What's the Difference Between a Turtle and a Tortoise?

Transcript

ERIC: Turtles are some of the most amazing animals in the world. The same can be said of tortoises. But what's the difference? Today on Pulsar we'll explore that question as well as other popular queries that we get about our shelled residents. Often at the museum, when you see a tortoise, you also see Karen, one of our educators, teaching crowds about its adaptations while it moves slowly across the stage. So I thought she would be perfect to answer all of your turtle and tortoise questions. Karen, thanks for coming back on the podcast.

KAREN: Hey Eric, I'm so happy to be here again.

ERIC: So it's one of those questions you hear a lot. We've got it a lot at the museum. Let's just start with it. What is the difference between a turtle and a tortoise?

KAREN: That's a question we get asked a lot, whether it's in some of our livestreams we've been doing over the past year, whether it's at the museum, or even when we're out visiting schools with our live animal collection, people always want to know what is the difference between a turtle and a tortoise. Are they the same, are they different? And I'm going to start by saying something that might sound confusing. All tortoises are turtles, but not all turtles are tortoises. Along the same lines is all toads are frogs, but not all frogs are toads. And for the non-biologists listening in today, all squares are rectangles. Not all rectangles are squares.

ERIC: So a tortoise is a kind of turtle.

KAREN: Exactly. So it's sort of like a subgroup. So if you were looking at something that you thought: is it a turtle is it a tortoise? You could call it a turtle and be correct. If you wanted to be a little bit more specific, you could call it a tortoise. And there are some things that you can look for that make tortoises just a little bit different than turtles, hence why they're a subgroup. And some of those are: they tend to be mostly terrestrial, meaning tortoises tolerate dryer temperatures, you don't find them living in ponds, and rivers and oceans. They are not like a snapping turtle. They're not like a sea turtle. You find them walking around on the ground. They also. because of that, have some features about their body can help you identify it. They have what we call elephantine feet. If you can picture what the foot of an elephant looks like, and just kind of shrink that down and stick it on a tortoise. Kind of squared off and clunky. Pretty flat claws or flat nails, they're not very sharp and pointy, because they often spend a lot of time digging. So they use those flat claws and those clunky feet to get over ground. Another distinguishing characteristic that might make it a tortoise is usually they have higher domed shells. So if you can picture like a sea turtle in your head, they have pretty flat, streamlined shells. Really great for going through the water in the ocean. Helps them get up that speed when they're swimming. Tortoise on the other hand, living in drier environments, has that high domed shell and that helps them store up extra water. So even if they're in an area like desert that doesn't get a lot of water, they can store it up inside of their bodies. But those are kind of the easiest ways to tell the difference. I will admit there are some tricky ones. As always, there are exceptions.

ERIC: Always exceptions to every nice, simple rule. Every time we try to categorize anything, there's always something that doesn't fit.

KAREN: Yeah, we have a species that lives at the museum called a box turtle. It's local here to the northeast. Actually, pretty much down the whole East Coast of the United States. It has a high domed shell, it actually closes up like a box. Hence the name box turtle. They have pretty clunky feet. But they're called box turtles, not tortoises. But if you do see one of those out there in the wild, again, call it a turtle. It kind of covers the whole overarching group.

ERIC: So basically, if you see a turtle and you want to know if it's a tortoise, look to see if it has that domed shell, look to see if that has those feet like an elephant, and look where it is. Because if it seems like it mostly lives on the land, it might be a tortoise.

KAREN: Exactly.

ERIC: What kind of turtles and tortoises do we have at the museum? Which ones do you work with?

KAREN: So we have a handful of different species. We have several different types of turtles. Those box turtles that I mentioned, as well as wood turtles, which are another local New England if you're listening here in New England or local here. Wood turtles, side note, are really cool because they dance for their dinner. So they sort of do a little dance on the ground, and that makes the worms underneath the dirt think that it's raining. So they come up to the surface so they don't drown. And then they get eaten by the wood turtle.

ERIC: That's so cool. I didn't know that.

KAREN: It's one of my favorite stories. I remember years ago when I was working at an environmental summer camp. We actually got to see the educational wood turtle. We headed out on the forest floor and it started doing its little thumping, stamping its feet. It was one of the cutest things I've ever seen. And then we do have two species of tortoise. We have the desert tortoise, which is native to Mojave and Sonoran Desert, so sort of Southwest United States into northern parts of Mexico. And we also have two red footed tortoises that are native to the rainforests of South America. So they're also ground dwelling, but in very humid environments, as opposed to desert tortoise in very dry environments.

ERIC: So they live in a lot of different environments. That's kind of a question we get no matter what animal we have, where does it live? We also get asked, what do they eat? So specifically, tortoises, one of maybe the tortoise you work with? What kind of foods does it eat?

KAREN: So the species that I work with most in the turtle group at the museum is that desert tortoise. We have one individual. Her name is Sonora. Desert tortoises only eat plants. So in the desert where they natively live would eat things like grasses and wild flowers when they bloomed. A couple times a year when the rains come in the cacti produce their flowers and fruit - they would munch down on that. Here at the museum she gets fed a salad. So it's a mix of greens, kale, lettuce, dandelion greens. She also gets rotation of different types of fruits. I've seen things like cantaloupe, I have seen carrots, tomatoes I think get mixed in. What I really get jealous is when she has a nice salad including strawberries when they're in the offseason, and they are hard to find. So we treat our tortoises very well at the Museum of Science. Now other species of tortoise, they're not all herbivores. So our other tortoises, the red footed tortoises, are what we call opportunistic omnivores. Now an omnivore is an animal that can handle eating both plants and meat. Our tortoises are a sort of opportunistic omnivore which means that if they stumble across a worm or stumble into an ant, they might eat it. They're not hunting these other animals, so they mostly feed on plants. Now, something like a snapping turtle is a true omnivore, they eat anything they come across. So they'll eat plant matter. They'll catch a mouse, they'll catch a fish or a shrimp in the water. They also are very well known for eating carrion, which is dead, decaying meat. So snapping turtles actually help clean up the environment of animals that have passed along.

ERIC: Yeah, and some of the tortoises you'd think, you know, the stereotype is the tortoise and the hare. And you would think that putting that salad in front of the tortoise you work with, it would eat it really slowly. And it really doesn't, it just kind of bites away at that salad until it's gone.

KAREN: Yeah, they are hungry critters.

ERIC: So I got this idea for the podcast the other day, when I was watching you do your turtle show for a school group and you were talking about their adaptations. So can you talk a little bit about what those are and specifically, which ones tortoises have that help them survive.

KAREN: When we think about adaptations, it's something about an animal's body or something that animal does that helps it to survive in its specific habitat. For instance, let's take our desert tortoise, as an example. Deserts are pretty harsh environments, especially Mojave and Sonoran. Very, very hot during the day, believe it or not very, very cold or can be very, very cold at night. Very dry, not a lot of food or water around. So they have very specialized things about the structure of their body, as well as their behaviors to help them to best survive in those harsh environments. I mentioned one of the things about a tortoise is the ability to store water. Desert tortoises, at different times, almost half their body weight could be stored water, basically saving that up for a non-rainy day. Another really great adaptation is that shell. So turtles all have shells, most of them are hard shells, many of them can tuck all their soft body parts inside of that shell, keep them safe from animals that might want to eat them. Imagine if you had like a really hard, dog crate, you could sort of hide inside if some big predator was trying to munch down on you, and would stay pretty safe.

ERIC: Such a great adaptation to have that as part of your body that you just have like armor or a place to hide that you just tuck your arms in and you're safe.

KAREN: Yeah, that's what I love about our little box turtles that we have at the museum. They can literally tuck in all four legs, their tail, their head, and they have a flap in the front that is also hardened shell that closes up over their face. So maybe they have a tip of their tail sticking out the back. And that's it. So that's a really extreme adaptation when it comes to the shell, which is I think, super awesome and really fun to see. As long as we're talking about the desert tortoise, specifically, one of their behavioral adaptations is that they spend most of their life in an underground burrow. So even though they have that shell that does still help protect them from predators. But it also helps with those extreme temperature swings in the span of 24 hours in the desert. If you've ever been, say, in your kitchen on a hot summer day, and it's 90 degrees Fahrenheit, you walk from those cellar stairs, maybe it's only 60 degrees in your basement, so it's a lot cooler. Same thing with an underground burrow. So during the hot days, it's going to keep that tortoise at a more comfortable temperature. And then if it gets super cold up on the surface at night, the tortoise is better insulated and keeps their body warm. Now of course, this is super important because as a tortoise, they are ectothermic. That's a characteristic of reptiles. That just means that they don't regulate their own body temperature.

ERIC: So they have this behavioral adaptation of knowing when to go underground, if it's too hot or too cold, and underground is just always more comfortable.

KAREN: Yeah, it's definitely an instinct rather than like a conscious "This is what I'm going to do today". But yeah, it certainly helps them survive in those extreme environments.

ERIC: Now, pretty often when we're talking about tortoises, we get asked about their lifespan because they are famously long-lived. So how long can they live?

KAREN: Well, it really depends on the species that you're talking about. But I've talked a lot about desert tortoises and I'm very well in tune with the desert tortoise we have at the museum. They can live 80 maybe even 100 years. Sometimes it's hard to track them because they will outlive their caretakers or their researchers. Some of the longest-lived tortoises that we have heard of are the giant tortoises like the Galapagos giant tortoise. It lives on the Galapagos Islands, or the Aldabra tortoises that are from the Seychelles atoll, just off the coast of Africa. Now currently living, the oldest tortoise is a tortoise named Jonathan, which I love that it's just sort of a basic human name.

ERIC: I love when animals have people names.

KAREN: Yeah. Jonathan was hatched in 1832. So as of right now, he's at least 188. I don't know exactly if he's had a birthday yet this year. That is the current living, oldest tortoise. Now for Galapagos tortoises, they are also very long-lived. It was just recently that we were still hearing about a tortoise that Charles Darwin himself had collected from the Galapagos and was still living. I think he has since passed away. They average more like 150. But there is an Aldabra tortoise that we think lived upwards of 250 years. Now, again, these are just records. And it's hard to tell exactly how old a turtle or a tortoise is, unless somebody marked down exactly when it hatched out of its egg. The oldest Galapagos tortoise was over 175 years, she died back in 2006. And she's probably one of the ones that Charles Darwin saw. Now, Galapagos tortoises, I'm gonna make one more side note, are really cool in the evolutionary story. So Charles Darwin, evolutionary biologist, he taught us a lot about finches on all the different Galapagos Islands, as well as these tortoises. And they had very specific adaptations for the type of environment on all these different islands. If it was an island that tended to have a little bit higher brush, the tortoises' shell would tilt forward so they can get your head a little bit taller. If it had slightly, maybe more, hardened vegetation, they would have a slightly stronger beak, since turtles don't have teeth, they have a stronger beak. So if you're curious, I highly encourage you to go read up on the Galapagos tortoises because it is fascinating, to kind of see evolution in action.

ERIC: Yeah, those islands, tortoises and finches, and really all those animals teach us so much about how life adapts to different conditions. Because sometimes the conditions are just a little bit different. Sometimes they're really different from island to island, and you can really see how the tortoises or the birds have just changed over time to better fit their environment, to better survive there.

KAREN: And one of the reasons why tortoises are sort of world-spread, I didn't realize they don't live in Australia natively, or no native Australian tortoises. Or in Antarctica, that's because it's really cold. But they are on so many islands across the world. And this is because they're really good at floating. So over the course of you know, hundreds of thousands, millions of years of evolution of life here on earth. Tortoises made their way to different islands because they just can flip over and float on their shell which just boggles my mind, but it's so cool because they get to these different islands and then over time, evolve very specific adaptation for that specific island environment. So it's really cool to study up on. Obviously it's something that I am passionate about.

ERIC: Alright Karen, thank you so much for coming on to the podcast and telling us all about turtles and tortoises.

KAREN: Thanks, Eric, for having me. It was a pleasure to get to talk about one of my favorite groups of animals.

ERIC: You can see our tortoises in person at the Museum of Science by visiting the Live Animal Care Center viewing window or by catching a Live Animal Presentation. Check mos.org for our daily schedule. Until next time, keep asking questions.

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