How do crocodiles chomp?
32:04 Share

Hey educators! Do you want to help your students learn more about what's going on in the world outside your classroom? Why do leaves change colors in the fall? Why do animals hibernate? How do birds know when to migrate? Check out But Why Adventures. Our series, Northeast Nature, explores the science of what's on the landscape each month.

Learn more about plants, animals, and changing seasons in our series for educators and students. If you want to get But Why for your classroom or home study, sign up for But Why Adventures Northeast Nature. We'll send you monthly videos and activity guides for students. It's free, and you can find out more and sign up at butwhykids.org slash nature.

But why is supported by Progressive? Progressive helps you compare direct auto rates from a variety of companies so you can find a great one, even if it's not with them. Quote today at Progressive.com to find a rate that works with your budget. Progressive Casualty Insurance Company and Affiliates. Comparison rates not available in all states or situations. ♪♪

This is But Why, a podcast for curious kids from Vermont Public. I'm Jane Lindholm. On this show, we take questions from curious kids just like you, and we find answers. You send us a lot of questions about animals, and that is A-OK with me, because if you haven't already guessed, I love animals too.

When I was a kid, I wanted to be a marine biologist, a journalist, and a zookeeper. Well, I guess one out of three ain't bad, right? Anyway, I have always loved learning about animals, and so do Melody and Kiana, and so we are more than happy to tackle all of your animal questions.

The animals we're going to talk about today are not the cute and cuddly kind, but they are still fascinating and even beloved in their own way. We're learning about crocodilians, and we're going to learn about them from a researcher who knows a lot about reptiles. I'm Dr.

I'm Dr. Venetia Briggs-Gonzalez, and I am at the University of Florida with the CrocDocs Lab at Fort Lauderdale Research and Education Center. As she mentioned, Venetia Briggs-Gonzalez, who likes to go by Dr. V, is part of a group of researchers known as the CrocDocs. So the CrocDocs, it's a really cool story, actually. It goes back to like very early 1970s. My

My boss, Dr. Frank Mazzotti, he was out with a journalist and there was a hatchling crocodile that wasn't doing so well and he gave it mouth-to-mouth CPR and the journalist at the time dubbed him the original croc doctor and it stuck many, many years later. Most of you aren't giving mouth-to-mouth to crocodiles though. You're not treating them like a vet would.

Usually. Not usually. Although I can't say that we have not kissed them. You know, some folks are always looking for that prince on the other side. It might be in the form of a crocodile. Kids, I don't recommend kissing any crocodiles. Whatever Dr. B says, that's fine. But please don't go kissing crocodiles. So when we talk about crocs, we're not actually just talking about crocodiles. You're talking about crocodilians. Who are the crocodilians?

So the crocodilians are a really big group of animals, but they all essentially look the same and are super closely related. So crocodiles, alligators, caiman, who are just very similar, and gharials. So gharials have that really long snout. They are all crocodilians. Typically when we say crocs, though, I think we are actually referring to crocodiles. What do you have here in southern Florida?

Oh, we've got it all. In southern Florida, we have our native species, which are the American crocodile and the American alligator. We have a few species of invasive caiman here that we have been removing because they do cause harm to the native wildlife. We do not have gharials. Gharials are only found in India.

Where are caiman usually found? Where is their native habitat? So native caiman are found in South America. Everything is brought to South Florida as pets and released when they get really big. We've actually done a whole episode about invasive species and specifically some of the reptiles, like caiman, that have made South Florida their home.

Invasive plants and animals can cause a lot of problems for the wildlife that is indigenous to the area. And if you want to learn about some of the ways to prevent the spread of invasive species, go back and listen to that episode. Now, you've sent us quite a few questions about crocodilians, so we asked Dr. V if she'd take a crack at answering them. Hi, my name is Quinton, and I am six and a half years old.

and they live in Alaska Anchorage. And my question is, why do lizards have scales? My name is Otis. I live in Torquay, Australia, and I'm six months and seven. And my question is, why do lizards have scales? Hi, my name is Rowan. I am six years old. I live in Houston, Texas. And my question is,

Why do lizards have scales? All lizards do have scales, and they have them to serve a variety of purposes. Because lizards are considered cold-blooded, that means they do not generate their own body heat. They have to absorb the heat from the surface that they're on, or from the sunshine, or from whatever is around in their environment. So the scales help to keep the warmth in, and also helps to keep them cool on days when it's not very, very warm.

Scales also help to protect them. It's a defense mechanism. Scales are tough to break through, bite through, cut through. And of course it also serves as camouflage. So scales have colors, it has pigments that are either structural or non-structural, and that can help them blend in or stand out and prove that either they're dangerous or noxious or not.

You mentioned that scales are helpful because lizards are cold-blooded, so they have to regulate their temperature by the outside factors around them. And there are a lot of kids who want to know why. I mean, that seems maybe challenging, especially for those of us warm-blooded creatures who don't need the sunlight to be able to maintain our body heat.

My name is Zara. I live in Calgary and I'm five and a half. Why are reptiles all cold-blooded? And my name's Evelyn. I'm six years old and why are lizards cold-blooded? So that takes us all the way back to evolution, right? And some animals evolved earlier than others. Lizards and reptiles evolved before we did as humans.

And they were able to adapt to the environment and live in their environment because they were able to generate their own heat from the environment. They can't get warm on their own, but they can lay on a really warm rock. And that's why in a lot of cases you can get a snake crossing the road at nighttime because it's trying to warm up. I'm Julian. I'm five. I'm from Houston, Texas. And my question is,

Why do lizards can stick their tongue out to their eye and we can't? My name is Agatha. I'm a six-year-old and I live in California. My question is, why do lizards and snakes and other reptiles

stick their tongues out very often. What they eat is what makes their tongue really long. Being able to touch your eye with your tongue, sure, that's kind of cool, but being able to touch a fly that's on the branch halfway across the room, now that's impressive, and that's what a lot of chameleons are actually able to do. Crocodiles do not stick their tongues out because crocodiles do not have the same type of tongue. They actually have more like a

depressed tongue that is almost solid state. And so it's not a movable structure at all. And they have an opening at the back of their throat that allows the water to stay out when their mouth is open. And then when they're eating, that little opening opens up.

they do not have the same functional tongue like we do or like some other cool lizards do. I'm Luke and my question is how do lizards grow their tails back? Hi, my name is Luis. I am 11 and I live in Fort Collins, Colorado and my question is how do lizards' tails grow back? Hello, my name is Lenka and my question is when a lizard's tail falls off, why does a new one grow?

I live in Jakarta, Indonesia. I'm six years old. And my question is, how do lizards grow their tails back? The types of lizards that can lose their tails have a built-in line of weak spots called a fracture plane along their tail. When a predator has them by the tail, the lizard can actually pull its muscles away from one another and drop the end of their tail that's in the predator's mouth.

Their bodies have also evolved to make sure that they don't lose blood when their tail falls off. It takes a while to regrow and doesn't always look as good as the original tail. But not all lizards and reptiles can regrow their tail.

Crocodilians cannot regenerate their tail. And that's actually how we can tell when they've been in, you know, perhaps they've been in a fight or something, is that we'll get animals that have lost a bit of their tail. And because we mark all of the crocodiles and alligators that we capture as part of our monitoring project,

we can see who they are based on the scoots that we've clipped off, but they do not regenerate their tail. Lots of other lizards do. Unfortunately, the gecko that I have at home does not regenerate his tail, much to my kiddo's chagrin because mommy caught his tail in the door. So poor little thing, he lost his tail, so now he kind of just looks like a long frog, but he's super sweet still. Hi, my name is Charlotte. I'm nine years old. I'm from Auckland, New Zealand, and my question is,

Is a crocodile a dinosaur? So the common term that we always say is that crocodiles are modern-day dinosaurs. They are the closest thing to what a dinosaur used to be, but they're technically not a dinosaur. In fact, dinosaurs and crocodiles and alligators all came from the same ancestor. They are called archosaurs, and

From that group, we had birds, we had crocodiles, and then we have, you know, things that became lizards eventually. So they're not dinosaurs, but they have been around for so long, they might as well be dinosaurs. Hi, my name is Matthew, and I am six years old, and I live in Salt Lake Beach, Florida. My question is, like, why did some...

like lizards and bugs. So how did they survive the ice age and meteor when dinosaurs just didn't?

So when you think of a dinosaur, right, you think of like this big lumbering creature, super huge, can't really hide anywhere, can't really make itself into a ball, can't really do a whole lot to like run away or fly away or get away from something that's coming. A cockroach,

something really small can hide in between a rock crevice. Their babies and their offspring are made into eggs that are super protected. They have protective cases. They are super resistant. So it's just in how they're built. They're made to be tough and

Perhaps the cockroach that we have now, it's not the same cockroach that was around back then, but they haven't changed very much. And as for why crocodile ancestors survived when so many other thundering lizard dinosaurs didn't?

Researchers think it may have something to do with the way crocodiles still survive today. They don't use up a lot of energy because they don't run or swim around much unless they have to, which means they can go a long time without eating. They can also go on land or in the water, and they don't mind living in total darkness. And I'm five years old, living in Bonomi, Wisconsin. And my question is, do crocodiles resist? As to when the mammoths walked?

They were definitely not walking side by side. Woolly mammoths need to be in very, very cold places. Crocodiles, even the ancient crocodiles way back when, Deinosuchus was actually the very first ancient crocodile. And to this day, crocodiles and alligators, or crocodilians as we refer to them, they have to be in warm places. They perhaps lived around the same time, but in very different places.

Hi, my name is Leo and I want to know what's the difference between alligators and crocodiles? A crocodile has a V-shaped snout, much more pointy. An alligator has a U-shaped snout. So that's the biggest difference. And if you were to look at them from the top down or from the side, we always say that a crocodile has a very toothy grin because you can see both the upper and lower teeth. Whereas in an alligator, you only see the bottom teeth.

And then of course the coloration, alligators tend to be much darker in color, almost black, whereas crocodiles can be olive green, maybe like a light tan or drab brown and that just has to go with where they live. You know, they're blending in, it's camouflaged, alligators live in areas that are marshes, dark waters, whereas crocodiles are out on the coast or in the estuaries where water is a little bit lighter and in some cases they're on the beach and they're blending in right that way with the sand.

Do all crocodiles live in salt water? All crocodiles can tolerate salt water, but they pretty much all live either very close to fresh water. Some of them actually, like the American crocodile, have to drink fresh water to survive. Whereas the Nile crocodile and crocodiles over in northern and southern Africa, they have a gland that can secrete

the salt so they can actually live in salt water. So our American crocodile certainly lives along the coast but they need to go up into the estuaries for water. Here in southern Florida you have both, right? Do they ever overlap? Are they high-fiving each other or are alligators and crocodiles living in separate neighborhoods? So South Florida is the only place in the world where both the American crocodile and the American alligator meet.

The only places happens, and you will see this if you go down to Everglades National Park, it's at the very end of the park where the salt water starts to meet the fresh water of the Everglades.

Alligators are in the Everglades in their freshwater system, in the marshes coming down through the sloughs, and then in some of the canals that have fragmented the area. And then the saltwater, the coastal areas where crocodiles would be nesting, they come up into these areas. So you will actually be able to see that. But that's the only place that they both exist. And they exist just fine. I think they...

They partition the area and the space and they are kind of like just ships passing in the night. So they're not hanging out together? They can hang out beside each other, but they're not going to be like major competitors. They could definitely just hang out. My name is Spencer and I live in Utipa, California and my age is six. And my question is how do all the days stick to me?

Alligator means in Latin, one who binds. So an alligator, when it grabs its prey, especially if it's a big prey, is going to grab it and wrap around it and then it's going to twist. And most of the time they do this underwater. Alligator is essentially like a way of saying la serta and lagarto, which are in Spanish, and it's kind of putting those two together. So it's, alligator sort of came from those two origins.

What about the word crocodile? Crocodile is actually an ancient Greek word from what they referred to the lizard of the Nile River. So it's crocodilis and it's just spelled with a K and it just means lizard. So that's where the word crocodile comes from, which is kind of neat. Coming up, we'll learn more about crocodiles and their very impressive chomping skills. And do you know what a nictitating membrane is? Stay tuned and you will.

This is But Why, a podcast for curious kids from Vermont Public. I'm Jane Lindholm. Do you hear that? That's the sound of baby crocodiles calling for their mother.

We've been learning about crocodilians with Venetia Briggs-Gonzalez, one of the croc docs at the University of Florida. Dr. V told us that one of the coolest experiences she has had studying crocodilians was when she got to hold a cluster of baby crocs for the first time. She was out in the field counting and measuring them for research, so holding the babies was part of the job.

Watching out for a fast-approaching adult crocodile who didn't want her to hold the babies was another important part of the job. Of course, you should never pick up baby crocodiles unless you too are part of a research team doing work on them. Dr. V is answering all the questions you've sent us about these amazing creatures, so let's learn a little bit now about their bodies, how strong their bite is, and their unique adaptations to their habitat.

My name is Jackson and I'm from Saginaw, Michigan. And my question is, why do alligators and piranhas have to live in fresh water? All species, all animals need water to survive in some form or fashion. And if you're able to survive without fresh water, then you have created that adaptation.

So piranhas, sure, they live in freshwater because that's where they were born. That's where they were made to live. If you put them in saltwater, they're not going to survive. Crocodiles, same thing. When they're little, they're in freshwater and they need to be in freshwater, at least the species we have in the U.S. Lots of other species can survive in saltwater, but they have to have special adaptations. So basically, animals usually evolve to live in

either freshwater or saltwater, depending on their needs for food and habitat. A few creatures have adapted to live in both, which is kind of amazing because it usually takes really different bodily systems to process saltwater and freshwater. I'm Elijah, and my question is...

Why are alligators' teeth so big and their mouth is so long? Dr. V answered this by talking about crocodiles, but it's basically the same thing for alligators too. A crocodile's way of dealing with the things that it needs to eat is to evolve this longer snout.

So each generation, each snout got a little bit longer and the teeth got stronger because they started to be able to eat bigger things. More things became available. Mammals started coming around. Things that have strong, heavy bones, they need to be able to break them and tear them really easily. They're not sitting down at a diner getting a big plate of food and just having everything served to them. They have to be able to hunt it. So they need to have the tools and for them, the tools are like this big, strong head with

with a long snout and really strong teeth, big teeth too. And why is there a difference then between the snouts of crocodiles and alligators and, like you mentioned, gharials that have those long, really thin snouts? So is there different prey that they are eating that has caused them to have slightly different jaw structures?

So the jaws and the snout structure for crocodiles, alligators and gharials, yes, they're very similar in function. Crocodiles, the way they hunt, they are more directed. So they're going to be hunting, they're swimming, they're hunting. Alligators are known for being more sit and wait predators. So something comes by, they can chomp on it. When you look at a video of a gharial eating, they are slashing through the water left and right like a sword.

Left, right, left, right. And so they're getting all the fish that they're slashing through and their mouth is just open. And they're kind of like shredding the fish as they're catching it. My name is David. I'm four years old. And my question is, why do alligators sort of look like mirrors in the back of them? Other animals like that have that.

crocodilians almost all of them have this same thing it's called a tapidum lucidum and what it is it's essentially like a third eye that these animals have it captures the light and it reflects light almost like a mirror and that's why we're able to see them at nighttime when we do our work because we only work at night when we're going out to do captures and surveys because their eyes are

reflect back red. It's not that they're glowing red, it's that they're reflecting the light that we're shining on them and it comes back to us as red. Whoa, that is so cool. And that thing that she mentioned that reflects the light back, the tapetum lucidum, that was a new vocabulary word for me. It turns out lots of animals have a tapetum lucidum, including deer, cats, some dogs, horses, and many other mammals. It helps with night vision.

Sadly, humans do not have a tapetum lucidum. My name is Teddy. My question is, how do crocodiles see? So crocodiles and alligators have eyes that are perched on top of their heads.

So when they're swimming in the water, they can still see out of the water. When we're in the water and we're swimming, we can't really see above the water and we sure can't see below the water unless we're wearing goggles. So crocodilians actually have another eyelid

and it's called a nictitating membrane, which is super cool. It kind of protects their eyes when they're swimming and it kind of serves the function of goggles. So it makes them see really, really clear and it slides over their eyes when they get under the water and when they come up out of the water,

that eyelid just slides away again. But the way crocodiles and alligators have their eyes on top of their head just allows them to see prey better, to also avoid danger, and to be able to escape really quickly. Yeah, because if you can imagine having eyes on top of your head, you don't have to have much of your body out of the water, but you can still see what's going on, and you're kind of hidden, which could be really good if you're trying to catch something. And I want you to imagine for a minute a nictitating membrane, because how...

cool would it be to be able to dive into a pool or a river or a lake or the ocean and have, instead of having to put on goggles, have a little eyelid that comes up and protects your eye from that water, but acts like a goggle so you can see underwater. I really wish I had a nictitating membrane. I would love to have one. That would be amazing because we love swimming.

Right? And imagine if you had these little tiny goggles that are attached to your eyes and you just turn them on and turn them off by blinking. That would be super cool. So it's got to be really cool to be a crocodile to be able to do that. My name is Owen and I'm three years old and I want to know what that is called.

Crocodiles chomp at their teeth and their jaws. They actually have these really big jaws. So they chomp by, you know, opening that really big, wide mouth. And interestingly, both crocodiles and alligators are not able to bite open.

they can only close and chomp down. So a chomping motion is always closing the jaws. So it has its mouth open before it goes to bite something. Right. So it'll open it, but the strength is the closing motion. Hello, my name is Daniel. I live in Potsdam, Pennsylvania. I'm seven years old.

And I want to know why do crocodiles have the strongest bite? For this question, Dr. V turned to her colleague, one of the people she works with, who had been sitting right next to us the whole time. My name is Dua Ansari, and I'm the laboratory manager here at the CrocDocs. Dua Ansari not only arranged this whole conversation between me and Dr. V...

But she also knows a lot about crocodilians herself. So yes, crocodiles all actually do have the strongest bite and that's because they have the largest jaw-closing muscle. If you're thinking of any animal, any bite, crocodiles take the record.

I do not want a croc to bite me at all. I'm Michael and I'm five. I live in Burlington, Vermont. I want to know why do crocodile's teeth stay sharp when they don't know how to brush their teeth and they don't have a toothbrush? Crocodile teeth, they stay sharp due to their teeth.

them constantly feeding. Because of the type of foods they're eating, the amount of foods they're eating, the frequency of their eating, every time they do eat, then it's, you know, a little bit of just sharpening or keeping those teeth optimal, you know, so they can feed. Alligators, they shed their teeth and they can actually also replace them. So this mechanism of shedding and replacing teeth also help in keeping their teeth sharp.

That was one of the questions I had. Are alligators at all like sharks, which are many species of sharks are known for losing teeth and having a whole new row come in. And it sounds like maybe alligators don't have rows of teeth waiting, but they do lose teeth and grow new ones. Yeah, that's correct. That term is actually called polyphiodontia. That's another big word. I like that one.

My name is Alex. I'm from Mobile, Alabama. My question is, why are crocodiles green? Back to Dr. V. Crocodiles are largely green. I mean, the color of their skin...

it matches where they're living. And a lot of them, you know, they all have to be close to water. Water tends to be more green than it is red or more green than it is blue. So their skin can change color just a little bit so they can be darker and they can be lighter. Typically if they're out in the sun and they're basking on the sand, crocodiles are a lighter color or maybe it's a colder day, they can turn a little bit darker to absorb more heat.

My name is Charlie and I'm six years old and I live in Michigan. I wanted to know why do crocodiles have to swim? Sounds like Charlie may have a little sibling who was not as excited to know the answer to why crocodiles have to swim as Charlie was.

Crocodiles are, you know, they're aquatic animals. They're an aquatic species. That means they're tied to water. And a lot of the things they eat are in the water. Crocodiles will eat birds, but the birds are close to the water in a lot of cases. They'll eat mice and rats that are running close to the water or on the shore. But the majority of what they eat are fish and things that live in the water.

Hi, my name is Pierce. I'm from Alexander, Virginia. I'm five years old. My question is, how many fish does a crocodile eat in one day? Pierce wants to know how many fish can a crocodile eat in one day. Crocodiles and alligators don't eat a lot of food because they are cold-blooded. If

they did not have to regulate their own temperature and spend the energy that they have in their body to warm up their stomach to digest that food. They'd be able to put down a whole lot more. An average crocodile will eat anywhere from a pound to maximum three pounds per day. So a crocodile could eat a lot more, but it is not able to because it has to take the energy that is running its body to digest that food because it is cold-blooded.

How much energy does it take to track down their food and hunt it down? When you think of like a snake, if a snake has just captured something to eat, there's that big ball in its tummy. And you can see that ball while it's digesting. It's going to take that snake several days to digest that.

kind of like a crocodile. They will eat bigger prey items. It's just going to take them a lot longer and they're going to be a lot slower. And while they're trying to digest that, they are not hunting or doing any kind of fast swimming at all. So if you're lucky enough to see an alligator or a crocodile, they may just be sunning themselves just by the water side, right? They're not always swimming around fast and getting around and doing things and rushing from here to there. They're

kind of seem lazy sometimes. Most of the time it's sunning, it's basking itself, it's trying to keep warm and it's just self-regulating. On average you see a crocodile or an alligator swimming very slowly, not going anywhere very fast, but they're watching. How did you get into this whole idea of spending your life studying crocodilians?

So I have always been fascinated by the outdoors. And as a kid, I would be, I would spend a lot of my weekends and after school time with my parents who were out and about collecting orchids, checking out cool places because I'm from Belize where we have lots of beautiful places. There's waterfalls and there's creeks and rivers and waterfalls.

gorgeous plants and animals just everywhere. So we spent a lot of time outside and I just fell in love with it. And as I got older, I wanted to make sure that that stuff stayed around. And I learned that there was this whole career in wildlife ecology and

and that I could be like a doctor, but it would be instead of being a veterinarian taking care of sick animals, it would be taking care of the environment and the ecosystem and making sure that it stays healthy for my kids and my kids' kids. I kind of like knowing that I can help them just a little bit because a lot of people are afraid of crocodiles and alligators and think that they're out there just to hurt people, and they're not. They could care less about us humans. They just want to go on about their day,

sun themselves, maybe get a little bit of fish, and just keep on being. Wow, I learned so much about crocodilians today, and I hope you learned something new too. After I talked with Dr. V, I drove over to Everglades National Park and actually saw both alligators and crocodiles. South Florida is the only place in the world where alligators and crocodiles share a habitat, so it was really cool to see them just 20 feet apart.

We have pictures up on our social media channels if you want to get an adult to help you take a look at them. Thanks to Venetia Briggs-Gonzalez and Dua Ansari of the Croc Docs at the University of Florida for sharing awesome knowledge of crocs and gators with us. Now, if you have a question about anything, have an adult help you record yourself asking it. Then send the file to questions at butwhykids.org. We need your first name, where you live and how old you are, and what your question is.

You can also check out our website, butwhykids.org, for full instructions. I wish we could answer all of your questions as quickly as you ask them, but there's only three of us working on But Why, so we can't get to them all.

Still, I love knowing what you're curious about. And if you ever have a question and then you wind up going and doing the research to find the answer yourself, send us a video and we'll put it up on our Instagram page. Those three people I mentioned that make But Why, they're me, Jane Lindholm, alongside Melody Beaudet and Kiana Haskin. Lots of other people help us make sure this show gets out to you all, including Vermont Public, where we make the show, and PRX, which distributes it.

And, of course, you recognize that music when we start the show that tells you, hey, but why is on? That was created by Luke Reynolds. We'll be back in two weeks with an all-new episode. Until then, stay curious. From PR.