep looking. Yeah, you gotta imagine that, as you're moving around, your innards are sloshing around. Yeah, I don't actually have to imagine.

I try not to. Sometimes I'll feel a little pop when I like twist. And I'll be like, I don't want to know what that was. It's just something swinging in its little hammock. Something's slanging in its little hammock. And do we know where the word stomach comes from? That sounds like an old one. It is an old one. And it has been where the word stomach comes from? That sounds like an old one. It is an old one. And it has been basically the same word. So it comes from the French

estomac. I don't know how you say it. Beautiful. From the Latin. The language of love. Yeah. And then the Latin and Greek stomachos or stomachus. And what's interesting- From stoma? Is it from stoma?

Yeah. It's from stoma, which means an orifice or a small opening. And what's interesting is that in Greek and Latin, it did not mean like belly necessarily. It started out to mean like your mouth or mouthpiece or any sort of orifice. It was everything was the stomach or esophagus. Oh, that's a stomach. Your mouth. Oh, that's your stomach. Show that in your stomach.

What the heck? That's just a stoma. Like, have you heard the word stoma? Like stoma, same hole of like on the bottom sides of leafs. Stomata. Same same root word. And there was in the 1500s, there was a wave from certain anatomists, I think Galen area, who attempted to restore the word stomach to its original Greek sense.

And they were like, let's call the esophagus, let's call the mouth stomach again, bring back stomach and let's call the stomach the ventricle. And I'm really glad that they didn't win because that's the wrong word for it. I would not say I eat too many hamburgers and my ventricle hurts. Yeah, my venti. Oh, my little venti. I think that would work. I like that.

And that means it's time to move on to the quiz person of our show. In today's episode, we're talking about how stomachs rock. And in today's game, we're going to talk about stomach rocks, gastrolytes, or any mineral that is found in the digestive tract of an animal. Best known for helping birds digest food, gastrolytes are also found in dinosaurs, extinct marine reptiles and many animals around today. So we're going to talk about a few different uses for stomach rocks. And you're going to guess

the stomach rock-having animal. Are you ready? Yes. Yeah. Okay, number one, digestion is the best understood function of gastrolytes. Birds don't have teeth, so they've picked up the habit of swallowing rocks to help grind up food in their stomachs, or technically their gizzards.

Or crops? I'm confused. But there's one kind of bird that's notable for having, like, a lot of gastrolytes, over 1% of their total body weight. Is that the common ostrich, the emperor penguin, or the great horned owl? Oh, I would have, I was feeling like it was a turkey for some reason. That is not your options. Because you cut into a turkey and at Thanksgiving and all those rocks pour out every time.

And you're like, dang, that's a lot of rocks. Don't forget to put the rocks in the broth. Yeah. Make a wish on the rock. The ostrich of those. Well, penguins don't fly either. But I feel like penguins got to swim. Ostrich is safe on land. If they had a lot of rocks in them, they don't have a risk of sinking or falling because

of it. Ate too many rocks. Ate too many rocks. Yeah. So I think it's an ostrich. And then that horned owl, they got to fly quiet. The rocks would be in there rattling around. Clacking around.

Clacking around. Yeah, alerting every mouse in that vicinity. I think an ostrich too, those guys look like they eat rocks. Look at them. Look at them. They look like they're 1% rock. So yeah, ostriches are big and you would not be wrong that they need some good old big rocks and it's not so bad to have a bunch of them inside of them.

But the need for a lot of stomach rocks is actually because they are herbivorous and they need to grind up all that tough plant matter compared with birds that are more meat based and Other herbivore birds can also approach 1% of their weight in rocks, but because ostriches are so big That's a lot of rocks. It's like a whole kilogram of rocks fun If you ask penguin because that would help them control the buoyancy ostriches are so big, that's a lot of rocks. It's like a whole kilogram of rocks. Fun. If you ask penguin, because that would help them control the buoyancy, how about we do number two? Because this is a separate one. It is often proposed, though rarely proven, that an aquatic animal can help control its buoyancy and water by swallowing some rocks.

However, researchers were able to demonstrate in one tiny little guy by swallowing some rocks. However, researchers were able to demonstrate, in one tiny little guy, that swallowing silt led to an ability to change their specific gravity in water. Are these little guys zebrafish, tree frog tadpoles, or sea cucumbers? I don't think sea cucumbers care enough about their buoyancy. Yeah, they're sort of sinkers. I guess they're sinkers. They just are where they are. I guess they're sinkers. They just are where they are.

I'm just here. It's good to sink if you need to sink. It's good to stay on the bottom if you need to be on the bottom. That's true, that's true. I feel like this is always a trap. I feel like I would've read about it if it was a zebrafish. Well, now that's the problem I'm having

because I'm so positive that I did a fact about zebrafish years at this point ago. And like, I'm tricking myself into thinking that it was something about rocks, but I think it was like something cute that they did with rocks. Like, like they, they had a little house or something that they would build. So I, and I, I think as a tree frog tadpole, I could see using its little mouth, put a rock in there, then later, peek it out, go back up.

But I'm going to kick myself if I don't go with zebrafish. So I'm going to go with that one, I think. Yeah, I'm going to go with tadpole if only because that feels something about them being growing up in an amphibious way. Like your puddle gets bigger, you got to eat more dirt. Your puddle gets smaller, you got to eat less. Your puddle gets smaller, you gotta eat less dirt. Something like that. You gotta adjust more.

They gotta have some tricks to make it through. The answer is, well, let me see if you can guess. The paper was titled, Larval Anurins Adjust Buoyancy in Response to Substrate Ingestion. Does that help? Sounds frog-like, huh? That's a frog. Yeah. A neuras frog, frog-like, huh? Yeah. A nervous frog, right?

That's, yep. That's very, do you, you know, I don't think I could have told you that. But. I guess they had to say anurans because tadpole didn't sound cool enough. Yeah. Or larval anurans.

Just say tadpoles, you guys. But anyway, researchers gave tadpoles access to silt and showed that swallowing it led to better swimming. In almost every other aquatic animal with stomach rocks, their function in buoyancy is wildly controversial. You do not need to know how deep of a rabbit hole that was gone down concerning specifically sea lions and whether they have rocks that they eat. But man, we'll figure it out someday. But I'm not I'm not joining aside yet.

I feel like a sea lion would have to eat so many rocks to make any kind of difference. But yeah, just get little ones, a bunch of little ones and ostrich amount of rocks to do anything. Maybe they just eat ostriches and they get the rocks accidentally. This is a problem with aliens that want to eat whole humans is that we are constantly covered in synthetic fibers and glasses and like a metal hips and stuff. So that's why they stopped doing it. We talk about the microplastics but the aliens really had to deal with the macroplastics and that

was a whole can of worms. It was bad enough that we got all these bones and teeth. The giant human-eating aliens they just gave up. They like, they tried like four of us and they left. There's better rhesus pumpkins out there in the universe. No. Much softer. All right, number three. There's one category of animal that rather than swallowing stomach rocks

makes their own stomach rocks. The reason they do this is because they shed their exoskeleton and they wanna hang on to some of the minerals to use again later. I love that. Which animal stores calcium in its stomach to help build a new exoskeleton? Spiders, crabs and crayfish, or cicadas?

Cicada don't care. They are truly just floating through life, I feel like. They have such a limited amount of time, I think, don't they? They got work to do. They ain't eating nothing. Yeah, they both have a lot and a little time. Yeah, that's true. But a lot of their time is just being boring underground.

Yeah. And when they're out, we gotta go. Crabs and crawfish, I would say that their stuff drifts away too fast, and they're like, oh no. They just, they molt their exoskeleton, they're like, well, damn, that's going away. Yeah. Spiders, spiders can do anything.

I believe a spider could achieve anything it wanted. And we could do this. I'm getting hung up on the cali- I feel like maybe I just don't know what exoskeletons are made of because I'm imagining any of these with calcium in them going, which one's bony? I don't know what exoskeletons are made of because I'm imagining any of these with calcium in them going, which one's bony? I don't know. Yeah. Well, it's, yeah, that is a, that actually might lead you in the correct direction. Makes sense.

Yeah. We've got crabs and crayfish, which are chitin, I think. They're also, I think they're all chitin. I think they're all chitin. They're all chitin. But chitin isn't all the same. But chitin isn't all the same. But chitin isn't all the same and I don't know enough about that chemistry. I never heard of a crawfish giving you calcium but.

Yeah. Imagine eating. If I ate a spider would I say mm-mm-mm. That's like a one serving of milk. That's boned. Yeah. If I eat any one of these would I go, tastes like bone. I'm gonna stick with spider. Tuna very presumptuously put that I guessed spider, which I did not officially do. Oh, okay. But you're sticking with it now. I'm sticking with it.

I trust my boy. Yeah, I guess I'll do. Crabs and crayfish are different than the other two. They're not an insect, they're a crustacean. So maybe there's some bone. Why is it two? The fact that there's two seems like an over-the-top thing. That does seem like it's probably the right answer. I don't know why. It could be just one or the other. It would still be true. But,

Sarah, you are correct. The chitin can mix with calcium carbonate to make a stronger, thicker The chitin can mix with calcium carbonate to make a stronger, thicker chitin. And that is what is going on in these marine arthropods. Supposing they don't end up in a crawfish boil, crawfish and other similar arthropods like to plan ahead for their next molt. And these deposits seem to be mainly calcium, but researchers have also found elements like iron, magnesium, and phosphorus, and something else. But my Google Docs just signed me out and there's a big window. Crawfish have the same problem that humans and giant aliens do. It's hard to undress a crawfish and eat it. But we're tenacious. Those aliens are ours.

Yeah, we really figure out how to eat crawfish though. Nothing's stopping us. Even though it's maybe a lot of work to get each individual little slice of meat out of there, we do it. Whenever I'm eating, like if there's actually crawfish in a dish, I'm like somebody worked so hard. A lot of prep for that one because usually they just bring you out like the crab and say you take care of this. You figure that out.

We're done. I've brought you a tool or seven tools. Well, let's see if I can get my Google Docs to work again. We're going to keep on going. Ah, I see. Right now, we've got Sam at one and Sari with three. Next up, we're going to take a short break and then it will be time for the Fact Off. off. Welcome back, everybody.

Get ready for the fact off. Our panelists have brought in science facts to present in an attempt to blow my mind, and after they've presented their facts, I will judge them in a word Hank Bucks anyway I see fit, but decide who goes first. I have a trivia question. Here it is. There's plenty of hullabaloo about mammals that have multiple stomachs like cows and camels, but what about the mammals who can't stomach, well, stomachs? That's right, there are mammals who have no stomach at all, but just how many are there?

That's up to you to guess. How many mammal species don't have a stomach? Closest guess wins. Oh, I know seahorses don't have stomachs, but they're not a mammal, they're a fish. They're not a mammal, Sarie. It's not a mammal. Okay.

Ah, ah! I know it's called horse, but it's not a mammal. I just processed it. Monotremes don't. So echidna platypus. Is that something you know? Is that a fact you know that they don't have stomachs? I know that from SciShow Kids, Hank.

So ketchup. Wow. I didn't know that. Yes, because they're just weird. They're weird. Maybe, I don't know why they're tubes instead. But, so maybe like two? Two, I'm gonna guess two.

That was exactly what I was gonna guess for the same reason. So I don't even know what to do now. I'll guess 10,000. No! No! No! No! No!

No! No! Well, I have the number showing up right in front of me. It's actually 9,999. Yes, I have the number showing up right in front of me. It's actually nine thousand nine hundred and ninety nine. Yes, I'm so smart. Actually, the answer. Oh, my God, Sam, it's five. The answer is five.

You could have just said, I could have said three, but I really thought it was two. All in on two, all or nothing on two. So duck build platypus doesn't have a stomach. All in on two, all or nothing on two. So duck-billed platypus doesn't have a stomach. So that you had that one. Yep. But actually their whole taxonomic order, the monotremes, as y'all said, doesn't have stomachs. So alongside that includes the four known species

of echidna. Oh, okay. Sonic did not teach me about that. Knuckles is one echidna, there's one guy, that's it. No, four species. He's the last of his kind, in fact. The last of his kind, one species. How are we supposed to know that?

I thought Sonic was from space. Hank, that's the movie canon, but. Sonic was born under a shrub in South Dakota or North Dakota or something like that and abandoned by his dad Well, that's another that's another interpretation of the war, sir. Okay Things like their facts No, no, why is there he's just kind of there well according to a 2014 study

The monoshoems don't even have the genes for a typical mammalian digestive system. There's quote, a complete loss of the genes responsible for pepsin and acid digestion. So instead, the esophagus fleets directly into the intestines, and they think that much of the initial work of breaking down food happens in their mouths, getting it sufficiently digestible for the intestines to finish the job without the needed help of a stomach. So they're just chewers. So why do we got them?

What are we doing with our stomach? Why don't we need to eat rocks and stuff like that? I think it just expands the number of foods you can make food out of, you know? Yeah, the amount of nutrients you can extract from what you eat, the more that you break it down, the more of that you can absorb and reuse. All right.

The next part of the show is, what do we do this time? It's been a while. It's been a whole month since we've done this. Sorry, I go first. (*both laugh*) So despite their spooky name, Ghost Crabs are pretty regular guys. They live on the shore in the intertidal zone, partway in sand, partway in water, hanging out. The ghost name is because they're usually pale and blend in with the sand and they're often nocturnal. And like

many crabs, they run and hide away from predators or start waving their claws around to scare away competitors like their other crabs, even rubbing their claws together to make a warning noise, more formally known as stridulation. So the same kind of rubbing. Anytime an animal makes rubbing sounds, like a cricket or other things. Cicadas do this, right? Cicadas do this, call it stridulation.

And in a 2019 study, researchers found that these ghost crabs also try and act tough by growling with their stomach, which has never been seen before in animals. So the team of researchers had ghost crabs, they put them in tanks and then they made them mad by poking them with a rod, wiggling around dead or alive ghost crabs or toy crabs in front of them or using one of those hex bug toy robots that kind of like- Nice. Just kind of vibrate around.

Vibrate, scare them. Uh-huh. Yeah, and they were able to provoke both male and female ghost crabs to make aggressive rasping sounds in 35 trials and even lunge and attack at whatever they were messing them with them in 77% of those situations. And while they were harassing the crabs, they used a laser beam to sense vibrations on their body as along with x-ray

images to figure out where that rasping, where that growling was coming from. And all signs pointed to their tummies. Not their stomachs though, their tummies, right? Their tum, so it is their stomach. I don't know what we call it formally, but many crustaceans have a structure in their stomach region, what we would call colloquially their stomach, called a gastric mill.

And that helps mechanically grind up food in their guts. So they're basically like bony or chitinous plates or stomach teeth. They don't have teeth in their mouths. They have teeth in their stomachs instead. They've got stomach teeth. And they rub their lateral teeth, which are sort of comb shaped against the medial tooth

to show that they were really scary and ready to fight. So they're like grinding their stomach teeth at textbooks. Gnashing their stomach teeth to seem scary. And it seems like they switch from like waving their claws and rattling their claws against each other, like stridulating their claws, to their stomach growl when they want to free up their pinchers for fighting.

So like they want to be able to talk smack and give them a little punch, like brandish their fists. Yeah, that's why I switched to fists when I start fighting instead of just biting people. Yeah, you got free up to make the sounds. And it's possible that other animals use, use like tummy growls too, but we just haven't realized it. So there's more research to be done always,

but these crabs, they're growling with their stomach teeth. Do they do this to each other or does each other know, I know what you're doing. You're not really, like, growling with their stomach teeth. Do they do this to each other or does each other know, I know what you're doing, you're not really, like this isn't scary to me, you're just- I don't know if we've observed crabs in the wild, because I guess they held an alive ghost crab near another ghost crab, but it's different

when you have an enemy in tongs or something being brandished at you. Yeah, I think so, yeah. Then like two guys hanging out in a tank together. But I think it is aggression. Practically speaking, not scary. Cause they're just saying, I make my tummy mad at you. Er, not scary.

But it might be maybe not even scary. It's just the way that they're mad. Like, you know, I feel like humans, if my friend was going, er, at me, I would be scared. was going Me you like he's there. Yes, yeah Okay, I get it. I I feel like you undersold the the the Choices fact in your fact, which is just that crabs have tummy teeth That's freaky to me and they have and they have apparently several like it Like it's not two, but it's not a ton. Yeah.

It sounded like it's maybe like three or four. I think so. I think, I couldn't tell. I'm just trying to look. I don't think they look quite like teeth, but if you look up gastric mills, then. Gastric mill, God. I'm not going to.

I think I see it. Ay, ay, ay. It looks like from the alien, from the Alien movie. All right. That's weird, Sari. I like it. Sam, what do you got? Small mammals like rodents have tiny, complicated,

fragile skeletons. That's as true now as it was a couple million years ago. Although it was also true a couple million years ago is that early humans were walking around, eating anything that we could get our grubby thumb having hands on. And this included plants and fish and large mammals, and most likely small mammals like rodents.

But due to the aforementioned tininess and fragileness of small mammal bones, researchers looking at ancient animal skeletons have a hard time telling if a small mammal died of natural causes and its skeleton was ravaged by the elements, or if a human ate a small animal and its skeleton was ravaged by stomach acid. And maybe also because of some modern day hangups about what is considered food and what isn't considered food by certain cultures, There hasn't been a ton of research into what human digestion does to rodent bones

in the same way that there's been research on things like fish bones, for instance. So long story short, there wasn't really a way to figure out if an early human ate a rodent that an archaeologist found. And not knowing that meant that not only do we not have a full picture of the life and habits of early humans, but we could also be missing out on like important sites of early human activity. So we have to figure out what's going on with these rodent skeletons that we find. And to do that, you have to observe the effect of human digestion on a rodent. But how do you do that?

Well, researchers Brian Crandall and Peter Stahl knew that there was kind of really only one way to do that. So they skinned and gutted and parboiled a shrew, cut it into thirds, and then fed it to a human volunteer who swallowed each of the three segments whole. And it was swallowed whole because the researchers just wanted to see how the stomach acid affected the skeleton. Who is this person? I don't know. I couldn't figure it out. Oh my gosh. But they're out there. He's out there. to see how the stomach acid affected the skeleton. Who is this person? I don't know, I couldn't figure it out. Oh my gosh.

But they're out there, he's out there. It's parboiled, so it's cooked. That means boiled very briefly, I believe. Yeah, just enough to kill all the whatever. And just took it like a pill. Yeah, just taking three shrew pills. Womp, womp, womp. And somebody else could chew it up later.

This guy was not chewing it up, he had science to do, that's not allowed science. The volunteer also ate what the paper describes as marker foods. Can you guess what that is? Just markers? No, it's corn. So that they would know in the same meal, he ate three pieces of shrew and some corn so that they see the corn and say, it's time for the shrew. So they found the corn, they found the shrew filled dookie when it came out of the guy two days later. Doesn't that seem like a long time? Two days?

That seems like a long time to me. So maybe he was just nervous. Crandall and Stahl, they then took a look at the shrew bones in the poop and observed the damage done in the digestion process and noted that damage that wasn't present in animals that died and decayed outside of a human being. So the most telling signs of human digestion seemed to mostly be in the shrew's teeth. So more of its teeth fell out in the digestion process and in the natural decaying process.

And the teeth had enamel damage from digestive juices so their teeth are all messed up. They only did this one time as far as I can tell, which also seems weird to me because if you're gonna feed one guy a shrew, you might as well just feed 50 people shrews. That's a really small sample size. Maybe they didn't want to dig through that much poop.

Maybe they're like, we'll see how one goes. I think they couldn't convince anyone else to eat a three piece shrew. Yeah. Well, you can convince one person to do it. Yeah, that's true. I think if there's one person who'll do it, there's kind of an infinite number. I honestly think if I was in college and somebody said, I'll pay you 50 bucks if you swallow this shrew. And give me your poop in two days.

And say, I'm so desperate and hungry. I'll do it. I'm so hungry. You mean I'll get free corn out of it too? Yeah, you got me at the corn. I wasn't into the corn. But to prove the work, the one guy's work, it proved valuable anyway, because in a 2013 interview,

which was conducted after this duo won the Ig Nobel Prize for this research, they said that their paper had been cited in about 50 archeological papers. So it all worked out for everybody. Can you really tell the difference that well? I think it seemed like the teeth is where the secret is and that the teeth looked different. Like the enamel damage is not something you'd ever. For archaeology. The enamel damage you'd never see anywhere else and it helped people figure out a human. This was in a human. I, oh boy, I have this job I have to do now.

I have to choose between the gruntings of the inner teeth of a crab or a man who ate a parboiled shrew that kills. And a bunch of corn too. And corn. I got to give it to Sam. Sari was like, well in the lead though. Is it that far in the lead? I think it is. to give it to Sam. Sari was like, well, in the lead, though, is it that far in the lead? I think it is. Oh, wow. Wow. I think it is.

I think the mark like a marker food, knowing what that is forever for the rest of my life is very useful. And then also the actual sort of archaeological need is real. So like that's one of the great things about the ignoble's is like it's not like dumb research People did for no reason. It's like dumb research that people did for good reasons. I don't know Sarah You don't look you don't like satisfied by my decision here I mean, I kind of knew it I see the Sam started describing the shrew and it's just such a good fact You can't

Tuna wrote that I got parboiled in the show flow, which is how I feel, I think. I know I was fighting the losing battle, but... Yeah. Parboiled and cut into thirds here on Session Tangents. At the end of the day, the people listening know more about crabs. And isn't that really what's important? Everybody won, except for Sari. Except Sari. Everybody in the whole world. If the whole world listened to the podcast, Sari still wouldn't win.

I won too because I got to hang out with my friends and apparently I've got to work to do that. It's really pathetic when people roll with the punches like that. So sad. All right. Now it is time to ask the science couch where we ask a listener question to our couch of finally honed scientific minds. Adam foot on Patreon and what it do baby on Twitter and make buzzer on YouTube asks, what is tummy rumbling? That's the funnest sentence I've ever in my life. What's the what's the like fun word for it?

Borboring. Yeah, there's a borb. Borborygmi? Borborygmuses. Borborygmi. I'm gonna let Sari take this one, because I don't know. I feel like you could guess. You're an expert on tummies. My brain says it's just like the muscles

of the stomach contracting. Yeah. And pushing stuff around a little bit. Is that what it is? Why do they do it harder sometimes than not other times? Are they just being like, what did you do? What have you done? Well, sometimes after you do it too,

then they'll say, excuse me. Yeah, the thing is, is your whole digestive system, esophagus, stomach downward, but really stomach downward is constantly muscling around, like squishing things through, whether you're digesting food, you squishing things through, whether you're digesting food, you're propelling solids, you're propelling liquids. There are gas bubbles around there gurgling. I'm suddenly conscious of it.

Yeah. It's happening right now. If you listen with a stethoscope, or even if you just like, I don't know, put your ear on someone else's tummy, you can hear it gurgling in there, even if it's quiet, not loud enough to hear outside. And that squeezing of the muscles is called peristalsis.

And basically it just, which just means kind of like how you'd squeeze out icing from a frosting tube or something like that. You're just, or toothpaste from a toothpaste tube. It's a contraction, a ring of contraction moving along your intestines and guts along the way. And there is a basic electrical rhythm that your nervous system regulates

that just kind of like squooshes things along. And then when you're hungry, there are specific types of peristalsis. The rate and the force varies, and it typically increases when you're hungry or in the presence of food. Like if you smell a cartoon smell of a chocolate chip cookie or a hot loaf of bread or something, then there's some combination of receptors throughout your nervous system, your sensory

nervous system, and receptors in the walls of your stomach that sense the absence of food, that you haven't had food in a little while. And that causes a generation of peristalsis waves called migrating myoelectric complexes or MMCs. And these MMCs are the hunger contractions and the tummy rumbles that you feel when you are hungry. And they start in the lower region of your stomach and then propagate along your gut, which is why you feel it in like your belly button area, even if though your stomach is up by your rib cages because your intestines are so long that these MMCs are propagating

along. And we think that it's partially as like a like a squeegee, kind of. It helps clear out anything else, like clears out extra mucus or remaining food cred or bacterial overgrowth to make room for your fresh next meal. Or is some sort of like. Reminding system, perhaps to say, you're hungry. Excuse me.

Excuse me. I love that. It's so, it feels, I like that feeling. Does anybody else like find that enjoyable? Like at least at first. Like in what way? Like it's a tickle? Yeah, it's just like, I'm gonna get to eat.

It surprises me usually. Surprises you? Yeah. Where it's like a reminder. It's like, oh no, I haven't eaten enough today. Yeah. So it's less of a, oh boy, I've got my next juicy meal lined up unless I'm like waiting for a big dinner or something where I'm intentionally just snacking throughout the day. And I'm like, okay, we're going to a buffet. We're going to a sushi buffet tonight. So I got to save up my tummy. This is something that I also I feel about a lot of my bodily functions are like your warning systems and stuff where it's like you like hit your hand finger with a hammer or something and then you're in pain. But you know, it's always just like, I know, I know, leave me alone. It's

like, I know I'm hungry. Just leave me alone. I want to take care of it. My stomach. Oh, man. I love it. I love being hungry. What the heck? I know. Like it says to me, like, oh, you did it. Oh, you used the tank of gas. Oh, yeah.

Time used all that you was doing. You did it. You used up all the food. Go get more. That's because oftentimes I don't go get more anyway. Yeah. Yeah. I'm just going to get more. That's nice. Because oftentimes I don't go get more anyway. Yeah. Yeah. I'm just going to get more. I'm like, I'm not hungry, but there's food over there.

You've really done it if you're hungry though. I guess I do feel that way after exercise, which is maybe says more about me as a person than in my relationship to my tummy grumbles of after I've exercised and I feel a tummy grumble, then I feel that, oh, I used up my gas feeling. I'm like, wow, I'm strong. We're all just dealing with various forms of shame,

it seems like. That's what I think, yeah. It's possible. You asked a silly question and now we're unpacking. We'll send this episode to my therapist later. All right, and now for our listeners on Patreon, we're gonna answer a bonus science couch question. Sam, what do we got?

Wasat86 on Twitter asked, why is communication between the stomach and brain so slow? Why can I be comfortably full, stop eating, and then be painfully over full five minutes later? If you wanna hear that answer to that question, as well as enjoy all new episodes totally ad-free, head over to our Patreon. That's patreon.com slash SciShow Tangents.

At our $8 a month tier, you get new episodes ad-free and extended shenanigans as we answer bonus science couch question every episode. You'll also get a link to join our private Discord server. Our patrons, you're the best. We're very grateful for your support of the show. If you want to ask the SciShow couch your question, you can follow us on Twitter at SciShowTangents, or check out our YouTube community tab where we'll send out topics for upcoming episodes every week. Or you can join the SciShowTangents Patreon and ask us on our Discord.

Thank you to at Quirky Viper, at Solock Holmes, and everybody else who asked us your questions for this episode. If you like this show and you want to help us out, it's really easy to do that. First, you can go to patreon.com slash SciShow Tangents to become a patron, get access to our new extended ad-free episodes, also shout out to patron Les Aker for their support. Second, you can leave us a review wherever you listen, that helps us know what you like about the show. And finally, if you want to show your love for SciShow Tangents, just tell people about us.

Thank you for joining us, I've been Hank Green. I've been Sari Reilly. And I've been Sam Schultz. SciShow Tangents is created by all of us and produced by Jess Stempert. Our associate producer is Eve Schmidt. Our editor is Seth Glicksman. Our social media organizer is Julia Buzz-Bazio. Our editorial assistants are Debuki Trakravarti and Alex Billo.

Our sound design is by Joseph Tuna-Medish. Our executive producers are Nicole Sweeney and me, Hank Green, and of course, we could not make any of this without our patrons on Patreon. Thank you, and remember, the mind is not a vessel to be filled, but a fire to be lighted. But one more thing! Ants use their stomachs to digest food, but they also use it to transport food and regurgitate it to share with friends. After Florida carpenter ants eat, they regularly lick their butts, or more specifically a hole, called the acidipore that lets them excrete the defensive chemical

formic acid. A 2020 study found that this butt-licking wasn't just a grooming behavior, it was actually helpful to increase their stomach acidity, protecting the ants from possible bad bacteria or other pathogens in their food and promoting good gut microbes. Florida carpenter ants swallow their own formic acid to help protect their stomachs. And it does come from their butt. I am so grateful that I don't have to eat rocks or drink goop out of my butt or any of that. Any of the other stuff we learned about. Eat a third of a parboiled shrew. Yeah, and everything's fine.

Yeah, eat my exoskeleton, eat my little clothes to help digest. I would eat my exoskeleton. Don't roll me up. I wish my tummy could growl at people. Yeah, there are some things you can't do. But nobody's scared about that. Our stomachs are a little boring,

but at least they're predictable. They're dependable. Yeah, I don't know what it would be like to be in there, but I bet it'd be weird. That's honestly one of my worst fears in the entire world is being eaten and digested alive. Yeah. Some people love more and Sam is here.

I'm not that guy.