Venus fly traps at the Minnesota Landscape Arboretum.
Molly Bloom
Most plants get the energy and nutrients they need from water, sunlight, air and soil. But carnivorous plants get key nutrients from a different source: bugs. We’ll find out how they do it and talk about the mystery of how venus fly traps snap shut. Plus: Two gardeners – one very experienced and one just starting out – offer their tips for growing venus fly traps.
So that’s plants, but what about animals? Carnivores are animals that only eat other animals – so how do they get the vitamins, minerals and fiber that we humans get from eating plants? We take a trip to a salad bar with some animal pals to find out.
Plus the answer to a new moment of um: if you plant a popcorn kernel, will it grow into a popcorn plant?
Audio Transcript
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CREW: You're listening to Brains On!, where we're serious about being curious.
CREW: Brains On! Is supported in part by a grant from the National Science Foundation.
[ELECTRONIC MUSIC]
This is Brains On! From American Public Media. I'm Molly Bloom, and my co-host today is Quinn from Eagan, Minnesota. Hi, Quinn.
QUINN: Hi, everybody.
MOLLY BLOOM: Quinn, today we're talking carnivores, both plant and animal, flora and fauna. A carnivore is something that only eats creatures. What is your favorite carnivorous animal?
QUINN: The owl. I really love owls. It's my spirit animal. And snowy owls can be very courageous because they build their nests on the ground where they may have to flee polar bears.
MOLLY BLOOM: What do owls usually eat?
QUINN: Mice. But great horned owls tend to eat skunks without getting sprayed. Maybe they'll get sprayed, but they do eat some amazing things.
MOLLY BLOOM: How did you get interested in owls?
QUINN: I just started reading books about them. And then I was like, oh my gosh, I love these. I really want to read more.
MOLLY BLOOM: So you're very curious about owls.
QUINN: Yes. And now, I like, learn every-- I've learned everything about owls.
MOLLY BLOOM: So you're pretty much an owl expert now.
QUINN: Yes.
MOLLY BLOOM: Very cool. We are going to start by talking about carnivorous plants, and I'm going to take this as an opportunity to do something I've always wanted to do.
[CINEMATIC MUSIC]
(ANNOUNCER VOICE) In a world where herbivores eat plants and carnivores eat animals comes a plant that eats animals. It's called a carnivorous plant. And I ask you, who could tame such a plant? Her name-- Cassidy.
CASSIDY: My name is Cassidy, and I live in Chino Hills. And I'm seven years old, and I'm in second grade.
QUINN: Cassidy grows Venus flytraps.
CASSIDY: Yes, I do.
MOLLY BLOOM: And what do these fearsome organisms look like?
CASSIDY: You know plants that have leaves-- let's just imagine there's a butterfly there that makes a little V. And then there's points on the butterflies little wings. That'd be it. That'd be a Venus flytrap.
MOLLY BLOOM: OK. So maybe fearsome isn't the best word to describe these carnivorous plants, but they are super cool. And Venus fly traps are just the tip of the iceberg.
RICK GARZA: Yeah, there's Venus flytrap. There's pitcher plants. There's the cobra lilies, bladders warts-- a lot of those are actually aquatic. And their traps are very similar to the Venus flytrap's in that they're rapid action traps. But very tiny, and they're underwater, so people don't see them too often.
So we've got those. And we've got sundews, and there's also butterworts.
MOLLY BLOOM: Ricky Garza is a horticulturist and gardener at the Minnesota Landscape Arboretum. He says carnivorous plants are found in wet boggy places.
RICK GARZA: And these places are hard to walk in. You could sink in the muck pretty quickly. So they're not very human-friendly sort of environments. But the plants find their little niche there.
MOLLY BLOOM: And these places also have acidic soil, which is a problem. Generally, plants get all the nutrients and energy they need from water, sun, air, and soil. But this acidic soil doesn't have the nutrients that plants require, particularly nitrogen. So carnivorous plants have found a workaround-- they get that nitrogen from bugs.
QUINN: Carnivorous plants use some pretty nifty tricks to convince insects to land on them.
RICK GARZA: So part of it's the color, and part of it is they have little nectar sources that they are dewdrops that they lure them in on-- A tasty little surprise for the insect.
MOLLY BLOOM: Once the plant has lured an insect with a tasty meal, the next step is to trap it. Different carnivorous plants do this in different ways. Sundews trap the insects between sticky pin-like stalks. Butterworts use a similar sticky substance to trap insects on their leaves. And pitcher plants are shaped like wells that are very hard to get out of.
RICK GARZA: The edge is very slippery, and they wind up slipping slightly down into the pitcher plant. Beyond that smooth spot there are downward pointing hairs. They actually get stabbed by these little hairs. So they're forced basically lower and lower down into the pit.
QUINN: And then there's the star of the carnivorous plant world, the Venus flytrap. The reason they get the most attention is because the way they trap their meals.
CASSIDY: You know those hairs that are on it? Flies go on to the Venus flytrap, right? Then it has to touch two trigger hairs, and then it'll close right up. It's kind of like a sensor.
MOLLY BLOOM: Exactly. So picture a clamshell or, like Cassidy described it, butterfly wings. Before the Venus flytrap catches an insect, it's open. Inside the two halves are six trigger hairs. If an insect touches two of the trigger hairs within 20 seconds, it snaps shut. And it snaps shut quickly, like fraction of a second quickly.
RICK GARZA: People are just amazed that a plant can move that rapidly. Whether you're young or old, I think it's fascinating.
QUINN: That leads to this very excellent question from Alden N. Nevada from Leavenworth, Washington.
ALDEN: How does Venus flytrap move? Since they are plants, they do not have muscles.
MOLLY BLOOM: It turns out it's still something of a mystery. Scientists aren't exactly sure what's happening after that trigger, but many think that it has something to do with water pressure inside the plant.
RICK GARZA: There's a rapid change in water pressure that's inside the leaf, and actually the tip of the leaf grows very quickly. The leaf blades on the Venus flytrap go from being convex to being concave, and that action makes the flytrap close.
MOLLY BLOOM: So a change in water pressure causes a change in the shape of the leaf, snapping the cage shut. Now, we know how they lure the bugs and how they trap the bugs. But what puts the carnivore in carnivorous plants?
SOLOMON: My name is Solomon, and I live in Ponca City, Oklahoma. My question is, how do Venus flytraps eat flies? They don't have a throat to swallow them.
MOLLY BLOOM: And they don't have a stomach to digest them.
QUINN: But they do have something else that we have-- digestive juices.
MOLLY BLOOM: When a Venus flytrap closes, it secretes acid and enzymes that break down the insect so the plant can absorb the nutrients inside. This process takes somewhere between 5 and 12 days. Once it's done, the trap opens back up, the wind or rain sweeps away the remaining exoskeleton, and the trap is ready for a new bug.
Generally, each trap closes about 10 to 12 times before it's no longer able to do that anymore. Then it stays open to help the plant with photosynthesis for two to three months, and then the plant can grow new traps to replace the old ones. Many other carnivorous plants also use these digestive juices to get nutrients from insects, but there are a few species that use something else, something we humans also have in our guts-- microorganisms.
RICK GARZA: The northern pitcher plant doesn't have the digestive fluids, and they actually rely on other microbes in the pitcher to break down the insect to make it more readily absorbable.
MOLLY BLOOM: Just like Cassidy, Ricky first started getting interested in carnivorous plants when he got his first Venus flytrap as a boy. And just like Ricky, Cassidy has come to care a lot about her little collection.
CASSIDY: It's like your own mini garden. And well, now that I think about it, it's kind of fun seeing how good it grows. It's kind of like, you know, kids-- like, it's kind of like kids growing up, but it's a plant.
QUINN: If you're interested in having your own Venus flytrap, here are some tips from Cassidy and Ricky.
CASSIDY: I got my first one last year. That one kind of died. But then we bought a couple more. So we have six now.
RICK GARZA: Most of them like full sunlight, warm temperatures, and pure water.
CASSIDY: I accidentally put the water that we drink into it on accident. I forgot. You're only supposed to use distilled water, or else it will die.
RICK GARZA: One thing about the Venus flytrap, it needs a dormant period. So that would mean putting it in your refrigerator, lower 30s to upper 30s, during the winter, for probably two or three months. They only live in 100-mile circumference area that straddles North and South Carolina, and that's their global population. And their habitat is diminishing very rapidly. So it's important that you're going to have a plant to know that it was responsibly grown and not collected or harvested from the wild.
MOLLY BLOOM: (ANNOUNCER VOICE) The world of carnivorous plants is diverse and fascinating, full of sticky, slippery traps, digestive enzymes, and microorganisms, on land and under water, big and small.
OK. That's enough of that. But these plants really are super cool and have adapted to live in a place where most plants can't.
[CHILDREN'S VOICES IN REVERSE]
We're going to hear about carnivorous animals in just a minute. But first, Quinn, I have something for your ears to digest. It's time for the mystery sound.
[ODD CACOPHONY]
CREW: (WHISPERING) Mystery sound.
MOLLY BLOOM: Here it is.
[SLURPING SOUNDS]
QUINN: What is your guess I think it would be a picture plant digesting or something with an animal drinking maybe.
MOLLY BLOOM: Excellent guess on animal drinking or maybe a pitcher plant digesting--
QUINN: A fly.
MOLLY BLOOM: --a fly. Those are all really good guesses. We're going to be back with the answer a little bit later.
[UPBEAT MUSIC]
We're working on a series coming up all about feelings.
QUINN: A whole spectrum of emotion.
MOLLY BLOOM: And we want to hear from our listeners. Our question for you today-- what happens in your body when you feel nervous? So Quinn, what does it feel like for you when you get nervous?
QUINN: It feels like I have goose bumps, and, like, I feel really embarrassed. And, like, I pretend smile or um, is everything OK.
MOLLY BLOOM: Like maybe you freeze up a little bit.
QUINN: I kind of blush and get a little embarrassed and goose bumps. And I kind of freeze for every word I do.
MOLLY BLOOM: Very interesting. Well, listeners, send your answer to this question, what does it feel like in your body when you get nervous, by heading to brainson.org/contact.
QUINN: While you're there, you can also submit mystery sounds, ideas, drawings, and questions, like this one--
ERIC. Hey, my name is Eric, and I'm from Rochester, Minnesota. My question is, if you planted a popcorn kernel, would it grow into a popcorn plant?
MOLLY BLOOM: We'll answer that during our Moment of Um! At the end of the show. Plus we'll read the latest group of listeners to be added to the Brain's Honor Roll.
QUINN: Keep listening.
You're listening to Brains On! I'm Quinn.
MOLLY BLOOM: And I'm Molly. We're going to switch gears from carnivorous plants to carnivorous animals. And we're going to answer this fascinating question--
CHAIM: Hi, my name is Chaim from Cardston, Alberta. And my question is we have to eat vegetables to be healthy-- why do carnivores not require the same nutrients and minerals found in vegetables?
MOLLY BLOOM: What a great question, Chaim.
QUINN: Yeah. It's clear that this is not a thing you will ever hear at a cheetah's dining room table--
CREW: Eat your vegetables, please.
CREW: Do I have to?
CREW: Yes.
CREW: Why?
CREW: Because vegetables provide you with essential vitamins, minerals, and fiber.
MOLLY BLOOM: OK. So there are a few reasons this conversation would never happen. First off, cheetahs don't speak English. They speak Cheetah. Also, cheetahs don't care for formal dining areas, much less tables.
QUINN: But most importantly, it's because they're carnivores!
MOLLY BLOOM: Carnivores are animals that eat other animals. Some examples are snakes--
[HISS]
Lions--
[RAWR]
And owls.
[HOO]
Humans--
CREW: Um, hello.
MOLLY BLOOM: As well as animals like chipmunks--
CREW: Chipmunk, chipmunk.
MOLLY BLOOM: Bears.
[GROWL]
And blue Jays--
CREW: Tweet tweet.
MOLLY BLOOM: --are omnivores. That means we eat both animals and plants. And then there's herbivores like elephants--
[ELEPHANT IMITATION]
Cows--
SPEAKER: Moo.
MOLLY BLOOM: And rabbits.
SPEAKER: Hop hop.
MOLLY BLOOM: They eat only plants. So imagine some animal pals going out for lunch at the hot new salad bar in town.
RABBIT: This salad bar is amazing. The carrots are cut into five different shapes. Did you just see them gazelle?
GAZELLE: Of course, Rabbit. You couldn't stop pointing at them.
RABBIT: Oh yeah.
GAZELLE: Their fresh grass selection is very impressive-- organic, gluten free, artisan cut. You can really taste the difference. Not to mention, oh, this fruit. So fresh.
MOUSE: Mouse loves fruit.
RABBIT: Hey, lion, what's up with the empty plate? Do you mean to tell me you couldn't find a single thing to eat from this eye-popping selection?
LION: Well, Rabbit, I'd say this place is more targeted at the herbivores among us.
RABBIT: Oh, right. Well, it was Gazelle's turn to pick the place.
GAZELLE: Don't blame me, he's just a picky eater. Besides, it has five starfish on Yowl, so you know the food is good.
LION: Actually, Gazelle, I couldn't eat that grass even if I wanted to, which I most certainly don't.
GAZELLE: What? But it was grown using no harmful pesticides by local farmers. It actually came from the front yard.
LION: My digestive tract is not built like yours. Mine is basically an elegant tube. In and out goes the food. You have a four-chambered stomach that allows you to break down the tough fibers of plants like grass with help from all those wonderful little microorganisms living in your gut.
And you, and rabbit, and mouse, all have places where those tough morsels can sit and be digested over time. Me, not so much. My food passes through at a much quicker pace. I even have a different set of microorganisms tailored to my [CLEARS THROAT] more refined tastes in food.
RABBIT: Bummer for you then. More for the mouse.
GAZELLE: Mouse, don't be rude. We need to find something for him to eat.
RABBIT: Yeah, Mouse. Maybe the server knows if this salad bar has any secret non-vegetarian options. I mean, they got to have something. Right, mouse? Mouse?
Mouse? Where'd you go? Wasn't she just here a second ago?
GAZELLE: I could have sworn. Maybe she went to go find the waitress. Yeah.
LION: Oh, odd. Well, I'm sure she'll turn up eventually. One way or another.
GAZELLE: Well, riddle me this, Lion. If you can't eat plants, how do you get all the vitamins, and minerals, and stuff that you need? I get that from my grass. It's chocked full of good stuff.
LION: Well, you know, there are vitamins and minerals in the things I eat too.
GAZELLE: Like what?
LION: Well, organs are very nutrient rich. And then there's bones-- a great source of calcium. Viscera isn't just a beautiful word, it tastes divine.
GAZELLE: Bones? Get a load of that, Rabbit. He eats bones. Rabbit? Now, rabbit too?
They're probably both in the bathroom. Yeah, they probably went to the bathroom.
LION: Sometimes I enjoy some fur too. [GULPS] My favorite, however, is the liver. Delicious.
GAZELLE: Yeah. So that sounds great. You know, I just remembered I have an appointment.
LION: Oh, really? Where?
GAZELLE: Somewhere else. Not here. Got to go.
[RAPID FOOTSTEPS]
LION: You know what? I'm full too. Till next time, Gazelle. Waitress, waitress, can I get the check? I think my friends won't be paying for their meals unfortunately.
CREW: (SINGING) Ba ba ba ba ba ba ba ba ba ba ba Brains On!
MOLLY BLOOM: So the reason carnivores don't need to eat their vegetables-- they can't process plants the way herbivores do, and they've evolved to get all the nutrients they need from the animals they eat. We're going to hear more about feeding animals in a little bit. But first we're going to feed your ears again. Let's go back to the mystery sound.
[SLURPING NOISES]
Any new thoughts, Quinn?
QUINN: Well, I still think that the pitcher plant digesting and I'm going to change the animal drinking something a little bit to a herbivore drinking.
MOLLY BLOOM: Interesting. OK, a herbivore drinking. I like that.
QUINN: Because I don't think there's any blood in there.
[LAUGHTER]
MOLLY BLOOM: Excellent guess. Well, here is the answer.
BELLA: My name is Bella from Kansas, and I am 10 years old. The sound you just heard was my potbelly pig Barbie eating her slop. Most of the time we feed her pig feed, but on occasions we feed her slop which is leftovers and old food most people throw away. Her favorite thing is old brown bananas. Barbie picks him up in her mouth, slurps up the banana part, and spits out the peel.
CREW: Brains, brains, Brains On!
MOLLY BLOOM: Pigs are omnivores. And as we just learned, omnivores, herbivores, and carnivores all have very different ways of digesting and getting the nutrients they need. In a place like the National Zoo in Washington DC, it's someone's job to make sure all the animals from ants to zebras get the right nutrition.
MIKE MASLANKA: My name is Mike Maslanka. I am the head of the Department of Nutrition Science for Smithsonian's National Zoological Park and the Conservation Biology institute.
QUINN: The carnivores there rely on Mike for their diet.
MIKE MASLANKA: In a zoological setting, when it comes to feeding carnivores, we can't feed out gazelles to our cheetahs. So what we do is we feed out commercial meat mixes that have nutrient profiles that kind of look like those gazelles. What we do is we have a ground beef that mixes in other nutrients that those carnivores need.
As with most solutions, they're not always perfect. And so, in this case, we also feed bone. And we also feed whole prey-- so things like rabbits, and rats, and mice. Because all of those things are important for us to provide a balanced diet and provide variety.
When these animals first came into zoo settings, they were fed carcass. And then because that was difficult, they migrated towards feeding them slab meat which is basically steak. And they weren't getting that calcium. So we had lions, and tigers, and cheetahs that had metabolic bone disease.
So then we created these commercial diets but they're soft diets and they don't require a lot of chewing. They meet all the nutrient needs. But from a behavioral standpoint and from a physical standpoint, they might not be meeting some other needs. So now we're coming all the way back to the beginning and saying, hey, maybe we ought to go back to feeding more carcass. Because it's better for these animals in terms of providing them with a wider variety of nutrients, more fiber, and then giving them something in a physical form that challenges them to eat.
It's interesting. Because every new case that we have, and every time that we really dig down deep into a new species, there are so many things to be excited about and learn about. One day we're working on how to feed a colony of leaf cutter ants, and the next day we're working on feeding zebras, and the next day it's Komodo dragons, and the next day it's migratory passerine birds.
[UPBEAT MUSIC]
[ELECTRONIC MUSIC]
MOLLY BLOOM: Carnivorous plants can use acid, enzymes, and sometimes microorganisms to break down the creatures they eat and absorb their nutrients.
QUINN: Carnivores only eat animals, herbivores only eat plants, and omnivores can eat both.
MOLLY BLOOM: Carnivorous animals have different digestive tracts than herbivores and omnivores.
QUINN: And they've evolved to get all the nutrients they need from eating other animals.
MOLLY BLOOM: That's it for this episode of Brains On!
QUINN: Brains On! Is produced by Molly Bloom, Mark Sanchez, and Sanden Totten.
MOLLY BLOOM: Menaka Wilhelm is the grooviest of Fellows. We had production help this week from Jackie Kim and engineering help from John Miller and Veronica Rodriguez. Many Thanks to Callie Menster, Julie Churchill, Eric Spaulding, Eric [INAUDIBLE], and Anna Weggel.
QUINN: Brains On! Is a nonprofit public media podcast, and your donations help keep the show going.
MOLLY BLOOM: Head to brainson.org/donate to give and see our cool thank you gifts.
QUINN: Now, before we go, it's time for the Moment of Um!
[CHORUS OF UMS]
ERIC: My question is if you planted a popcorn kernel, would it grow into a popcorn plant?
PHIL FOX: My name is Phil Fox. I'm the VP of Product Development at Popcornopolis. I'm also the Chief Food Scientist, the chief foodie, and we make lots of popcorn every day. So if you take a kernel of popcorn, it's going to grow. Definitely, it'll make a plant. But how good of a plant, you don't really know until you try.
So that has to do with the hybridization process or the crossbreeding process that a lot of modern popcorn companies use in terms of their seed. So I think the best thing to do would be to find an heirloom variety of popcorn. So an heirloom variety is a really ancient seed that's not been genetically modified, or hybridized, or anything like that. So it's the native seed that's been around for eons.
So after the kernel has grown, it needs to go through a drying process. So you may be thinking this plant looks like, well, a popcorn plant. It's really going to look more like a corn plant. So you can take that cob of corn off the plant, and you can remove the kernels, and then you'd have to dry them out a bit. So in order for this popcorn to look like that beautiful popcorn that you see around at the movie theater-- wherever-- it needs to go through that drying process.
So once it does that, then you could use it as popcorn. Put it in your microwave. Whatever you want to do.
MOLLY BLOOM: This list of names is popping. It's time for the Brains honor roll. These are the brilliant listeners who share their ideas, questions, mystery sounds, and drawings with us. They make this show what it is.
[LISTING HONOR ROLL]
(SINGING) Brains Honor Roll. Bye-bye.
QUINN: Thanks for listening!
CREW: Brains On! Is supported in part by a grant from the National Science Foundation.
[ELECTRONIC MUSIC]
This is Brains On! From American Public Media. I'm Molly Bloom, and my co-host today is Quinn from Eagan, Minnesota. Hi, Quinn.
QUINN: Hi, everybody.
MOLLY BLOOM: Quinn, today we're talking carnivores, both plant and animal, flora and fauna. A carnivore is something that only eats creatures. What is your favorite carnivorous animal?
QUINN: The owl. I really love owls. It's my spirit animal. And snowy owls can be very courageous because they build their nests on the ground where they may have to flee polar bears.
MOLLY BLOOM: What do owls usually eat?
QUINN: Mice. But great horned owls tend to eat skunks without getting sprayed. Maybe they'll get sprayed, but they do eat some amazing things.
MOLLY BLOOM: How did you get interested in owls?
QUINN: I just started reading books about them. And then I was like, oh my gosh, I love these. I really want to read more.
MOLLY BLOOM: So you're very curious about owls.
QUINN: Yes. And now, I like, learn every-- I've learned everything about owls.
MOLLY BLOOM: So you're pretty much an owl expert now.
QUINN: Yes.
MOLLY BLOOM: Very cool. We are going to start by talking about carnivorous plants, and I'm going to take this as an opportunity to do something I've always wanted to do.
[CINEMATIC MUSIC]
(ANNOUNCER VOICE) In a world where herbivores eat plants and carnivores eat animals comes a plant that eats animals. It's called a carnivorous plant. And I ask you, who could tame such a plant? Her name-- Cassidy.
CASSIDY: My name is Cassidy, and I live in Chino Hills. And I'm seven years old, and I'm in second grade.
QUINN: Cassidy grows Venus flytraps.
CASSIDY: Yes, I do.
MOLLY BLOOM: And what do these fearsome organisms look like?
CASSIDY: You know plants that have leaves-- let's just imagine there's a butterfly there that makes a little V. And then there's points on the butterflies little wings. That'd be it. That'd be a Venus flytrap.
MOLLY BLOOM: OK. So maybe fearsome isn't the best word to describe these carnivorous plants, but they are super cool. And Venus fly traps are just the tip of the iceberg.
RICK GARZA: Yeah, there's Venus flytrap. There's pitcher plants. There's the cobra lilies, bladders warts-- a lot of those are actually aquatic. And their traps are very similar to the Venus flytrap's in that they're rapid action traps. But very tiny, and they're underwater, so people don't see them too often.
So we've got those. And we've got sundews, and there's also butterworts.
MOLLY BLOOM: Ricky Garza is a horticulturist and gardener at the Minnesota Landscape Arboretum. He says carnivorous plants are found in wet boggy places.
RICK GARZA: And these places are hard to walk in. You could sink in the muck pretty quickly. So they're not very human-friendly sort of environments. But the plants find their little niche there.
MOLLY BLOOM: And these places also have acidic soil, which is a problem. Generally, plants get all the nutrients and energy they need from water, sun, air, and soil. But this acidic soil doesn't have the nutrients that plants require, particularly nitrogen. So carnivorous plants have found a workaround-- they get that nitrogen from bugs.
QUINN: Carnivorous plants use some pretty nifty tricks to convince insects to land on them.
RICK GARZA: So part of it's the color, and part of it is they have little nectar sources that they are dewdrops that they lure them in on-- A tasty little surprise for the insect.
MOLLY BLOOM: Once the plant has lured an insect with a tasty meal, the next step is to trap it. Different carnivorous plants do this in different ways. Sundews trap the insects between sticky pin-like stalks. Butterworts use a similar sticky substance to trap insects on their leaves. And pitcher plants are shaped like wells that are very hard to get out of.
RICK GARZA: The edge is very slippery, and they wind up slipping slightly down into the pitcher plant. Beyond that smooth spot there are downward pointing hairs. They actually get stabbed by these little hairs. So they're forced basically lower and lower down into the pit.
QUINN: And then there's the star of the carnivorous plant world, the Venus flytrap. The reason they get the most attention is because the way they trap their meals.
CASSIDY: You know those hairs that are on it? Flies go on to the Venus flytrap, right? Then it has to touch two trigger hairs, and then it'll close right up. It's kind of like a sensor.
MOLLY BLOOM: Exactly. So picture a clamshell or, like Cassidy described it, butterfly wings. Before the Venus flytrap catches an insect, it's open. Inside the two halves are six trigger hairs. If an insect touches two of the trigger hairs within 20 seconds, it snaps shut. And it snaps shut quickly, like fraction of a second quickly.
RICK GARZA: People are just amazed that a plant can move that rapidly. Whether you're young or old, I think it's fascinating.
QUINN: That leads to this very excellent question from Alden N. Nevada from Leavenworth, Washington.
ALDEN: How does Venus flytrap move? Since they are plants, they do not have muscles.
MOLLY BLOOM: It turns out it's still something of a mystery. Scientists aren't exactly sure what's happening after that trigger, but many think that it has something to do with water pressure inside the plant.
RICK GARZA: There's a rapid change in water pressure that's inside the leaf, and actually the tip of the leaf grows very quickly. The leaf blades on the Venus flytrap go from being convex to being concave, and that action makes the flytrap close.
MOLLY BLOOM: So a change in water pressure causes a change in the shape of the leaf, snapping the cage shut. Now, we know how they lure the bugs and how they trap the bugs. But what puts the carnivore in carnivorous plants?
SOLOMON: My name is Solomon, and I live in Ponca City, Oklahoma. My question is, how do Venus flytraps eat flies? They don't have a throat to swallow them.
MOLLY BLOOM: And they don't have a stomach to digest them.
QUINN: But they do have something else that we have-- digestive juices.
MOLLY BLOOM: When a Venus flytrap closes, it secretes acid and enzymes that break down the insect so the plant can absorb the nutrients inside. This process takes somewhere between 5 and 12 days. Once it's done, the trap opens back up, the wind or rain sweeps away the remaining exoskeleton, and the trap is ready for a new bug.
Generally, each trap closes about 10 to 12 times before it's no longer able to do that anymore. Then it stays open to help the plant with photosynthesis for two to three months, and then the plant can grow new traps to replace the old ones. Many other carnivorous plants also use these digestive juices to get nutrients from insects, but there are a few species that use something else, something we humans also have in our guts-- microorganisms.
RICK GARZA: The northern pitcher plant doesn't have the digestive fluids, and they actually rely on other microbes in the pitcher to break down the insect to make it more readily absorbable.
MOLLY BLOOM: Just like Cassidy, Ricky first started getting interested in carnivorous plants when he got his first Venus flytrap as a boy. And just like Ricky, Cassidy has come to care a lot about her little collection.
CASSIDY: It's like your own mini garden. And well, now that I think about it, it's kind of fun seeing how good it grows. It's kind of like, you know, kids-- like, it's kind of like kids growing up, but it's a plant.
QUINN: If you're interested in having your own Venus flytrap, here are some tips from Cassidy and Ricky.
CASSIDY: I got my first one last year. That one kind of died. But then we bought a couple more. So we have six now.
RICK GARZA: Most of them like full sunlight, warm temperatures, and pure water.
CASSIDY: I accidentally put the water that we drink into it on accident. I forgot. You're only supposed to use distilled water, or else it will die.
RICK GARZA: One thing about the Venus flytrap, it needs a dormant period. So that would mean putting it in your refrigerator, lower 30s to upper 30s, during the winter, for probably two or three months. They only live in 100-mile circumference area that straddles North and South Carolina, and that's their global population. And their habitat is diminishing very rapidly. So it's important that you're going to have a plant to know that it was responsibly grown and not collected or harvested from the wild.
MOLLY BLOOM: (ANNOUNCER VOICE) The world of carnivorous plants is diverse and fascinating, full of sticky, slippery traps, digestive enzymes, and microorganisms, on land and under water, big and small.
OK. That's enough of that. But these plants really are super cool and have adapted to live in a place where most plants can't.
[CHILDREN'S VOICES IN REVERSE]
We're going to hear about carnivorous animals in just a minute. But first, Quinn, I have something for your ears to digest. It's time for the mystery sound.
[ODD CACOPHONY]
CREW: (WHISPERING) Mystery sound.
MOLLY BLOOM: Here it is.
[SLURPING SOUNDS]
QUINN: What is your guess I think it would be a picture plant digesting or something with an animal drinking maybe.
MOLLY BLOOM: Excellent guess on animal drinking or maybe a pitcher plant digesting--
QUINN: A fly.
MOLLY BLOOM: --a fly. Those are all really good guesses. We're going to be back with the answer a little bit later.
[UPBEAT MUSIC]
We're working on a series coming up all about feelings.
QUINN: A whole spectrum of emotion.
MOLLY BLOOM: And we want to hear from our listeners. Our question for you today-- what happens in your body when you feel nervous? So Quinn, what does it feel like for you when you get nervous?
QUINN: It feels like I have goose bumps, and, like, I feel really embarrassed. And, like, I pretend smile or um, is everything OK.
MOLLY BLOOM: Like maybe you freeze up a little bit.
QUINN: I kind of blush and get a little embarrassed and goose bumps. And I kind of freeze for every word I do.
MOLLY BLOOM: Very interesting. Well, listeners, send your answer to this question, what does it feel like in your body when you get nervous, by heading to brainson.org/contact.
QUINN: While you're there, you can also submit mystery sounds, ideas, drawings, and questions, like this one--
ERIC. Hey, my name is Eric, and I'm from Rochester, Minnesota. My question is, if you planted a popcorn kernel, would it grow into a popcorn plant?
MOLLY BLOOM: We'll answer that during our Moment of Um! At the end of the show. Plus we'll read the latest group of listeners to be added to the Brain's Honor Roll.
QUINN: Keep listening.
You're listening to Brains On! I'm Quinn.
MOLLY BLOOM: And I'm Molly. We're going to switch gears from carnivorous plants to carnivorous animals. And we're going to answer this fascinating question--
CHAIM: Hi, my name is Chaim from Cardston, Alberta. And my question is we have to eat vegetables to be healthy-- why do carnivores not require the same nutrients and minerals found in vegetables?
MOLLY BLOOM: What a great question, Chaim.
QUINN: Yeah. It's clear that this is not a thing you will ever hear at a cheetah's dining room table--
CREW: Eat your vegetables, please.
CREW: Do I have to?
CREW: Yes.
CREW: Why?
CREW: Because vegetables provide you with essential vitamins, minerals, and fiber.
MOLLY BLOOM: OK. So there are a few reasons this conversation would never happen. First off, cheetahs don't speak English. They speak Cheetah. Also, cheetahs don't care for formal dining areas, much less tables.
QUINN: But most importantly, it's because they're carnivores!
MOLLY BLOOM: Carnivores are animals that eat other animals. Some examples are snakes--
[HISS]
Lions--
[RAWR]
And owls.
[HOO]
Humans--
CREW: Um, hello.
MOLLY BLOOM: As well as animals like chipmunks--
CREW: Chipmunk, chipmunk.
MOLLY BLOOM: Bears.
[GROWL]
And blue Jays--
CREW: Tweet tweet.
MOLLY BLOOM: --are omnivores. That means we eat both animals and plants. And then there's herbivores like elephants--
[ELEPHANT IMITATION]
Cows--
SPEAKER: Moo.
MOLLY BLOOM: And rabbits.
SPEAKER: Hop hop.
MOLLY BLOOM: They eat only plants. So imagine some animal pals going out for lunch at the hot new salad bar in town.
RABBIT: This salad bar is amazing. The carrots are cut into five different shapes. Did you just see them gazelle?
GAZELLE: Of course, Rabbit. You couldn't stop pointing at them.
RABBIT: Oh yeah.
GAZELLE: Their fresh grass selection is very impressive-- organic, gluten free, artisan cut. You can really taste the difference. Not to mention, oh, this fruit. So fresh.
MOUSE: Mouse loves fruit.
RABBIT: Hey, lion, what's up with the empty plate? Do you mean to tell me you couldn't find a single thing to eat from this eye-popping selection?
LION: Well, Rabbit, I'd say this place is more targeted at the herbivores among us.
RABBIT: Oh, right. Well, it was Gazelle's turn to pick the place.
GAZELLE: Don't blame me, he's just a picky eater. Besides, it has five starfish on Yowl, so you know the food is good.
LION: Actually, Gazelle, I couldn't eat that grass even if I wanted to, which I most certainly don't.
GAZELLE: What? But it was grown using no harmful pesticides by local farmers. It actually came from the front yard.
LION: My digestive tract is not built like yours. Mine is basically an elegant tube. In and out goes the food. You have a four-chambered stomach that allows you to break down the tough fibers of plants like grass with help from all those wonderful little microorganisms living in your gut.
And you, and rabbit, and mouse, all have places where those tough morsels can sit and be digested over time. Me, not so much. My food passes through at a much quicker pace. I even have a different set of microorganisms tailored to my [CLEARS THROAT] more refined tastes in food.
RABBIT: Bummer for you then. More for the mouse.
GAZELLE: Mouse, don't be rude. We need to find something for him to eat.
RABBIT: Yeah, Mouse. Maybe the server knows if this salad bar has any secret non-vegetarian options. I mean, they got to have something. Right, mouse? Mouse?
Mouse? Where'd you go? Wasn't she just here a second ago?
GAZELLE: I could have sworn. Maybe she went to go find the waitress. Yeah.
LION: Oh, odd. Well, I'm sure she'll turn up eventually. One way or another.
GAZELLE: Well, riddle me this, Lion. If you can't eat plants, how do you get all the vitamins, and minerals, and stuff that you need? I get that from my grass. It's chocked full of good stuff.
LION: Well, you know, there are vitamins and minerals in the things I eat too.
GAZELLE: Like what?
LION: Well, organs are very nutrient rich. And then there's bones-- a great source of calcium. Viscera isn't just a beautiful word, it tastes divine.
GAZELLE: Bones? Get a load of that, Rabbit. He eats bones. Rabbit? Now, rabbit too?
They're probably both in the bathroom. Yeah, they probably went to the bathroom.
LION: Sometimes I enjoy some fur too. [GULPS] My favorite, however, is the liver. Delicious.
GAZELLE: Yeah. So that sounds great. You know, I just remembered I have an appointment.
LION: Oh, really? Where?
GAZELLE: Somewhere else. Not here. Got to go.
[RAPID FOOTSTEPS]
LION: You know what? I'm full too. Till next time, Gazelle. Waitress, waitress, can I get the check? I think my friends won't be paying for their meals unfortunately.
CREW: (SINGING) Ba ba ba ba ba ba ba ba ba ba ba Brains On!
MOLLY BLOOM: So the reason carnivores don't need to eat their vegetables-- they can't process plants the way herbivores do, and they've evolved to get all the nutrients they need from the animals they eat. We're going to hear more about feeding animals in a little bit. But first we're going to feed your ears again. Let's go back to the mystery sound.
[SLURPING NOISES]
Any new thoughts, Quinn?
QUINN: Well, I still think that the pitcher plant digesting and I'm going to change the animal drinking something a little bit to a herbivore drinking.
MOLLY BLOOM: Interesting. OK, a herbivore drinking. I like that.
QUINN: Because I don't think there's any blood in there.
[LAUGHTER]
MOLLY BLOOM: Excellent guess. Well, here is the answer.
BELLA: My name is Bella from Kansas, and I am 10 years old. The sound you just heard was my potbelly pig Barbie eating her slop. Most of the time we feed her pig feed, but on occasions we feed her slop which is leftovers and old food most people throw away. Her favorite thing is old brown bananas. Barbie picks him up in her mouth, slurps up the banana part, and spits out the peel.
CREW: Brains, brains, Brains On!
MOLLY BLOOM: Pigs are omnivores. And as we just learned, omnivores, herbivores, and carnivores all have very different ways of digesting and getting the nutrients they need. In a place like the National Zoo in Washington DC, it's someone's job to make sure all the animals from ants to zebras get the right nutrition.
MIKE MASLANKA: My name is Mike Maslanka. I am the head of the Department of Nutrition Science for Smithsonian's National Zoological Park and the Conservation Biology institute.
QUINN: The carnivores there rely on Mike for their diet.
MIKE MASLANKA: In a zoological setting, when it comes to feeding carnivores, we can't feed out gazelles to our cheetahs. So what we do is we feed out commercial meat mixes that have nutrient profiles that kind of look like those gazelles. What we do is we have a ground beef that mixes in other nutrients that those carnivores need.
As with most solutions, they're not always perfect. And so, in this case, we also feed bone. And we also feed whole prey-- so things like rabbits, and rats, and mice. Because all of those things are important for us to provide a balanced diet and provide variety.
When these animals first came into zoo settings, they were fed carcass. And then because that was difficult, they migrated towards feeding them slab meat which is basically steak. And they weren't getting that calcium. So we had lions, and tigers, and cheetahs that had metabolic bone disease.
So then we created these commercial diets but they're soft diets and they don't require a lot of chewing. They meet all the nutrient needs. But from a behavioral standpoint and from a physical standpoint, they might not be meeting some other needs. So now we're coming all the way back to the beginning and saying, hey, maybe we ought to go back to feeding more carcass. Because it's better for these animals in terms of providing them with a wider variety of nutrients, more fiber, and then giving them something in a physical form that challenges them to eat.
It's interesting. Because every new case that we have, and every time that we really dig down deep into a new species, there are so many things to be excited about and learn about. One day we're working on how to feed a colony of leaf cutter ants, and the next day we're working on feeding zebras, and the next day it's Komodo dragons, and the next day it's migratory passerine birds.
[UPBEAT MUSIC]
[ELECTRONIC MUSIC]
MOLLY BLOOM: Carnivorous plants can use acid, enzymes, and sometimes microorganisms to break down the creatures they eat and absorb their nutrients.
QUINN: Carnivores only eat animals, herbivores only eat plants, and omnivores can eat both.
MOLLY BLOOM: Carnivorous animals have different digestive tracts than herbivores and omnivores.
QUINN: And they've evolved to get all the nutrients they need from eating other animals.
MOLLY BLOOM: That's it for this episode of Brains On!
QUINN: Brains On! Is produced by Molly Bloom, Mark Sanchez, and Sanden Totten.
MOLLY BLOOM: Menaka Wilhelm is the grooviest of Fellows. We had production help this week from Jackie Kim and engineering help from John Miller and Veronica Rodriguez. Many Thanks to Callie Menster, Julie Churchill, Eric Spaulding, Eric [INAUDIBLE], and Anna Weggel.
QUINN: Brains On! Is a nonprofit public media podcast, and your donations help keep the show going.
MOLLY BLOOM: Head to brainson.org/donate to give and see our cool thank you gifts.
QUINN: Now, before we go, it's time for the Moment of Um!
[CHORUS OF UMS]
ERIC: My question is if you planted a popcorn kernel, would it grow into a popcorn plant?
PHIL FOX: My name is Phil Fox. I'm the VP of Product Development at Popcornopolis. I'm also the Chief Food Scientist, the chief foodie, and we make lots of popcorn every day. So if you take a kernel of popcorn, it's going to grow. Definitely, it'll make a plant. But how good of a plant, you don't really know until you try.
So that has to do with the hybridization process or the crossbreeding process that a lot of modern popcorn companies use in terms of their seed. So I think the best thing to do would be to find an heirloom variety of popcorn. So an heirloom variety is a really ancient seed that's not been genetically modified, or hybridized, or anything like that. So it's the native seed that's been around for eons.
So after the kernel has grown, it needs to go through a drying process. So you may be thinking this plant looks like, well, a popcorn plant. It's really going to look more like a corn plant. So you can take that cob of corn off the plant, and you can remove the kernels, and then you'd have to dry them out a bit. So in order for this popcorn to look like that beautiful popcorn that you see around at the movie theater-- wherever-- it needs to go through that drying process.
So once it does that, then you could use it as popcorn. Put it in your microwave. Whatever you want to do.
MOLLY BLOOM: This list of names is popping. It's time for the Brains honor roll. These are the brilliant listeners who share their ideas, questions, mystery sounds, and drawings with us. They make this show what it is.
[LISTING HONOR ROLL]
(SINGING) Brains Honor Roll. Bye-bye.
QUINN: Thanks for listening!
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