Speaker 1: Hey, welcome to Stuff to Blow Your Mind. My name
Speaker 1: is Robert.
Speaker 2: Lamb and I am Joe McCormick, and we are out
Speaker 2: this week, so we're bringing you an episode from the vault.
Speaker 2: Today's episode originally aired on December eighth, twenty twenty two,
Speaker 2: and it is part one of our series on the
Speaker 2: reptiles of the Galapagos Islands.
Speaker 1: All right, let's dive right in.
Speaker 3: Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Speaker 1: Hey, welcome to Stuff to Blow Your Mind. My name
Speaker 1: is Robert Lamb.
Speaker 2: And I'm Joe McCormick, and today we're beginning a series
Speaker 2: of episodes on the reptiles of the Galapagos Islands. And Rob,
Speaker 2: this is not a topic we just landed on randomly.
Speaker 2: This is related to your recent travels, right.
Speaker 1: Yeah. I had the great pleasure in the fortune to
Speaker 1: visit some of the islands of the Galapagos Archipella go
Speaker 1: back in October. It was a fantastic family trip that
Speaker 1: we'd been planning for a long time, that we meant
Speaker 1: to do before the pandemic and then obviously we had
Speaker 1: to reschedule. But yeah, this is this was one of
Speaker 1: the top trips I've ever had the privilege to make.
Speaker 1: And now certainly I was visiting as a tourist. But
Speaker 1: one of the things about the Galapagos Islands that I
Speaker 1: love is so much of the tourism there is about
Speaker 1: the natural beauty of the place. It's about the environments,
Speaker 1: it's about the animals. And so if you're going all
Speaker 1: the way to the Galapagos Islands, you probably want to
Speaker 1: see some reptiles, you probably want to see some birds,
Speaker 1: et cetera. And they really facilitate that. The local guides
Speaker 1: are all terrific, all the ones that I interacted with
Speaker 1: very knowledgeable of everything going on there. And yeah, it
Speaker 1: was a trip just unlike any other, especially when when
Speaker 1: observing these various creatures, because it was kind of like
Speaker 1: being a Disney princess, like being in a Disney like
Speaker 1: a Disney princess scene in a movie, except instead of
Speaker 1: the princess being surrounded by cute squirrels, bunnies and birds
Speaker 1: that are singing, you're just constantly surrounded by this wonderfully
Speaker 1: bizarre cast of reptiles and elaborate birds, sea lions, etc.
Speaker 1: And it's unlike too, I have to say, it's unlike
Speaker 1: the vibe that I've encountered in places like the Grand Canyon,
Speaker 1: where there'll be wild animals there that are protected and
Speaker 1: so accustomed to humans that the humans can get like
Speaker 1: unnaturally and alarmingly close to those animals. There's a proximity
Speaker 1: to the animals on the Galapagos Islands that feels less
Speaker 1: artificial but also equally magical, if that makes sense. Again,
Speaker 1: not to say that you should attempt to touch any
Speaker 1: of the animals there, or or or infringe upon their
Speaker 1: personal space in any way, but there's this, Yeah, there's
Speaker 1: this feeling of proximity to nature that makes you feel
Speaker 1: like you are David Attenborough in a David Attenborough documentary,
Speaker 1: you know, creeping up for a close look at this
Speaker 1: animal or another.
Speaker 2: And maybe you are the camera lens. And I wonder
Speaker 2: if the difference with the Grand Canyon thing would be
Speaker 2: the difference between animals that are unfortunately habituated to human
Speaker 2: presence in all the wrong ways, like expecting you to
Speaker 2: have food, the calorie rich food sources and stuff, so
Speaker 2: they'll come up to you looking for that, versus a
Speaker 2: place where animals don't seem to flee from humans because
Speaker 2: they come from many generations of animals without natural land predators.
Speaker 1: Yeah, yeah, and I believe that is the case with
Speaker 1: the Glapicos. So let's let's introduce everybody to the Glapico silence.
Speaker 1: If you're not familiar with the Glapagos Archipelago, it is
Speaker 1: a chain of islands in the eastern Pacific Ocean, roughly
Speaker 1: nine hundred and sixty six kilometers or six hundred miles
Speaker 1: off the coast of Ecuador. It consists of thirteen major
Speaker 1: islands a few smaller islands, and these were all formed
Speaker 1: by repeated volcanic eruptions. The process here is similar to
Speaker 1: that which produced the Hawaiian Islands, which we've discussed in
Speaker 1: the show before. So they're not formed all at once,
Speaker 1: but in a chain due to underlying volcanic activity berthing
Speaker 1: mountains and islands out of the ocean floor. So, as
Speaker 1: with the Hawaiian Islands, the islands here in the Galapagos
Speaker 1: are geologically quite young and their individual ages vary. Now, Joe,
Speaker 1: I'm not sure what age ranges you've come across for
Speaker 1: them when we get into the geologic age of the
Speaker 1: Galapagos Islands, but I've seen it vary a bit. The
Speaker 1: Galapagos Conservatory says, quote, probably no more than five million
Speaker 1: years with the younger volcanically active westernmost islands perhaps as
Speaker 1: young as hundreds of thous sin of years old.
Speaker 2: But the idea that none of the islands there today
Speaker 2: are are more than five million years.
Speaker 1: Old according to some of the dates that I was
Speaker 1: looking at these sighted dates, but just sort of casting
Speaker 1: a wide net, I did see some other dates out there,
Speaker 1: so you know, I can only speak to the ones
Speaker 1: I'm citing here.
Speaker 2: Well, estimates vary a bit, but it also depends on
Speaker 2: what you're counting as the Galapagos Islands. For example, I
Speaker 2: was reading a passage in a book Galapagos a Natural History,
Speaker 2: second edition by John Creecher and Kevin Laughlin from Princeton
Speaker 2: University Press. That new edition is just out this year,
Speaker 2: in twenty twenty two, and there is a section in
Speaker 2: this book where the authors put forward the possibility that
Speaker 2: some species on the islands, including the famous giant tortoises,
Speaker 2: may have inhabited the Galapagos since before any of the
Speaker 2: Galapagos Islands existed. Now, how could that be possible? Well,
Speaker 2: here's what they argue. If you look around the area
Speaker 2: of the archipelago, especially east of the existing islands, you
Speaker 2: will see what are called sea mounts, which are submerged islands.
Speaker 2: They are areas where the ocean floor rises up to
Speaker 2: form a mountain, but that mountain does not break through
Speaker 2: the surface of the water. So it's not an island
Speaker 2: from our perspective, but it's sort of like an island
Speaker 2: just beneath the water. Now, what are these seamounts in
Speaker 2: the eastern part of the archipelago. Well, Creature and Laughlin
Speaker 2: write that they are quote eroded volcanic islands, and that
Speaker 2: they are possibly the original ancestral Galapagos. So they were
Speaker 2: once perhaps islands that did break above the surface, but
Speaker 2: have eroded over time. And the authors here cite a
Speaker 2: group of oceanographers and geologists led by a researcher named D. M. Christie,
Speaker 2: who put together some dates for these seamounts and said
Speaker 2: that the dates range from between five to not nine
Speaker 2: million years, which is older than any of the existing
Speaker 2: Galapagos islands today. So to read from this passage quote,
Speaker 2: as Christie's team pointed out, if the original Galapagos islands
Speaker 2: formed as much as nine million years ago, there has
Speaker 2: been more time for colonization and subsequent evolution than once believed.
Speaker 2: This is colonization by non human animals. There may well
Speaker 2: have been tortoises on the islands for longer than any
Speaker 2: of the present day islands have been in existence. Given regular,
Speaker 2: albeit accidental dispersal, new islands forming over the Hotspot will
Speaker 2: be colonized even as old islands erode and disappear beneath
Speaker 2: the sea from whence they came. So normally you're talking
Speaker 2: about an island group, you would imagine that, okay, well,
Speaker 2: the earliest it could have been colonized by animal species
Speaker 2: is whenever the islands we have today began. But in
Speaker 2: the case of the Galapagos, a lot of the evidence
Speaker 2: of the earliest colonization by animals could be under the waves.
Speaker 2: It could be lost because those islands aren't there anymore.
Speaker 1: The lost animal kingdoms of the Galapgos potentially. Now, when
Speaker 1: we're talking about the modern day Galapagos islands, some of
Speaker 1: the main ones, just to mention them real quick, you
Speaker 1: have Isabella, which is the largest. You have Santiago Fernandina,
Speaker 1: you have Santa Cruz, you have San Cristobol. I only
Speaker 1: really visited Santa Cruz and San Cristobal and a couple
Speaker 1: of smaller unoccupied by humans islands that were quite fascinating.
Speaker 1: And one of the things about these islands, and you've
Speaker 1: often counted this with volcanic island formations, is that they're
Speaker 1: defined by steep out elevation changes and the resulting islands
Speaker 1: that contain multiple micro climates due to this, So a
Speaker 1: visit to even a single Galapagos island is an encounter
Speaker 1: with multiple and varied ecosystems.
Speaker 2: Right, So you'll get different climates and different vegetation and
Speaker 2: so forth at different elevations on the island. So and
Speaker 2: that type of like what vegetation is flourishing therefore might
Speaker 2: vary with the seasons. So when the rainy season comes,
Speaker 2: you might get more blossoming of vegetation in the lower areas,
Speaker 2: but then other times animals might find the most fruitful
Speaker 2: foraging up in the highlands.
Speaker 1: Yeah. Yeah, So it's any one of these islands, you'll
Speaker 1: have you have sort of desert environments, you'll have highland
Speaker 1: lush environments, you'll have coastal environments, and these are these
Speaker 1: are This is one of the reasons that these islands
Speaker 1: are often singled out historically, but even in modern research
Speaker 1: is kind of a laboratory of evolution. Now, I'm going
Speaker 1: to keep referring back to Hawaii a little bit for
Speaker 1: a while because I think it's a nice sort of
Speaker 1: touchdown to compare, especially since we've talked about those islands
Speaker 1: on the show before as well. So when it comes
Speaker 1: to Hawaii, as we've discussed before, you have such geographic
Speaker 1: isolation that with those islands, so that there are actually
Speaker 1: no native land reptiles or amphibians there. So anything in
Speaker 1: the categorization of reptil or amphibian that you find there
Speaker 1: were introduced by subsequent human arrivals by boat or ultimately air.
Speaker 1: That's the Hawaiian Islands. We don't have the same situation
Speaker 1: with the glabgos islence for a few different reasons. So
Speaker 1: as far as humans go, first, human contact with Galapagos
Speaker 1: comes a bit later. We're talking about fifteen thirty five
Speaker 1: versus Hawaii's between one twenty four CE and eleven twenty CE. Also,
Speaker 1: Hawaii is a greater distance from the nearest continental land mass.
Speaker 1: And I should note that I think I've pointed this
Speaker 1: Alma show before, but there is some dispute on whether
Speaker 1: the Inca ever reached the island, but we can be
Speaker 1: certain that Europeans reached the island in fifteen thirty five.
Speaker 2: Yeah, exactly three hundred years before Darwin did.
Speaker 1: By the way, Yeah yeah.
Speaker 2: So the story of the first confirmed human landing on
Speaker 2: the Galapagos is very interesting, so I wanted to tell
Speaker 2: it here. There was this Spanish clergyman named Tomas de
Speaker 2: Berlonga who was a bishop eventually served as the bishop
Speaker 2: of the Colony of Panama, and I've read it alleged
Speaker 2: in several sources that Berloga was responsible for introducing bananas
Speaker 2: or plantains to the New World, which is weird because
Speaker 2: despite how much we associate bananas with the Caribbean and
Speaker 2: South America, they are originally native to Southeast Asia. So
Speaker 2: it is alleged that this guy's responsible for bringing bananas over,
Speaker 2: but I'm not sure what the original source of this
Speaker 2: claim is. Anyway, in fifteen thirty five, Berloga was traveling
Speaker 2: by ship from Panama to Peru to help sort out
Speaker 2: some kind of horrible sounding squabble between the conquistador Francisco
Speaker 2: Pizarro and another conquistador over land and spoils after their
Speaker 2: conquest of the Inca Empire, so Burlonga's on the way
Speaker 2: down to try to help sort this out. But as
Speaker 2: his ship is traveling south along the coast during the
Speaker 2: first half of the journey, it is suddenly struck by
Speaker 2: a dead calm that prevents the ship from sailing further,
Speaker 2: and then it gets dragged far off course out to
Speaker 2: sea by strong ocean currents, and just when supplies, including
Speaker 2: fresh water, are about to run out, the crew sits land.
Speaker 2: Their prayers have been answered, but like so many early visitors,
Speaker 2: these Spaniards are almost instantly dejected by what they find.
Speaker 2: The first island where they land is found to have
Speaker 2: not a single drop of fresh water, and there's also
Speaker 2: no pasture where their horses can graze, just a bunch
Speaker 2: of giant tortoises and weird iguanas. But there were other
Speaker 2: islands nearby, so the crew tried to sail to another
Speaker 2: one to continue the search for water. Unfortunately, on the
Speaker 2: way they were once again becalmed and could not sail
Speaker 2: for several days, while just languishing there on the ship,
Speaker 2: nearly dying of thirst. Finally the wind picked up again
Speaker 2: and they were able to reach a second island, where
Speaker 2: once again they found no fresh water. They tried to
Speaker 2: dig a well, but when they struck groundwater, they found
Speaker 2: it to be as bitter as the sea. And here
Speaker 2: I want to read from the retelling of this story
Speaker 2: by the famous naturalist William Biebe in his book Galapagos
Speaker 2: World's End, published in nineteen twenty four, BB writes, in
Speaker 2: their extremity, they had recourse to a plant which has
Speaker 2: saved many a thirsty man and animal, And by chewing
Speaker 2: the fruit and juicy stalks of the cactus they kept
Speaker 2: themselves alive.
Speaker 1: They took a page from the tortoise playbook. There.
Speaker 2: Yeah, not all withstood these privations. One man and two
Speaker 2: horses died of thirst, and so the first grave on
Speaker 2: the Galapagos was dug. Sunday came and the bishop celebrated
Speaker 2: high Mass on those desolate shores, where as he said, quote,
Speaker 2: it looked as though God had caused it to rain
Speaker 2: stone ones, brutal doom metal bishop. And then BB goes
Speaker 2: on sea. Lions slipped through the creaming surf and looked
Speaker 2: curiously at the little group of strange beings, and long
Speaker 2: winged seabirds poised and swooped above the cross and the
Speaker 2: Spanish flag planted side by side among the cactus and
Speaker 2: thorny scrub. So I think BB's taken a little liberty
Speaker 2: with the storytelling there, but all plausible, you know, given
Speaker 2: the local flora and fauna.
Speaker 1: Yeah, desolate beaches, weird sea lions hanging about. Well, I
Speaker 1: guess the sea lions are generally described you as weird.
Speaker 1: They would have certainly been exposed to sea lions already,
Speaker 1: but in my books, sea lions are inherently strange but
Speaker 1: also very amusing to watch.
Speaker 2: They're just playfully rolling about while these people have church,
Speaker 2: dying of thirst. So finally, after the worship service, the
Speaker 2: Spaniards did find some small amount of fresh water. I've
Speaker 2: seen what they found, alternately described as spring water and
Speaker 2: as little pools collected in cup shaped depressions in the rocks.
Speaker 2: And using this water, either the spring water or the
Speaker 2: rock pools, they filled up their containers and they departed
Speaker 2: again for the coast of Peru. Now, Burlanga made a
Speaker 2: number of observations while on the island, writing, according to
Speaker 2: an eighteen eighty four translation of his letters, that the
Speaker 2: animals of the Galapagos were quote so silly that they
Speaker 2: did not know how to flee, and that as a result,
Speaker 2: wild animals were easily caught in the hand.
Speaker 1: Well, that does match up, I think with the reality
Speaker 1: of visiting the Glabgos Islands even today. Not that you
Speaker 1: should be chasing any of the animals and certainly not
Speaker 1: catching them in the hand. But yeah, there is this,
Speaker 1: like I said, there's this sense that they don't necessarily
Speaker 1: understand what we are and they're not threatened by us
Speaker 1: unless we get too close, and then a lot of
Speaker 1: these animals will let you know. So, yeah, don't get
Speaker 1: too close to the sea lions wherever you find your
Speaker 1: sea lions. Don't get too close to the tortoises of
Speaker 1: the Iguanas.
Speaker 2: Now, Rob, you mentioned that the tourism at the Galapagos
Speaker 2: today is almost entirely centered around the island's natural beauty
Speaker 2: and biological and ecological significance. You know, this is a
Speaker 2: place where you go to see the natural landscape and
Speaker 2: the flora and fauna. You're not going there to see
Speaker 2: to go to six Flags Galapagos.
Speaker 1: Right right, Yeah, Yeah, I mainly mean, yeah, you're not
Speaker 1: going to find that. You're not going to find I
Speaker 1: didn't really see much in the way of like a
Speaker 1: party boat kind of culture that you find in a
Speaker 1: lot of locations. It's you know that there is there
Speaker 1: is culture there. There's some great restaurants, there's there's great
Speaker 1: local culture. And the people who live there were on
Speaker 1: the whole very friendly and and I loved interacting with
Speaker 1: them quite a bit. But yeah, it's when people go
Speaker 1: to the Galapagos. I mean, the main selling point, the
Speaker 1: big deal for everyone seems to be the natural world
Speaker 1: that is avail to you there.
Speaker 2: And despite this modern appreciation for the natural beauty and
Speaker 2: wondrous ecological significance of the Galapagos, a recurring theme among
Speaker 2: early visitors is a reaction exactly the opposite. So in
Speaker 2: the novel Galapagos, Kurt Vonnegut wrote that the early Spanish
Speaker 2: explorers quote did not claim the islands for Spain any
Speaker 2: more than they would have claimed Hell for Spain.
Speaker 1: I haven't read this novel, but I did see it
Speaker 1: in bookstore. There was a nice bookstore on one of
Speaker 1: the islands in the Galapagos, and they had it there.
Speaker 1: They were probably had several Darwin related books, and then
Speaker 1: they had Vonneguts Galapagos, and I was tempted to pick
Speaker 1: it up, but then I was like, I don't know
Speaker 1: if I'm in the mid post apocalyptic literature at the moment.
Speaker 2: I've actually never read that one either, but so, yeah,
Speaker 2: it just seemed like the Spanish were not very interested
Speaker 2: for a while. There were apparently no notable mineral riches
Speaker 2: to mine, at least that they were aware of, no
Speaker 2: people living there to conquer or enslave. There was very
Speaker 2: little fresh water, so the Spanish just did not seem
Speaker 2: very interested in these islands. And during the seventeenth century
Speaker 2: it seems like the Galapagos largely served as a base
Speaker 2: for people who didn't want to be found, for pirates
Speaker 2: and privateers. Privateers would attack Spanish ships to steal the
Speaker 2: gold that the Spanish had stolen from the Incas, or
Speaker 2: just pirates who attacked and raided coastal settlements on the mainland.
Speaker 1: Yeah. Yeah, when it comes to the human history of
Speaker 1: the Glavigos, it's easy to sort of think, oh, well,
Speaker 1: Darwin and then you sort of fast forward to today.
Speaker 1: But yeah, there's a lot of bloody history there. It
Speaker 1: was an extreme location that, like you said, didn't have
Speaker 1: a lot seemingly to offer except as a place of
Speaker 1: refuge for people engaged in various bloody activities. Sometimes it
Speaker 1: seemed like a place for utopian ideals, and of course
Speaker 1: those sorts of ventures don't always turn out well either.
Speaker 1: So yeah, there's there's a very interesting human history there
Speaker 1: that is not all just bird watching by any means.
Speaker 2: Mm hmm. Though, continuing the theme of like the the
Speaker 2: lack of appeal of the islands too many people who
Speaker 2: first arrived there, Charles Darwin himself wrote of his first
Speaker 2: impression of San Cristobal Island that quote, nothing could be
Speaker 2: less inviting.
Speaker 1: That's that's that's funny because they are on San Cristobal Island.
Speaker 1: You know, there's like a statue of Charles Darwin and
Speaker 1: the ship with his hand out and I had my
Speaker 1: I got my picture made with this, of course. But there, yeah,
Speaker 1: there are statues of Darwin all over the islands.
Speaker 2: Nice. Now, well, yeah, I mean, you know, Darwin warmed up,
Speaker 2: you know, he there's a lot to learn there. But
Speaker 2: but yeah, apparently first setting eyes on it, he was like,
Speaker 2: h not cool.
Speaker 1: Yeah, that's not the quote. That's like on a plaque
Speaker 1: beside this statue.
Speaker 2: Now, regarding this story about Burlonga's accidental landfall in the
Speaker 2: Galapagos being the first confirmed human visit, It is important
Speaker 2: to stress that this is the first visit by humans
Speaker 2: we're sure about, but there are all kinds of interesting
Speaker 2: arguments about whether or not others had been there before,
Speaker 2: and their theories of contact regarding the Incas, Pacific peoples
Speaker 2: and so forth. But I think all of these are
Speaker 2: speculative and the evidence is questionable. There was certainly no
Speaker 2: permanent human settlement in pre Columbian times, and the earliest
Speaker 2: arrivals by humans appear to be by accident.
Speaker 1: Yeah, you get into that situation though, where if earlier
Speaker 1: peoples had come there, they probably wouldn't have stuck around,
Speaker 1: and what would they have left behind, what evidence would
Speaker 1: there be, So yeah, we're left to speculation. Now, coming
Speaker 1: back around to the reptiles, which is going to be
Speaker 1: the main thing we're talking about in these episodes. Again,
Speaker 1: the Hawaiian Islands no native reptiles, but we have these
Speaker 1: fascinating examples of reptiles on the Galapagos. So while reptiles
Speaker 1: never had a chance to reach the Hawaiian Islands on
Speaker 1: their own, the Galapagos Islands are in just the right position.
Speaker 1: It seems to have been gifted some wandering, lost at
Speaker 1: sea reptiles, and yet at the same time isolated enough
Speaker 1: that they were able to evolve there unmolested for a
Speaker 1: very long time. So it's kind of fascinating to think
Speaker 1: about that. Like if they had been in any other location,
Speaker 1: you know, there might have been a situation where, yes,
Speaker 1: humans would have found this place and colonized it much earlier.
Speaker 1: It might be in a position where these reptiles would
Speaker 1: not have reached it of their own power or by
Speaker 1: the power of wind and water, which seems to be
Speaker 1: the case. I think the main examples of terrestrial reptiles
Speaker 1: reaching the Galapagos Islands, they tend to involve rafting. They
Speaker 1: tend to involve animals being just swept out to see
Speaker 1: via rivers in South America. And then a number of
Speaker 1: those animals are going to perish, but some of them
Speaker 1: are going to find themselves cast upon a deserted island,
Speaker 1: and from there they begin to find ways to survive
Speaker 1: and these new forms evolve.
Speaker 2: Well, this sounds like a perfect transition to the marine iguana.
Speaker 1: Robert You ready, Yeah, let's talk about the marine iguana.
Speaker 1: Probably not the most famous denizen of the islands, but
Speaker 1: at least number two.
Speaker 2: Yeah, yeah, and certainly maybe the most salient in my
Speaker 2: brain because specifically, to come back to Darwin, Charles Darwin's
Speaker 2: discussion of the marine iguana, or the scientific name ambly
Speaker 2: Rincus Christadis in the Voyage of the Beagle has long
Speaker 2: stuck in my head. So of course, the Voyage of
Speaker 2: the Beagle is the common name used to refer to
Speaker 2: the published writings of Charles Darwin after his sales on
Speaker 2: the HMS b Gole with Captain Fitzroy, and this chapter
Speaker 2: on the Galapagos in the Voyage of the Beagle is
Speaker 2: very famous, but the subsection on the marine iguana has
Speaker 2: long stuck in my head, notably for the weird disrespect
Speaker 2: with which Darwin treats these animals. So I want to
Speaker 2: read a few selections as we go about here from
Speaker 2: this passage in the Beagle, with some abridgments. But to
Speaker 2: start off, this is what Darwin says talking about the
Speaker 2: marine iguana. It is extremely common on all the islands
Speaker 2: throughout the group, and lives exclusively on the rocky sea beaches,
Speaker 2: being never found at least I never saw one even
Speaker 2: ten yards in shore. It is a hideous looking creature
Speaker 2: of a dirty black color, stupid and sluggish in its movements.
Speaker 2: And in his journal he refers to them initially as
Speaker 2: quote large disgusting, clumsy lizards.
Speaker 1: I mean they do lay around in clumps, which I
Speaker 1: could imagine some seeing this as being kind of gross looking.
Speaker 1: But in the same and this on the same note,
Speaker 1: the way they kind of lounge around sometimes they they
Speaker 1: seem oddly human in the way like one all sometimes
Speaker 1: have an arm slung over the shoulder of another, like
Speaker 1: it's like it's two, like as an old married couple
Speaker 1: staring out at the sunset or something. Puppy pile, yeah, yeah,
Speaker 1: kind of a puppy pile. And and there is kind
Speaker 1: of an awkwardness to them sometimes when they move around
Speaker 1: on land. But I don't know, that's kind of charming
Speaker 1: more than anything.
Speaker 2: So early chroniclers often use the same kind of terms.
Speaker 2: They call this animal ugly, hideous. Some of them make
Speaker 2: bizarre value statements, such as comparing them to devils or
Speaker 2: imps of darkness. Uh Darwin himself in the Beagle quote
Speaker 2: say description by a previous author, a Captain Colnett, who
Speaker 2: visited the Galapagos, who says in the part of his
Speaker 2: work that Darwin quotes, quote, they go to sea in
Speaker 2: herds of fishing and sun themselves on the rocks, and
Speaker 2: maybe called alligators in miniature and elsewhere. Coln It marveled
Speaker 2: at their ugliness, writing quote, so disgusting is their appearance
Speaker 2: that no one on board could be prevailed upon to
Speaker 2: take them as food. Not even sailors would eat them.
Speaker 2: And I'm going to say I take personal offense to
Speaker 2: all this. I think marine iguanas are beautiful. I want
Speaker 2: to hug and kiss them. I know I shouldn't. I
Speaker 2: would never do that, but I want to.
Speaker 1: Yeah, they do look kind of like yemps, but I
Speaker 1: think in a good way. We often thought that they
Speaker 1: looked kind of like tiny godzillas. Something about the shape
Speaker 1: of their their heads and their snouts, and of course
Speaker 1: the little, you know, protrusions on the top of their
Speaker 1: head gives them kind of a kaiju appearance. And there's
Speaker 1: so many things about them. There's a lot of times
Speaker 1: you know they're lounging around, they're not doing anything, but
Speaker 1: then when they are moving about, even on the land,
Speaker 1: they can be quite amusing. Like, for instance, if one
Speaker 1: is making a bee line for something, especially if one
Speaker 1: is coming out of the water or it's time to
Speaker 1: go to the water. Sometimes something will seem to get
Speaker 1: in the way of their their journey, like maybe a
Speaker 1: sea lion or a human wanders into their path, and
Speaker 1: they'll just kind of stop and they'll they won't skitter
Speaker 1: out of the way or anything, but there just kind
Speaker 1: of wait until whatever it did is has moved on,
Speaker 1: and then they'll keep going. So there's this kind of
Speaker 1: like laid back care free of energy to these creatures.
Speaker 2: They're kind of wasted away again in Margueritaville.
Speaker 1: Yeah.
Speaker 2: Yeah, by the way, you mentioned their stubby little snouts.
Speaker 2: That's actually what the genus name means, ambly Rincus means
Speaker 2: blunt snout.
Speaker 1: Ah. Well, we'll come back to the blunt snout of that.
Speaker 2: However, to come back to Darwin's writings on the marine
Speaker 2: Iguaana his unseemly anti iguana prejudice aside, he does make
Speaker 2: some correct observations about them. For example, Captain Colnet remembers
Speaker 2: said that they go a fishing in sea herds. You
Speaker 2: know they're going to go out and catch fish. Darwin says,
Speaker 2: I don't know about that. He challenges the idea that
Speaker 2: they eat fish, and in fact we now know they
Speaker 2: do not. Instead, Darwin observes that these animals seem to
Speaker 2: subsist on a kind of seaweed or algae which cannot
Speaker 2: be found on land, and he reasons that this explains
Speaker 2: why they evolved to go to sea in the first place.
Speaker 1: Yeah, and this is spot on, of course, and we'll
Speaker 1: get into it more in a bit, but yeah, and
Speaker 1: it's also very observable if you're watching the creatures, because
Speaker 1: sometimes they're going to be eating algae that's under the
Speaker 1: water and perhaps out of you. But other times it's algae,
Speaker 1: especially as the tides change, it's like partially in partially
Speaker 1: out of the water, so you can see them they're munching,
Speaker 1: grazing on the algae on the rock.
Speaker 2: Though as a side note, Darwin says one dissected iguana
Speaker 2: stomach did have a piece of crab in it, though
Speaker 2: he thinks this might have been eaten by accident, and
Speaker 2: he compares this to cases where a vegetarian tortoise has
Speaker 2: a caterpillar in its stomach, because the caterpillar was just
Speaker 2: on the leafy vegetation the tortoise was eating. In fact,
Speaker 2: we've done whole segments about this on the show before,
Speaker 2: about herbivores eating animals accidentally or even sometimes on purpose.
Speaker 1: Yeah.
Speaker 2: But after introducing them, Darwin goes on to describe the
Speaker 2: animals in detail, describing their movements with a strange mix
Speaker 2: of admiration and disgust. So here's what he says. Quote.
Speaker 2: When in the water, this lizard swims with perfect ease
Speaker 2: and quickness by a serpentine movement of its body and
Speaker 2: flattened tail, the legs being motionless and closely collapsed on
Speaker 2: its sides. A seman on board sank one with a
Speaker 2: heavy weight attached to it, thinking thus to kill it directly,
Speaker 2: But when an hour afterwards he drew up the line,
Speaker 2: it was quite active. Their limbs and strong claws are
Speaker 2: admirably adapted for crawling over the rugged and fissured masses
Speaker 2: of lava which everywhere form the coast. In such situations,
Speaker 2: a group of six or seven of these hideous reptiles
Speaker 2: may oftentimes be seen on the black rocks a few
Speaker 2: feet above the surf, basking in the sun with outstretched legs.
Speaker 2: And then he goes on to note a strange, perplexing,
Speaker 2: almost contradictory observation about their behavior. So, while the iguanas
Speaker 2: go to sea in order to forage, that's how they
Speaker 2: make a living, They swim out in the water, get
Speaker 2: the algae and eat it. He found that he could
Speaker 2: not scare them into the water. If he approached one,
Speaker 2: it would back away from him until it reached the
Speaker 2: edge of a rock hanging over the water. But once
Speaker 2: at that point it would stop retreating. It would just
Speaker 2: let him approach and catch it, rather than flee into
Speaker 2: the water. And here we come to the infamous iguana
Speaker 2: chucking scene of the Voyage of the Beagle. Darwin writes,
Speaker 2: I threw one several times as far as I could
Speaker 2: into a dep pool left by the retiring tide, but
Speaker 2: it invariably returned in a direct line to the spot
Speaker 2: where I stood. It swam near the bottom with a
Speaker 2: very graceful and rapid movement, and occasionally aided itself over
Speaker 2: the uneven ground with its feet. As soon as it
Speaker 2: arrived near the edge, but still being underwater, it tried
Speaker 2: to conceal itself in the tufts of seaweed, or it
Speaker 2: entered some crevice. As soon as it thought the danger
Speaker 2: was past, it crawled out on the dry rocks and
Speaker 2: shuffled away as quickly as it could. I several times
Speaker 2: caught this same lizard by driving it down to a point,
Speaker 2: and though possessed of such perfect powers of diving and swimming,
Speaker 2: nothing would induce it to enter the water, And as
Speaker 2: often as I threw it in, it returned in the
Speaker 2: manner above described. Now, this is indeed a really odd
Speaker 2: bit of behavior, right.
Speaker 1: Yeah, so it would seem. Now, before we get into that,
Speaker 1: I want to just mention I want to make two
Speaker 1: comments about Darwin's riding here. First of all, I do
Speaker 1: get the impression that perhaps Darwin was not a cat
Speaker 1: person or had a cat, because like, this is the same,
Speaker 1: the same situation I think any cat owner can attest to.
Speaker 1: It's like I tried to put the cat where I
Speaker 1: wanted it to be, and it did not want to
Speaker 1: be there. So strange. But on the other hand, I
Speaker 1: do love the part where he talks about how graceful
Speaker 1: they are in the water, because that is also a
Speaker 1: huge tree getting to watch these lizards swim about, because
Speaker 1: it's I mean, it's unlike anything you see with any
Speaker 1: other species on the planet. There's this graceful, indeed serpentine
Speaker 1: movement to them. There whatever awkwardness you might observe on
Speaker 1: the land is not present in the water, and it's
Speaker 1: it's like watching a strange aquatic little dragon move about.
Speaker 2: Well, I think it's also about the way that like
Speaker 2: they anatomically modify themselves to move in the water versus
Speaker 2: on land, because as Darwin says, they collapse their legs
Speaker 2: to the side and almost become a snake in the water.
Speaker 1: Yeah, but with their heads up in a way that
Speaker 1: like you wouldn't mistake it for a snake. Like the
Speaker 1: profile of the swimming marine iguana is unlike anything certainly
Speaker 1: that I've ever seen. So it really stands out in
Speaker 1: your mind, like your mind instantly is identifying that this
Speaker 1: is something different, This is something novel.
Speaker 2: I agree, and having seen not in person but seen
Speaker 2: plenty of video of it. They are beautiful when they're swimming.
Speaker 2: But to come back to this odd behavior, so Darwin says, Okay,
Speaker 2: these things they go in the water all the time,
Speaker 2: that's how they eat. They go down in the water,
Speaker 2: they eat, they come back. How come I can't scare
Speaker 2: one into the water or get it to stay in
Speaker 2: the water by throwing it in. I throw it in,
Speaker 2: the water just comes back out. Darwin comes up with
Speaker 2: the guests about wyat acts this way. He says, quote,
Speaker 2: perhaps this singular piece of apparent stupidity may be accounted
Speaker 2: for by the circumstance that this reptile has no enemy
Speaker 2: whatever on shore, whereas it's at sea it must often
Speaker 2: fall prey to the numerous sharks, hence probably by a
Speaker 2: fixed and hereditary instinct that the shore is its place
Speaker 2: of safety. Whatever the emergency may be, it there takes refuge. So, okay,
Speaker 2: that's an interesting guess. He says. It has natural predators
Speaker 2: in the water, but not on land, so it just
Speaker 2: feels safer on land, even if here I am threatening
Speaker 2: it on land, because it's just acting out of instinct.
Speaker 1: Yeah, yeah, it would seem to be a decent theory.
Speaker 1: And indeed on land that nothing really messes with them
Speaker 1: except when they're smaller. And when they're smaller there you know,
Speaker 1: like and this is the case with a number of
Speaker 1: iguanas and lizards, like until they reach a certain size,
Speaker 1: they're on the menu for various other creatures and birds
Speaker 1: and whatnot. But once they reach a certain maturity. Yeah,
Speaker 1: they can just bask where they want. Nothing's going to
Speaker 1: mess with them.
Speaker 2: Yeah, well, at least in the ancestral environment of the Glasogos.
Speaker 2: Now introduced to dogs and pigs and all that stuff
Speaker 2: that humans brought there will prey on them. So I
Speaker 2: decided to follow up on this and see has there
Speaker 2: been any sub sequent research about this behavior in marine
Speaker 2: iguanas that could confirm or deny Darwin's guess about the
Speaker 2: evolutionary reasoning there. And I found a paper that addresses
Speaker 2: exactly this topic. It is by Edmund S. Hobson called
Speaker 2: Remarks on Aquatic Habitats of the Galapagos Marine Iguana, including
Speaker 2: submergence times, cleaning, symbiosis, and the Shark Threat. This was
Speaker 2: published in a journal called Copeia in nineteen sixty nine,
Speaker 2: and it seems that sharks do occasionally eat the iguanas
Speaker 2: as Darwin guest. A report of the contents of shark's
Speaker 2: stomachs in nineteen oh three by Heller did find some
Speaker 2: marine iguanas in there, but Hobson thinks that the threat
Speaker 2: to iguanas by sharks is mostly exaggerated, given that he
Speaker 2: and his colleagues directly observed iguanas and sharks swimming in
Speaker 2: the same waters side by side, and he says almost
Speaker 2: all the time they just ignore one another entirely. To
Speaker 2: read from Hobson quote to the contrary, the general situation
Speaker 2: finds sharks swimming slowly among smaller fishes with no overt
Speaker 2: sign that they regard these animals as prey. Certainly, sharks
Speaker 2: are efficient predators when they do attack, but situations evoking
Speaker 2: attack are relatively infrequent. At Narborough Island, I saw white
Speaker 2: tipped sharks and a gray shark pass within a few
Speaker 2: meters of surface swimming iguanas, with no indication that they
Speaker 2: regarded the iguanas as prey. George Barlow and I made
Speaker 2: a similar observation involving a large hammer head at Hood Island.
Speaker 2: So if it's not a fear of sharks, what explains
Speaker 2: this behavior?
Speaker 1: Well, if I would a venture a guess, I'd say
Speaker 1: it has to do with temperature, that they're thermic reasons
Speaker 1: at play here.
Speaker 2: Great thinking, and this is exactly what Hobson concludes. Hobson
Speaker 2: argues that the best explanation for this apparently weird behavior
Speaker 2: observed by Darwin is that the water's cold, you know,
Speaker 2: they have to go in there to get food, but
Speaker 2: they don't want to spend any more time in there
Speaker 2: than they have to because it's cold and they're reptiles.
Speaker 2: To read from Hobson, citing another researcher named Bartholomew quote.
Speaker 2: Bartholomew in nineteen sixty six offered a more plausible explanation
Speaker 2: after noting that iguanas basking on the rocks ashore have
Speaker 2: a preferred body temperature of thirty five to thirty seven
Speaker 2: degrees celsius, over ten degrees celsius above that of the sea.
Speaker 2: He suggested that iguanas which are taken from the rocks
Speaker 2: and thrown into the water immediately return to land simply
Speaker 2: because they are reluctant to cool off. And I love
Speaker 2: this explanation. It also does seem plausible to me. But
Speaker 2: I love this because it highlights something about human thinking
Speaker 2: that even Darwin himself was not immune to. And Rob,
Speaker 2: I think you'll know exactly what I'm talking about here.
Speaker 2: When humans are trying to come up with explanations for
Speaker 2: an animal behavior or a feature of an animal body
Speaker 2: or something, I think humans are way too quick to
Speaker 2: jump to two types of explanations, those involving mating and
Speaker 2: those involving predation, sex and violence. Just in our brains,
Speaker 2: sex and violence are more salient explanations than all kinds
Speaker 2: of other pressures that exist in nature and do drive
Speaker 2: animal body plans and animal behaviors. Things having to do
Speaker 2: with just base physical realities of the world, like maintaining
Speaker 2: body temperature, thermoregulation, access to oxygen, all kinds of things
Speaker 2: like that that explain tons about the natural world. It's
Speaker 2: just our brains just don't jump to those things as
Speaker 2: quickly when we're looking for a why.
Speaker 1: Yeah, I think modern reptile enthusiasts, especially any who have
Speaker 1: been engaged in keeping of reptiles, they'll be pretty quick
Speaker 1: to tell you, Oh, yeah, temperature is important, temperature regulation.
Speaker 1: You know, the lizards, snakes, they want their warm places,
Speaker 1: and they're certainly going to realize that. But yeah, this
Speaker 1: is an easy, easy trap to fall into. I should
Speaker 1: also say I did go into the water in the
Speaker 1: Galapagos snorkeling once, and it is, to me a non iguana,
Speaker 1: quite cold. So I can in some way at least
Speaker 1: understand how they feel about it.
Speaker 2: Yeah, so Mark me is convinced I think that iguana
Speaker 2: kept swimming back and crawling out of the water after
Speaker 2: Darwin threw it in because it was getting cold and
Speaker 2: it wanted to it wanted to warm back up on
Speaker 2: the rocks.
Speaker 1: Yeah, and let I say, they're pretty chill, but they're like, no,
Speaker 1: it's too cold. I would like to get out, and
Speaker 1: he's like, I'm throwing you back in. He's like, too cold.
Speaker 1: I wish to get out. It's not time. It's not time.
Speaker 1: I will get in the water when I am warmed
Speaker 1: up enough to do so. Now getting into a little
Speaker 1: bit about the evolution of the marine reptiles, it's very fascinating,
Speaker 1: especially again thinking of them as this really largely singular
Speaker 1: occurrence in the modern world. So I was looking at
Speaker 1: a few different sources. One of these was Marine Reptiles
Speaker 1: by Resmussen at Hall from twenty eleven published in Peel one.
Speaker 1: They point out here that lizards make up sixty percent
Speaker 1: of all reptiles, but very few lizard species compared to say,
Speaker 1: turtles and snakes, are present in our oceans. And this
Speaker 1: isn't getting so much into the issue of prehistoric aquatic reptiles,
Speaker 1: which do include extinct squa mats, like the mosasaur. The mososaurs,
Speaker 1: which were actually distant relatives of modern iguanas and monitor lizards,
Speaker 1: were pretty fascinating in and of themselves. They were gigantic,
Speaker 1: They reached links of up to twelve meters or forty feet.
Speaker 1: They swam in earth oceans roughly sixty six million years ago.
Speaker 1: They hunted other marine reptiles, and it's possible they gave
Speaker 1: birth to live young in the water, though I'm not
Speaker 1: sure this is certain. There's various studies out there about
Speaker 1: possible egg finds of the mosasaurs, but it's worth mentioning
Speaker 1: here to drive home the difference between today's marine reptile
Speaker 1: and those of the past, and especially you know, thinking
Speaker 1: about sea turtles, thinking to about the marine iguana. These
Speaker 1: are animals that, to varying degrees, are great in the water,
Speaker 1: but they still must return to shore to complete some
Speaker 1: vital stage of their life, certainly with sea turtles. With
Speaker 1: the marine iguana, it's more living on the shore but
Speaker 1: then going into the water to graze and feed. Yeah,
Speaker 1: so of extent lizards that are in any way aquatic,
Speaker 1: there are only a few extreme examples, and this includes
Speaker 1: the Western Pacific mangrove monitor, which is a carnivore. But
Speaker 1: as the authors here point out, the Galapagos marine iguana
Speaker 1: is the most aquatic of all extents lizards. It basks,
Speaker 1: breeds and lays eggs on land, et cetera, but it
Speaker 1: has to go into the water to feed. It is,
Speaker 1: by other definitions, the only squaw mate that's actually able
Speaker 1: to exploit the re sources of the ocean in a
Speaker 1: meaningful way. So the aforementioned monitor lizard, for example, can
Speaker 1: catch fish, but it also feeds on terrestrial meats as well.
Speaker 1: I should also note that there are other iguanas on
Speaker 1: the Glabgos Island islands, to be sure, including seven smaller
Speaker 1: species and three species of land iguanas in the genus Conolophus.
Speaker 1: They include the beautiful and rare Galapagos pink iguana, which
Speaker 1: is a most special creature. Included a picture of this
Speaker 1: for you, Joe and everyone out there. You should look
Speaker 1: up a picture of the Galapagos pink iguana. This is
Speaker 1: not something I got to see when I was there,
Speaker 1: because it lives in a very remote part of the islands.
Speaker 1: Not not even even locals don't usually get to see
Speaker 1: this creature.
Speaker 2: The first thing that popped into my head is it
Speaker 2: looks kind of like a hot dog.
Speaker 1: Yeah, yeah, it's you know, it's it's it's it's a
Speaker 1: specially it's an iguana pink. But yeah, these are these
Speaker 1: are rare and beautiful creatures. But again, the marine iguana
Speaker 1: is the real standout here. The other iguanas are a
Speaker 1: lot of fun to watch too, if you if you visit,
Speaker 1: but yeah, the marine iguana is special. The average adult
Speaker 1: is around one point two meters in length, so they're
Speaker 1: not huge, and they're found on virtually every island of
Speaker 1: the Galapagos. So coming back to the question, how did
Speaker 1: any of these lizards get to the Far Flow and
Speaker 1: Galapagos islands, The answer, according to Resmussen at all is
Speaker 1: probably that they're all related to iguanas from South America
Speaker 1: that were washed from the South American mainland, again perhaps
Speaker 1: by river floods, and carried out to the Galapagos. And
Speaker 1: again this is where the Galapagos's isolation yet closer proximity
Speaker 1: to a continental mainland comes into play. The theory is
Speaker 1: also in part supported by the fact that as distinct
Speaker 1: as the four bigger iguanas of the Galapagos Islands, including
Speaker 1: the marine iguana are They are closely related and they
Speaker 1: actually can breed with one another to produce hybrids, so
Speaker 1: hybrids have been reported according to Resmussen. At all, the
Speaker 1: marine iguanas spend quite a bit of time in the water,
Speaker 1: though foraging for their food. As adults, they feed almost
Speaker 1: exclusively on the red and green algae. It's been pointed
Speaker 1: out they're not above at least trying out the odds
Speaker 1: scrap of this, that or the other, and perhaps that
Speaker 1: accounts for the crab claw that Charles Darwin reported. And
Speaker 1: there's at least one population of the marine iguanas that
Speaker 1: has been observed to supplement their diet with land plants.
Speaker 1: But for the most part, their hindgut has evolved to
Speaker 1: thrive on the algae like they're bound to the algae.
Speaker 1: This is not just a this is not just a
Speaker 1: lifestyle choice at this point, and their bodies have adapted
Speaker 1: in other key ways as well to allow this marine
Speaker 1: diet due to the considerable selection pressure that's been applied
Speaker 1: to them, which is quite literally the selection pressure of
Speaker 1: being cast upon a resource depleted island. So we mentioned
Speaker 1: their flattened tail that's one of the adaptations. And it's
Speaker 1: not like you don't find flattened tails and other lizard species,
Speaker 1: but this is clearly something that seems to help out
Speaker 1: there swimming. They also have limited webbing on their feet,
Speaker 1: which I saw kind of two different takes on this
Speaker 1: in the literature I was looking at. On one hand,
Speaker 1: there's the argument like, yeah, it's partially web feet, this
Speaker 1: is going to help them swim, But others say, well,
Speaker 1: the webbing is not that extensive. It maybe helps a
Speaker 1: little bit, but let's not overstress its importance.
Speaker 2: Well, I'm no marine iguana expert, but it seems to me,
Speaker 2: at least when I've seen images of them swimming, it
Speaker 2: doesn't seem like they paddle with their feet much at
Speaker 2: all that I recall, but maybe they do sometimes.
Speaker 1: Something that everyone agrees on, though, is that their claws
Speaker 1: have become more powerful to allow them to grip the
Speaker 1: rocks and the surf during feeding. And this is certainly
Speaker 1: key because if you're observing one from the shore, or
Speaker 1: if you're looking at images or footage of them, or
Speaker 1: if you're snorkeling, you get to see one underwater. I
Speaker 1: did not get to see one underwater. Firsthand. But either way,
Speaker 1: when they're feeding, they're often in an area where the
Speaker 1: the you know, the surf is disrupting them and would
Speaker 1: make it difficult to feed if they were not able
Speaker 1: to hold on and latch on. And then of course
Speaker 1: when they get in or out of the surf, they're
Speaker 1: going to need to keep from being swept up anyway.
Speaker 1: So yeah, they got to have those powerful claws to
Speaker 1: aid them.
Speaker 2: That's not an easy lifestyle. And crawling out of the
Speaker 2: surf onto rocks, I mean, think about how danger its
Speaker 2: how dangerous it would be to try to land a
Speaker 2: boat or even just swim up onto jagged rocks as
Speaker 2: the tide is coming in and out.
Speaker 1: Yeah, for sure. I was also now, this is something
Speaker 1: I was told by one of the guides in the
Speaker 1: Galapagos Island, who again are very knowledgeable of all of this.
Speaker 1: Uh so, you know, they're they're very quick to spout
Speaker 1: out all the scientific names of all the creatures you're
Speaker 1: looking at, and they're they're up on the latest findings
Speaker 1: and so forth. I was pointed out that they all
Speaker 1: utilize those sort of thorny spikes on their head, and
Speaker 1: I almost hesitate to say face in order to loosen
Speaker 1: up the algae on the rocks by sort of rubbing
Speaker 1: their heads against it. And then it should also be
Speaker 1: noted we touched on this earlier, but there's the whole
Speaker 1: regulation of their body temperature. And this is key because
Speaker 1: again the water's cold, and these are cold blooded animals,
Speaker 1: so they spend a fair amount of time basking in
Speaker 1: the sun. And the way this is certainly one way
Speaker 1: it was described to me there, and this is backed
Speaker 1: up in the paper that I was reading recently, is
Speaker 1: that in order to go into the water, they kind
Speaker 1: of have to power up, so like they're powering up
Speaker 1: there like on the on the beach or on the rocks,
Speaker 1: basking in the sun, kind of filling their batteries up
Speaker 1: all the way. And then when it's time, well then
Speaker 1: it's time. Now it is time to go into the
Speaker 1: water to forage for food, and they make that beeline.
Speaker 1: But it's only then, only then, and they're not going
Speaker 1: to be thrown in early by some deranged englishmen there.
Speaker 1: And if something should get in their way, well they're
Speaker 1: just going to wait patiently for a little bit. But
Speaker 1: they've got a place to be. It is time to
Speaker 1: go into the water and feed, So.
Speaker 2: It's a constant trade off of managing different energy resources
Speaker 2: in the body. You've got your thermal energy, like you
Speaker 2: need to bask on the land to get your body
Speaker 2: temperature up, but then you need to go into the
Speaker 2: water to get food for your metabolism, and you're sort
Speaker 2: of just always trading back and forth between the two.
Speaker 1: Yeah, Now when they're in the water, their heart beats
Speaker 1: also reduce from about forty three beats per minute on
Speaker 1: land to seven to nine beats per minute in the water,
Speaker 1: So that's also an interesting adaptation they have. And then
Speaker 1: this is another famous one that's a lot of fun
Speaker 1: to watch. You see this in footage every nature documentary
Speaker 1: that's covered marine iguanas. But both of the main varieties
Speaker 1: found in the four larger iguanas they have salt glands
Speaker 1: that help them process an abundance of salt should it
Speaker 1: be in the body. But with the marine iguanas, this
Speaker 1: of course is very visual because if you're just watching
Speaker 1: them lounge about, they're going to regularly appear to sneeze.
Speaker 1: They're not sneezing, they're blasting salt out of these salt glands.
Speaker 1: They basically blasting salt out of their nostrils as they
Speaker 1: lounge about on their rocks, and as they're doing this too,
Speaker 1: making these cute little sneezing sounds or gross little sneezing
Speaker 1: sounds everyone to look at it. They're also kind of
Speaker 1: like crusting over the tops of their heads with this,
Speaker 1: you know, like white salt crystals, so you can tell
Speaker 1: like which ones haven't been on the in the water
Speaker 1: that recently, because they have this kind of like salty
Speaker 1: look to their heads.
Speaker 2: They got the salt snot on there. Yeah, you know,
Speaker 2: this comes back to something else Darwin said. He was like, there,
Speaker 2: you know, you can back them into a corner and
Speaker 2: you can catch them. They they don't really bite. I
Speaker 2: don't think that's true, by the way, but he says,
Speaker 2: they don't really bite, but they will blow salt out
Speaker 2: of their noses at you.
Speaker 1: Yes, I I remember reading this as well, because I
Speaker 1: was when we were in the Galabacos. I pulled up
Speaker 1: the text. I was reading it, and yeah, there is
Speaker 1: this accusation that they're doing it defensively, and yeah, this
Speaker 1: does not seem to be the case. Now they're just
Speaker 1: doing it. Maybe they're doing it, I guess, I guess
Speaker 1: I have no data on this, but I guess it's
Speaker 1: possible that if someone is coming at them and backing
Speaker 1: them away, then maybe that does seem to incite a
Speaker 1: snort because they're about to move. But other than that, yeah,
Speaker 1: there's I've seen nothing to indicate that this is in
Speaker 1: any way a self defense measure.
Speaker 2: That's right up there with av and defensive vomiting.
Speaker 1: Yeah. Yeah, there's a lot of back and forth on that, right.
Speaker 1: I think we've discussed that is like a vulture vomiting
Speaker 1: in order to free up room and you know, make
Speaker 1: itself lighter so it can take off and get away.
Speaker 1: Is that are offering a bribe to a scavenger that
Speaker 1: may be coming after them and decide to go for
Speaker 1: vomit instead of fighting a buzzard like There are various
Speaker 1: interpretations of that. As I recall now on the issue
Speaker 1: of marine iguana evolution, I was looking at another source.
Speaker 1: This is from Martin Wakelski in a two thousand and
Speaker 1: five edition of the Royal Society paper entitled Evolution of
Speaker 1: body Size in Galapagoes marine Iguanas, and I found this
Speaker 1: one interesting because the author here lays out one possible
Speaker 1: model for how the Marinea iguanas evolved. So, first of all,
Speaker 1: iguanas arrived, according to this theoretical model, in the Galapagoes,
Speaker 1: perhaps ten to fifteen million years ago from South America
Speaker 1: via rafting, so swept out to see floating on some
Speaker 1: vegetation and so forth, and then being cast on this
Speaker 1: strange island. And once they're there, it becomes clear eventually
Speaker 1: here that in the intertidal zone there's plenty of food
Speaker 1: for iguanas, but it's not on the land, it's the
Speaker 1: algae in the water. Initially, the iguanas are going to
Speaker 1: have to depend on low tides to get to the food,
Speaker 1: so the tide goes down, iguanas are daring to get
Speaker 1: down in there and go after the algae, and so
Speaker 1: there's going to but from there that's where we're going
Speaker 1: to be to see the selection pressure towards larger bodies
Speaker 1: for thermal inertia and also the ability to anchor themselves
Speaker 1: in the surf, as well as these other adaptations that
Speaker 1: we mentioned, like the bigger claws ultimately the shorter snout
Speaker 1: as well. That's going to be part of their their
Speaker 1: forging behaviors. They essentially like rub their faces against the
Speaker 1: rocks to gnaw off the algae as well as the
Speaker 1: like swimming morphological changes.
Speaker 2: Interesting.
Speaker 1: Yeah, there's and there's there's actually a lot of a
Speaker 1: lot of work that comes out related to the marine iguanas,
Speaker 1: Like there's no shortage of papers. There's one from twenty
Speaker 1: twenty one that I was looking at, Cranial Anatomy of
Speaker 1: the Galapagos Marine Iguana by Paparella and Caldwell in the
Speaker 1: American Association for Anatomy, and they point out some of
Speaker 1: the you know, the key changes just to the head
Speaker 1: of the creature of VI. It's evolution modified configuration of
Speaker 1: the snout and nasal chamber, increased muscle attachments in the
Speaker 1: temporal post orbital region of the skull, and and also
Speaker 1: the teeth as well. So all of this is coming
Speaker 1: seems to revolve around what they're feeding on and how
Speaker 1: they're feeding on and how that's affecting just like the
Speaker 1: overall shape and even like the muscles of the head.
Speaker 2: And I imagine they would make some guesses from this
Speaker 2: about how far back in time the marine iguanas had
Speaker 2: these evolutionary changes.
Speaker 1: Yeah, one of the authors here, Paparella, I found this
Speaker 1: is actually I believe from another paper. But I saw
Speaker 1: this author saying that arguing elsewhere for an iguana colonization
Speaker 1: of the ancient Galapagos Islands as far back as twenty
Speaker 1: to twenty five million years ago. And I think in
Speaker 1: this we're getting into into this idea of not only
Speaker 1: the existing Galapagos Island, but these like pre existing Galapagos islands,
Speaker 1: the ones that, like you said, have now been lost
Speaker 1: and are submerged. Wrote that like this we would have
Speaker 1: like an initial dispersal followed by constant short range hopping
Speaker 1: from older to newer islands. So you know, they get
Speaker 1: a foothole in one place and then they can spread
Speaker 1: to these other islands much more easily. And then as
Speaker 1: new islands emerge, that opens up new places for them
Speaker 1: to be. And of course as old islands die away,
Speaker 1: then so do the populations of those islands or they
Speaker 1: you know, they're forced to disperse to newer islands. And
Speaker 1: Joe from that paper about the shape of their heads,
Speaker 1: I included this wonderful image, this one. I think I
Speaker 1: didn't get this out of the paper itself, but this
Speaker 1: was I believe from a like a Twitter post by
Speaker 1: the American Association for anatomy. It's out there if anyone
Speaker 1: wants to look it up for themselves. But yeah, you
Speaker 1: see very very high definition close up on both the
Speaker 1: head of the marine iguana, and then also a comparison
Speaker 1: of the skull, which I thought was just very insightful
Speaker 1: looking at these, because you know, it just looks it
Speaker 1: looks very much unlike a lot of the lizard skulls
Speaker 1: you might see, Like glancing at it, you might not
Speaker 1: even think of it as a lizard's call. I mean,
Speaker 1: it doesn't look like a human skull or anything. It's distinct,
Speaker 1: but you can clearly see like the changes that have
Speaker 1: taken place here.
Speaker 2: Yeah, the blunt snout and the density of it, I
Speaker 2: mean almost you could imagine it being more of a
Speaker 2: turtle skull or again, I mean it looks kind of
Speaker 2: like Godzilla.
Speaker 1: Yeah, it's like Godzilla, and I like how they kind
Speaker 1: of have. You see, especially in close up like these,
Speaker 1: there's real sense of iguana lips, you know.
Speaker 2: Yeah, you also get a really good look up inside
Speaker 2: the nostrils.
Speaker 1: Yeah, this, of course is a specimen. This is a
Speaker 1: dead iguana that Joe and I are gawking at here,
Speaker 1: but still beautiful specimen but yeah, the marine iguanas are
Speaker 1: are special creatures. And I think I don't even have
Speaker 1: to tell anyone this. It's this is not new information. Uh.
Speaker 1: There have been so many documentaries that of course have
Speaker 1: covered the Galacos Islands that have caught brilliant footage of them.
Speaker 1: They are a standout species that they've been highlighted in
Speaker 1: various shows over time, or you've no doubt seen articles
Speaker 1: about them or see them popping up in the lists.
Speaker 1: So so yeah, nothing nothing new in me saying that
Speaker 1: these animals are great. But like all these things, yeah,
Speaker 1: if you get to see them in person, if you
Speaker 1: have that chance, take that opportunity, because they're pretty remarkable.
Speaker 2: I would like to see the iguana puppy pile. Hey,
Speaker 2: we haven't even touched on the most famous reptiles of
Speaker 2: the Galapagos, and I think we're gonna have to do
Speaker 2: that in the next episode.
Speaker 1: That's right, the Galapagoes tortoise. Yeah, we're going to come
Speaker 1: back in the next episode of of this journey to
Speaker 1: discuss these fabulous creatures. I mean, it makes sense that
Speaker 1: they'd come in second. They are slower, but they're they're
Speaker 1: very remarkable in their own way, so be sure to
Speaker 1: come back for that episode. In the meantime, we'd love
Speaker 1: to hear from you if you have thoughts about Marine
Speaker 1: iguanas you know firsthand or docum menory based. If you're
Speaker 1: a resident of Ecuador the Glavigos Islands, certainly we would
Speaker 1: love to hear from you on all of this. If
Speaker 1: you want to hear more Stuff to Blow Your Mind,
Speaker 1: I'll just remind you that core episodes of the show
Speaker 1: publish on Tuesdays and Thursdays, and the Stuff to Blow
Speaker 1: Your Mind podcast feed on Mondays. We do listener mail.
Speaker 1: On Wednesdays we do a short form artifact or monster fact,
Speaker 1: and on Fridays we do Weird House Cinema. That's our
Speaker 1: time to set aside most of the serious science and
Speaker 1: so forth and just talk about a strange film.
Speaker 2: Huge thanks to our audio producer, Max Williams. If you
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Speaker 2: on this episode or any other, to suggest a topic
Speaker 2: for the future, or just to say hello, you can
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