Behind the Transformation: From Caterpillar to Butterfly

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Speaker 1: Hi, I'm Rick Schwartz and I'm Marco went. 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 iHeartRadio in San Diego Zoo Wildlife Alliance, an international nonprofit conservation organization which oversees the San Diego Zoo and Safari part We're kicking off a new season of Amazing Wildlife and I want to take a moment to introduce my new co host. You may recognize his voice from last season's Axelttle episode, where he helped us learn more about the origin and culture around the word Axelottle. Everyone, meet Marco went, Fellow Wildlife Ambassador of the San Diego Zoo Wildlife Alliance. It's good to have you here, Marco Buenos World, and thanks Rick. I am super pumped to be co hosting Amazing Wildlife with you. I got a feeling we're gonna have a lot of fun. I'm certain we're gonna have a good time too. Now, of course, I know you very well, we have worked together for years. But I'd love for you to take a moment to let our audience know a little more about you. Yeah, of course you know. I grew up at the San Diego Zoo Safari Park. I've been an animal trainer at our beautiful bird shows, moved into the bird department as a wildlife care specialist working with incredible wildlife like a Southern cassuary, and now I get to be a wildlife ambassador, just like you right sharing these wonderful stories. Marco. You mentioned your time as a wildlife care specialists working with birds at the San Diego Zoo Safari Park, and I know that also includes helping with Butterfly Jungle, which just happens to be happening right now at the release of this episode and continues through May fourteenth. Knowing it's happening now and knowing I miss certain aspects of actually working directly with the animals, I was wondering, is there anything you miss about Butterfly Jungle? Oh? You know what, I have to say, My top two favorite memories. One the ecosystem. I love rainforest habits at so going into the puper room and just feel what it's like to be in a rainforest. But my ultimate favorite memory is watching these butterflies when they just came out of that cocoon and they open up those wings as a butterfly and do their first lights into hidden jungle. It's awesome. And know what you mean. I've been there a couple of times for the release. The wildlife care specialist brings the butterflies out into the rainforests basically the open aviary, and it really does bring out that childhood at Yeah, I'm also continually fascinated when I see the butterflies emerging from the chrysalis. I'll agreed, you know, I'm always so curious what's going on in there. I know, right it's crazy. And honestly, when I see that movement right before they're about to emerge, that's super fascinating. Whether they're breaking out of that cocoon or the chrysalis, you know, whatever we want to call it. Right, So this is the thing. Is I wonder too what exactly happens inside the crystalis or cocoon and is it chrysalis or cocoon? Which is its interchangeable either. Well, good news is we do work at the San Diego Zoo Wildlife Lions and we happen to have access to people who can probably answer both these questions for us I am Lynn Phenema, and I am the senior Wildlife care Specialist in Insects at the San Diego Zoo. A cocoon is going to be something that usually a moth me. It's usually made out of silk. Sometimes it's pieces of leaves or whatever from their surroundings. It's something that they make to surround themselves with. A chrysalis is the actual animal itself. So when you're looking at a chrysalis, like say a monarch chrysalis, you're actually looking at the actual animal itself. There's a lot going on inside of there, but that's its actual body, as opposed to cocoon, you're looking at a covering one sec rick. Before we get into what happens in the chrysalis, I was kind of hoping to talk about the caterpillar stage a little bit because at Butterfly Jungle we receive the chrysalis and hang them in the paper room. But I know more happens before it becomes a chrysalis. Ah, good idea. Lynn. Can you start from the beginning of the caterpillar's life for us? Yeah, So, once it hatches from an a, it's just gonna eat and eat any basically That's what capillar's job is, right, is just their whole life is just eating and growing bigger. That's all they do. It's a great life. And as they grow older and they grow bigger, they have to shed their exoskeleton in order to grow. For an insect, their exoskeleton is kind of like clothes we wear almost as we get bigger, our clothes don't get bigger. We have to get new clothes, right as we get bigger and older. Same thing with them. As they grow, they have to shed that exoskeleton and there's a brand new, bigger one underneath, and so they're going to molt. It varies for caterpillars. For something like a monarch, it's usually like four or five times they're going to molten get significantly bigger each time. About four or five molts will do that. Okay, now I have a question. Did she say exoskeleton for a caterpillar, Because when I think of a caterpillar, I think well, squishy, honestly, And when I think of exoskeleton, I think of something hard, like the outer side of a beetle or something like that. Yeah, but I don't think caterpillars have skeletons. Or a bone structure inside. So I guess exoskeleton makes sense. It's not as hard it is like a beetle exoskeleton is still there, but it's thinner and just not as hard as a beetle's exoskeleton, but they still have one. It's going to be most noticeable on what we call the head capsule. The part that is on the head is very noticeable when they mold. So when they shed that you usually just see the head capsule come off and then a little bit of the exoskeleton skin, but it's a very thin and papery, so it's still there, is just thinner. Oh wow, well that makes sense. But if the caterpillar eats and grows and sheds and eats and grows and sheds, how does it know when it's time to become a chrysalist. Does it need to eat a certain amount of food or is it after so many days after hatching from an egg, or is it something else. There's two hormones that are going to control how a caterpillar grows and what it's going to turn into. Actizone and there's juvenile hormone, and those are two really really important things for an insect. To grow and determines what they turn into. So ecdysome, that hormone controls when it's gonna mold. When those levels, those hormone levels start to rise in the caterpillar, that tells it, okay, it's time for me to molt. Right, If there's juvenile hormone, you can guess by the name juvenile. If there's also juvenile hormone present, that's going to tell the caterpillar, I'm gonna mold, and my next mold, I'm still going to be a caterpillar. As the caterpillar naturally gets older, those juvenile hormones start to drop, so you still have the ecdysone, right, that's telling it you need to change. But then when the juvenile hormone levels drop below a certain point, no more juvenile hormone, that tells it now it's time. Now I need to turn into the pupil. And that's just the two main ones. There's a hole you could go down, a whole rabbit hole of all the physiology and the hormones involved in the different secretions and glands. Like I said, it's a lot more complicated. You can go as far into as you want. They've got a different lands. They have a brain that secretes some of these hormones, is you know, not like a mini version of our brain, but they still have one and all these organs that all work together to make this happen. But the ectizone and the juvenile hormone, those are the two big ones that control molting. That is so awesome. I mean, it makes sense now that I hear it. Besides, we know hormones control in different stages of development in mammals, birds, and reptiles, so why not invertebrates too. Seriously, that is so fascinating. I mean, yeah, it makes sense, but wow, I do have a follow up question though, Lynn you mentioned it turns into a pupa. What does that mean? What does a pupa? It's the life stage. So for example, there's the egg that starts off with the larvae. Is the caterpillar like the baby phase, the juvenile phase. The pupa then is that middle transition phase and it pupates. The caterpillar pupates, so the pupa is that niddle stage and then you have the adult butterfly, moth what have you. Ah, that makes sense now, thanks for defining that for us. Okay, Marco. It sounds like we have an understanding of what happens up to the point of the caterpillar becoming a crysalis or the pupa stage. I want to know one more thing before we answer the original question of what happens in the crysalis. Oh man, now I'm curious about what you're curious about. Okay, okay. When the caterpillars hormones say you're done being a caterpillar and now it's time to mold into a crystalis as far as I understand it. Caterpillars will try to find the underside of a branch or the underside of a leaf to hang from. What is it that they used to anchor themselves when they hang like that? It varies depending on what the caterpillar is, what species it is. The one you're probably going to be familiar with is the monarch caterpillars. They actually have hooks at the very end of their body, the very tip of their body, and they're actually going to make a silk pad stick that onto something like the side of a piece of water or whatever, and then they dig their hooks into that little piece of silk, and that's what they're going to hate on too. So it's actually the way the monarchs do it is rather precarious because they're literally hating just by these hooks. They're hanging upside down, you know, in that classic J shape. They're just hating from that one point. So you know, you get a good hard breezer, they shake a little bit and they could fall. There are some other caterpillars that are a little more sturdy. Some of them will actually make like a little hammock for themselves to actually pup it in. Some of them won't even do that. Some of them just go straight to the ground under the ground or just dropping some leaves, which is kind of a lazy way to do it, but you know, I'm not gonna fall, so that's something. So they can use hooks or silk to hate themselves from different things. It's wild to think that a monarch caterpillar has this ability to make silk all along, but it only uses it once in its whole life, and for such an important job too. I know right age where other caterpillars species will like make a silk hammock, or a moth species will spin a cocoon and hide some leaf litter monarch caterpillars are like, I've got this one shot to do this right. My whole future life depends on it. Okay, I think now though, marcolet's try to say we've answered all the questions we've unearthed by trying to answer this one question. Let's finally get to the whole reason we ask Lynn to join us. Oh is it time to ask? I think it is? Okay, Lynn, we want to know, Marco. Wait, what before you ask? I want to know from you, before we had a chance to talk to Lynn, and before you worked a butterfly jungle to Safari Park, what did you think happened inside the crysalis? You know, honestly, I thought it was some combination of like Ninja turtles when their original turtles going to the o, some kind of mutation, or maybe like a werewolf, something along those lines. A werewolf, I know, I know. Okay, Well, yeah, I have to bid. Honestly, I have to say I had no idea until my own curiosity got to better me a couple of years ago and I looked it up. But prior to knowing for sure, I assumed the caterpillar's body just shrunk down to the sides of a butterfly's body, and then it grew long legs and wings, and I mean it made sense of my head anyhow. Okay, Okay, I think it's time to find out the real answer. Yeah, go for it, ask her. Okay, Lynn, Rick and I have shared what we think happens inside the crysalis, but now we need to hear what actually happens when this plant eating larva called the caterpillar makes itself into a crysalis and then comes out this magical flying creature that lives off of the nectar of flowers. This is so cool. It just it really blew my mind when I first learned about this. So what actually is happening is it's not like we said, you know, it's not just growing wings or anything like that. The whole animal itself, that caterpillar inside of that crystallis actually breaks down into essentially caterpillar soup. It turns into goo. Essentially. There are enzymes that go to work and actually break down and digest all of the caterpillar into different parts. Now there's a few parts like the breathing tubes and things that will remain the same so that the animal can keep on living. But all the different parts that you saw before are actually going to break down and just turn into soup. If you were to break open a chrysalis early, you would just get goop. But that is the animal. So how does it go from that to a butterfly? Incredible? Right, There's clumps of cells inside of the caterpillar that have always been there. They're called imaginal discs. The caterpillar is actually born with this, even when it's just an egg, it always had these imaginal discs inside of itself and they remain dormant until the time comes. So when it goes into the pupy and the digestive enzymes have breaken it down, then those imaginal discs start up. They start multiplying and growing like crazy. And it's those imaginal discs that are going to multiply and turn that soup into all the new different body parts that are going to make up the butter fly. There's an imaginal discs for legs, there's a group for wings, a group for the head, that sort of thing. So those clumps of cells that were dormant inside this animal the whole time are finally going to turn on and turn that whole mess that was a caterpillar into something completely new? WHOA that is so rad Seriously, everything turns to caterpillar soup. Can you imagine what once was a foot cell and what once was a mouth cell, or all just floating around, bumping into each other, just waiting to be reconstructed into something new. I mean, essentially everything that was once a caterpillar gets broken down and recycled into a butterfly. But that makes me wonder if mostly everything gets turned into caterpillar soup and then rebuilt as a butterfly, are they just coming out as a butterfly like a whole new being, like this is day one for them in their mind, or do they have any memory or knowledge of life as a caterpillar. There is one study where they actually taught caterpillars to avoid certain smells. So when the caterpillar these certain smells were exposed to it, they learned to move away from it. They were taught not to like it. You take that caterpillar turns into a butterfly, That butterfly still flies away from that smell that it didn't like when it was a caterpillar. So there's some part that they do still remember from being a caterpillar. They do learn, and there's something about them that still stays. I don't know how that happens, honestly, now they can retain that memory, but they do, and they remember that bad smell that they don't like, and they try to get away from it. All right, mind blowing. I have so many more questions about what a butterfly remembers and doesn't remember, about the process of being a caterpillar and then becoming a crysalis filled with caterpillar soup and then hatching out. I mean, for instance, have you ever suddenly had a craving for some comfort food from your childhood and they just sat down and enjoyed it. I mean, does a butterfly I ever get a craving to have some leaves that used to munch on when it was a caterpillar? I don't know, but I want to know. Yeah, I gotta admit I was a fan before, but I'm even more into butterflies now. I mean I knew some of this already, but the memory, the imaginal cells, kid bothery, I am right there with you, Marco. It is so cool and as amazing as it is. I think my favorite part was hearing how passionate and excited Lynd was to share what she knows about the animals she cares for. Honestly, I'm kind of curious, Lynn, where does this love and passion for invertebrates come from? Oh my gosh. I mean, you know, like a lot of people go through that bug phase when they're a little kid, where like you're coming home with caterpillars in your pockets and that sort of thing. Like I never grew out of that. I still love exploring and finding bugs and just looking at them. I think they are the closest things that we can get to magical creatures out there. Just from like I was telling you, with just how complicated pupating is and things like that. I just I think they're so fascinating and I just never have and never will grow out of that mystified phase of looking at these guys. Thank you, Lynn for completely and forever changing how we look at the magic that is a butterfly. Yes, thank you Lynn, and everyone in the entomology department at the San Diego Zoo, and of course everyone in the bird department at the Safari Park who are all working so hard to make Butterfly Jungle such a magical experience. Oh and I also want to say thank you to the horticulture department too, Marco, because they bring in an awful lot of flowering plants for all of those butterflies to enjoy. And I think that kind of falls under the radar sometimes because we're so distracted by the butterflies. And that leads me to my next thought. Really, it's fair to remind everyone that butterflies and many other invertebrates. Yes, they are beautiful and borderline magical, but they play an important role in the environment, in the ecosystems that we all rely on. Pollination powers of the butterfly or the ability to break down natural materials like maybe a larvae or caterpillar could all very important for the plants and beneficial to all of us. All right, so what do you think, Marco? Was this a good way to kick off season two? Oh? Absolutely? I mean we got to talk about butterflies, Safari Park, San Diego Zoo one team win dreams. I thought it was perfect. And also caterpillar soup dint forday about the soup. Thanks for listening to everyone, We help you learn something new about caterpillars and butterflies. Be sure to subscribe and tune into our next episode, in which we let our curiosity lead us to some surprising information about one of Africa's big cats. Marco Went and I'm Rich Schwartz. Thanks for listening. For more information about the San Diego Zoo and San Diego Zoo Safari Park, go to SVZWA dot org. Amazing Wildlife is a production of iHeartRadio. Our supervising producer is Nikkia Swinton and our sound designer and editor is Sierra Spreen. For more shows from iHeartRadio, check out the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.