Galapagos Tortoise: The Zoo’s Oldest Friend!

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Speaker 1: Hi, I'm Rich Schwartz. Hi, I'm aperni Mone Welcome to Amazing Wildlife, where we explore unique stories of wildlife from around the world and uncover fascinating animal facts. This podcast is a production of I Heart Radio and San Diego Zoo Wildlife Alliance, in international nonprofit conservation organization behind the San Diego Zoo and Safari Park. This next species is affectionately known as our oldest friend at the San Diego Zoo. We're learning more about a giant reptile that has been fascinating people for more than a century. In fact, Charles Darwin documented his first encounter with the glopicals tortoise during his historic voyage from one to eighteen thirty six. The Galopicos tortoise is credited with possibly helping to inspire Darwin's theory of natural selection. Rick, what's the connection between the gallop Coos tortoise and his famous theory? No, it's it's pretty cool. But honestly, before we jump into the connection between the Glopicus tortoise and Darwin's work and the theory of natural selection, I want to make sure we are all on the same page when it comes to the definition of a scientific theory. The scientific method that results in a scientific theory is a little different than how the word theory is commonly used in our general language. So most people use the word theory to mean an idea, speculation, or hunch for example. But when the scientific method is used, a scientific theory creates a structured explanation based on our best available knowledge and facts. And just to remind everybody, the scientific method is based on five steps. It's observation, hypothesis, experiment, analysis, and then conclusion. Now that said, Charles Darwin's work is understanding how the species of the Globus islands seemed related to the ones found on the mainland, but that also includes that many physical variations seem to be unique to each island with these species. All of this lead him to a scientific theory of natural selection. Essentially, he found that variations natural only occur within a species, and in those variations, certain ones allow for better survival in specific environments. Therefore, those with variations that allowed for better survival, well, they would live longer and produce more offspring passing on the genes of that variation. But those with variations that don't allow for survival well, they wouldn't live as long and reproduce, therefore not pass that on, creating that change in the species. As the process continues across several generations, well, the species starts to change and evolve. Rick what was it about the Galopicos tortoise that supported this theory? Along with observation of many species, one thing that definitely caught his eye with regards to the giant tortoise epity was that each of the thirteen islands, the larger islands of the Glopicus Archipelago, had a slightly different form to the shells, size, and shape of these now famous giant tortoises. He observed that each was uniquely suited for survival on that particular islands environment. So, for example, dome shells were found on tortoises living in high lands with lush natural past years of grass and low growing plants, whereas saddleback shells shells shaped with sort of a tall arch in the front like a saddle gave the tortoise on other islands the ability to reach their heads up high, allowing them to stretch their neck to eat from bushes and cactuses. Because their environment was sparse with vegetation that has found sort of higher off the ground than the ones that had pastures. Also, he observed that on islands with that sparse vegetation, the tortoises have longer legs to climb a little and to reach for food growing higher. Interestingly enough, these tortoises tend to also be a little bit smaller, possibly to help them travel through their harsher environment. I always find discussions about natra selection fascinating, so that was very fascinating. So how many different species of glocos tortoises are there? This has been a very interesting process as we've learned more across the years. Currently, e beaning, there are fifteen subspecies of the giant tortoise uniquely suited for survival on these particular island habitats. However, right now, four of those fifteen are considered extinct. And I say as of right now because one thing I have learned. As science continues to evolve and change and we continue to better understand the world around us, we learn more. So who knows what discoveries we might make in the near future about these amazing tortoises. We can hope. So can we talk now about the San Diego Zoo's long history with the glopicals tortoise. The San Diego Zoo is celebrating it's one hundred and six anniversary this year. And while you've been with the zoo an impressive amount of time, there's some Galapagos tortoises that have you been, Yes, I said, hope, so epeny, my goodness, I'm not that old. Yes, I have been with the zoo for most of my long career, but my time at the San Diego Zoo is nowhere near some of our Glopicos tortoises. In fact, some of the zoo's oldest residents are the Globos tortoises. Several have been with us since the late nineteen twenties and early nineteen thirties, making them the oldest residents of the zoo. And given that most of them came to us at a pre a decent size, it is assumed that they were already twenty years old or older when they arrived at the San Diego Zoo. So doing the math on that, you soon realize they're well over a hundred years old. Wow, So how long can glopicals tortoises live? H This is always an interesting question ebany because they live so long. Many individual Gallopicas tortoises have been around longer than we have had appropriate record keeping, so for most of them we are only able to estimate their age. We don't actually know for sure when they hatched. With that in mind, I do want to share there was a female Gallopicus tortoise at another zoo that we know lived to be over a hundred and seventy years old. Rick have glopicals tortoises like stumbled upon the Fountain of youth? What do scientists attribute their long lives to. Yeah, exactly. A there's a fountain in the middle of Glopicus islands that just pours out this youthful water for them. So that's it. That's a secret right there. Uh No, it really At least part of the reason that we know is the aw metabolism. It's believed this plays a big role in their longevity. So, in all fairness, the connection between metabolism and longevity isn't completely understood, but it is believed that the faster the metabolism, the more free radicals or unstable molecules that can damage cells increase in the body. So when we look at it, from the other side, the slower metabolism means less damage to the cells over the long run, which would then allow for a longer life and also worth mentioning here. It was further understood after the famous tortoise Lonesome George passed away. Now Lonesome George, for those who don't know, was believed basically to be the very last of his kind for several decades, and they tried to get him to breed with a female or maybe create a hybrid version of his kind, but he never did. And so when he passed away, they did do a genetic analysis of his DNA and they did quite a few different things that they were looking at looking for, and essentially they found that Gallopicus tortoises possessed several gene variants that are linked to DNA hair immune response and immune health and cancer suppression. So these gene variants are not present in short lived vertebrates. It's very interesting for them to find this in the Glopicus tortoises. So I was choking, but they're may be locked in their genes. There is some information about long life, yeah, exactly. Essentially, there may be a fountain of views, but there may be some DNA of youth, So Rick, could the galopicals tortoises diet possibly hold some of the secret to their long lives as well? Well, it's possible they are herbivores of any meaning of course that they eat plants, and like we've mentioned, they have a slow metabolism, so they are either eating or sleeping. Galopicas tortoises will sleep or rest in average of sixteen hours a day. The rest of their time, depending upon which island they are on, will be spent grazing on grasses and low growing plants, or enjoying taller plants and cactus pads. And of course they will drink and bathe and water if and when it's available. But get this, if needed, they can survive up to a year without food or water. That's surprising to me just because of their large size, But I think we've learned through this conversations that there's not necessarily a direct correlation between the animals large size and what they eat. Um as far as right being herbivores. So the galopicals tortoise is known for its large size. Just how big can they get? They can get pretty big ebony the adult size will vary depending upon the subspecies, but in general, males are up to six feet long from head to tail and yes they do have a tail, and about four to five ft across on the curvature of their shell. We also see a size difference in the weight between the males and females too, with males weighing up to five hundred seventy pounds and females up to three hundred pounds. And I must admit that's pretty impressive because when they hatch out of their egg ebony they only weigh about two to three ounces, so that's less than a fourth of a pound. Wow, that sounds impressive. So how long Rick, does it take for the Gallapicos tortoises to reach their full size? Well, they usually reach sexual maturity around twenty years of age, and the majority of the growth does happen in those first years, although growth does slow after that, they don't really stop growing until closer to forty years of age. Rick. Today, there's an estimated twenty thousand to twenty five thousand tortoises living on the Gallopicals islands and unfortunately there's been a population decline. What are some of the causes yes ebony. Unfortunately, the gallopus tortoise have a long history of being hunted for food by sailors and whalers that traveled through the oceans of that area from the seventeenth through nineteenth centuries. At the time, of course, they seems so abundant, so no one thought anything of it. And again, like we mentioned, tortoises will live quite a long time without food and water, so sailors would capture them and bring them on board, and that way they'd have fresh food out at sea as well. Unfortunately, these same ocean traveling humans would also drop off live goats and pigs on these islands as well. Now, these animals would thrive on the islands, reproducing easily with no real predators to worry about. The sailors knew then that they could stop off at these islands later and hunt these now feral pigs and goats for fresh food during their long journeys at sea. Unfortunately, these goats and pigs eat much of the same food that the gloppas tortoises eat, and they also damaged or destroyed nesting sites as well. Additionally, humans coming and going from these islands from ship to shore like that, and while they inadvertent, we also introduced rats to the islands as well. Although rats don't pose much of a risk to adult tortoises, they love rating nests and eating the eggs later than when humans started populating the islands well, they also brought with some cattle, donkeys, dogs, and cats, all of which either damaged nesting sites, injury young tortoises, or in some cases even kill them. Now, any one of these one things would be challenging for a species like the Gloppicus tortoise that evolved on these islands away from any of these challenges, and if, well, when you think about it, you stack all these up, it becomes too much. The result is a drop in the population, and sadly, there are some types of Gloupas tortoises that went extinct many years ago. Thankfully, the Gloppacus National Park and Gallopacus Conservancy I've been making big strides in tortoise conservation, from habitat restoration and protective laws to breeding programs and headstart programs with young tortoises. Numbers are now stabilizing and even growing for many of the subspecies of Gloupicus tortoises. Rick they really are doing some great work I understand on the Galopicals Islands. How has the San Diego Zoo Wilife Alliance played a role in helping with galapicals tortoise populations in conservation yes, ebony, aside from caring from our own population of Glopicus tortoises at the San Diego Zoo for almost a century. Back in nineteen sixty nine, the San Diego Zoo Wildlife Alliance partnered with the Charles Darwin Station on the Galopicus Islands to help fund a new tortoise rearing facility. Historically, the San Diego Zoo Wildlife Alliance has also helped with managing propagation and reintroduction programs. And I can tell you from when I was there a few years ago, that reproduction program and the facilities. It's truly amazing how much work they're really putting into this. And as a result of this partnership, a Galopicals tortoise that one lived at the San Diego Zoo played a significant role in the animals population growth. Rick who is Super Diego, Yes seventy my favorite. The very famous Super Diego Well Diego story actually starts back in the nineteen sixties, when conservation action was really getting going for the Gloppicus tortoises, it was found that the subspecies of Glopas tortoise from the island of Espaniola was critically endangered, with just two males and twelve females left, so a search for any remaining Espaniola tortoises was on. With several populations of tortoises sent to zoos around the world in the nineteen thirties, there was hope that more Espaniola tortoises would be located, and sure enough, Diego at the San Diego Zoo happened to be from the island of Espaniola. He was sent back to the Gloppicus islands to be part of their breeding program in nineteen seventy seven, and well, let's just say Diego took his job of saving his kind very seriously and earned himself the name Super Diego because he fathered about one thousand, seven and hundred children in his time at the breeding facility. And thanks to the efforts of Diego, I mean Super Diego, many Espaniola tortoises have been returned to their home island and after doing so well at helping save his own kind. Diego has recently retired from the breeding program and has returned to the island of Espanola as well. Wow Super Diego. Coming up, we'll find out what an amazing wildlife young listener wants to know about the Galapagos tortoise. But first this now it's time for the San Diego Zoom Minute, an opportunity for you to learn what's new at the Zoo. Earlier this year, a three month old giraffe calf at the San Diego Zoo Safari Park has received a new lease on life thanks to the swift action of our teams. The female youngster, named Suttuni which means in the forest and Swahili, received a pair of specialized giraft pattern orthotic braces that attached to her front legs to help correct her hyper extension. This disorder, also known as tendent laxity, had caused the giraffe front legs to bend in properly and made it difficult for her to stand or walk. Wildlife care specialists said Stuny's chances of survival would have been very low without the treatment provided by the San Diego Zoo Wildlife Alliance team in collaboration with orthosist at Hanger Clinic. Did you know? In twelve renowned geneticist Dr Oliver Ryder was invited to an international workshop on the Galapagos Islands to plan the next ten years of Galapagos tortoise conservation efforts. Doctor Writer is the Kleeberg Endowed Director of Conservation Genetics at San Diego Zoo while left Alliance, as well as a creative problem solver with a deep capacity to understand the big conservation picture. The workshop used the expertise of people around the world in many different fields, including ecology, biology, horticulture, herpetology, physiology, genetics, and wildlife disease among there's Today, we've talked about the gallopicals tortoise and we have a question from one of our young listeners. Shall be tortoises good swimming? Oh Shelby, That is a good question. Even scientists wondered about this the first time they came across the giant tortoises hundreds of years ago. And I think when we look at these giant lumbering reptiles that kind of looked like rocks with legs, it's pretty easy to assume that they would sink in deep water. We'll get this in naturalist William B. Bait decided to see for himself and placed a gallopacus tortoise in the ocean, and thankfully, what do you know? The tortoise proved to be able to swim and extending its neck above the water and paddling, albeit slowly, and even able to steer itself towards land. They may not be as good at swimming as their relatives to sea turtle, but they can manage pretty well for themselves given their size. That said, gloupas tortoises are rarely seen heading out to the ocean on their own or swimming in deep waters. Have tea well shelby. We do know they are able to take big bites of flowers, fruits, and even tough cactus paddles, So you would think they would have teeth to bite through those, but they don't. They do have bony outer edges along their mouth and a very dense and sharp carratin covering over them. Now, keraton is the same protein that makes up your fingernails and the beaks of birds. In fact, some people will even refer to the edge of a tortoise's mouth as its beak, so no teeth but still a very effective and sharp bite or together. Oh well, Shelby, the answer to that is kind of yes and kind of no. Let me explain the dome to show. Gallops tortoises that live in the lusher grassy areas tend to share space and live in close proximity to each other and crossing paths and sharing feeding spaces together, but there's no real social dynamic like you'd see maybe in a herd of elephants or a pride of lions. And then the other side of that, well, the saddle back to Gylopicus tortoises that live in the drier areas tend to be solitary and keep to themselves most of the time. So yeah, kind of yes and kind of no on living together and ah yes, Shelby, the circle of life, well, believe it or not. There are no natural predators of the adult Gallopicus tortoises. In fact, before humans introduced other predatory species to the Glopicus islands, the only natural predator to the Glopicus tortoise was it a Glopicus hawk. Now, this bird of prey will sometimes eat the eggs or hunt the hatchlings of the Gloupicus tortoise, but the hawk is too small to hunt the tortoises once they start to grow a little larger, and definitely can't hunt the adults. Shelby, I want to thank you for taking the time to send in those questions. I really appreciate it. One of the best ways we can learn more about wildlife is to always be curious and ask questions like these, And if any other young listeners have questions about wildlife, please send us an audio file of you asking your questions to wildlife at my heart media dot com. Then keep listening to see if we answer your questions on an upcoming episode. Yes, thanks to Shelby for those thoughtful questions, and thank you for listening. We hope you learned a lot about the Galapagos tortoise. Be sure to subscribe and tune into next week's episode, in which we bring a story of an animal that's gray, but for some reason we call them white. I'm Epenny Money and I'm Rich Schwartz. Thanks for listening. If you would like to find out more about San Diego Zoo Wildlack Alliance, please visit sdz w A dot org. Amazing Wildlife is a production of My Heart Radio. Our producer is Nikia Swinton and our executive producer is Marcy to Peanut. Our audio engineer and editor is Sierra Spreen. For more shows from my Heart Radio, check out the I Heart Radio app, Apple podcast, or wherever you listen to your favorite shows m HM.