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Speaker 1: Hey you welcome to Stuff to Blow Your Mind. My

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Speaker 1: name is Robert.

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Speaker 2: Lamb and I am Joe McCormick, and today we're bringing

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Speaker 2: you an episode from the vault. This is part two

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Speaker 2: of our series on the reptiles of the Galapagos. This

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Speaker 2: was originally published December tenth, twenty twenty two.

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Speaker 3: Enjoy Welcome to Stuff to Blow Your Mind, production of iHeartRadio.

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Speaker 1: Hey, welcome to Stuff to Blow your Mind. My name

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Speaker 1: is Robert.

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Speaker 2: Lamb and I'm Joe McCormick, and we're back with part

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Speaker 2: two of our series on the reptiles of the Galapagos Islands. Now,

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Speaker 2: in the previous episode, we focused mainly on the marine iguana,

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Speaker 2: or as they were often referred to early on, those

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Speaker 2: hideous creatures, those stupid, awful, sluggish lizards. We mounted a

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Speaker 2: defense of the marine iguana. But today we are here

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Speaker 2: to talk about the Galapagos tortoise. And I wanted to

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Speaker 2: kick things off by reading a passage from Charles Darwin

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Speaker 2: in the Voyage of the Beagle. Darwin, of course, was

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Speaker 2: not just a great scientist, but a really wonderful writer,

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Speaker 2: and I think this will help set the scene. So

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Speaker 2: are you ready to hear about Darwin's first vision of

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Speaker 2: San Cristobal Island. Then then what they called Chatham Island.

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Speaker 1: Yeah, let's let's hear from from old Charles.

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Speaker 2: And this is part of a narrative of when he

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Speaker 2: slept ashore one night on the island. So off the boat,

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Speaker 2: Darwin writes. The entire surface of this part of the

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Speaker 2: island seems to have been permeated like a sieve by

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Speaker 2: the subterranean vapors. Here and there the lava, whilstsoft, has

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Speaker 2: been blown into great bubbles, and in other parts the

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Speaker 2: tops of caverns similarly formed have fallen in, leaving circular

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Speaker 2: pits with steep sides. From the regular form of the

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Speaker 2: many craters. They gave to the country an artificial appearance

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Speaker 2: which vividly reminded me of those parts of Staffordshire, where

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Speaker 2: the great iron foundries are most numerous. The day was

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Speaker 2: growing hot, and the scrambling over the rough surface and

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Speaker 2: through the intricate thickets was very fatiguing, but I was

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Speaker 2: well repaid by the strange Cyclopean scene. As I was

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Speaker 2: walking along, I met two large tortoises, each of which

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Speaker 2: must have weighed at least two hundred pounds. One was

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Speaker 2: eating a piece of cactus, and as I approached, it

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Speaker 2: stared at me and slowly walked away.

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Speaker 4: The other gave a.

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Speaker 2: Deep hiss and drew in its head. These huge reptiles,

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Speaker 2: surrounded by the black lava, the leafless shrubs and large

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Speaker 2: cacti seemed to my fancy like some Antediluvian animals. The

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Speaker 2: few dull colored birds cared no more for me than

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Speaker 2: they did for the great tortoises. So Darwin transported to

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Speaker 2: a time from before Noah's flood by the vision of

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Speaker 2: these bizarre, gigantic tortoises crawling around on the on the lava.

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Speaker 1: Yes, this is the great sceni paints here and and yeah.

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Speaker 1: As I mentioned in the first episode, I was. I

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Speaker 1: was fortunate enough to get to travel to the Galapagos

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Speaker 1: Islands just a couple of months ago. In San Cristobo

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Speaker 1: Island was one of the islands that I got to visit,

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Speaker 1: and this was pretty much the the experience I had

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Speaker 1: with my family walking through one of the the areas

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Speaker 1: they had set aside for these magnificent tortoises. They're just

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Speaker 1: they just they walk around as if yeah, if you

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Speaker 1: don't matter, unless you get a little too close for

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Speaker 1: their liking, in which case there'll often be this hiss

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Speaker 1: and this retraction of their head. I mean, their heads

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Speaker 1: don't retract in the same way that say, a box

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Speaker 1: turtle does, but they're able to sort of pull their

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Speaker 1: head in a bit. But that the hissing that Darwin

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Speaker 1: is describing here, it does have a very, I don't know,

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Speaker 1: pneumatic kind of quality to it. It feels it sounds

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Speaker 1: like some sort of machinery. And indeed, that's that's kind

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Speaker 1: of more what it is, as opposed to like the

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Speaker 1: hiss you might hear from a house cat or something.

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Speaker 1: And one of the things that I kept thinking about

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Speaker 1: while encountering them is that they already move with this

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Speaker 1: kind of herky jerky kind of locomotion. They already move

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Speaker 1: like they are elaborate mechanical creatures created for practical effects

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Speaker 1: for a nineteen nineties science fiction feature. And then they

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Speaker 1: also make this hissing sound to move part of their anatomy.

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Speaker 1: So it almost creates this feeling of am I seeing

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Speaker 1: real animals or is this an elaborate hoax these animatronics? Yeah, yeah, yeah,

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Speaker 1: they feel almost like animatronics, but of course they're they're

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Speaker 1: they're they're quite alive, and they're quite, but that's part

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Speaker 1: of their strangeness, and they just the awe of watching

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Speaker 1: these giant creatures walk arou around, slowly, eat, and occasionally

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Speaker 1: have some startling interactions.

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Speaker 2: Now I'm greatly envious of the opportunity you got to

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Speaker 2: see these animals in person, but I trust that you

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Speaker 2: did not do what Darwin did upon encountering these beasts

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Speaker 2: and try to ride them.

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Speaker 1: Absolutely not, no, no. The only time the times we

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Speaker 1: were forced to get uncomfortably close in one of these

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Speaker 1: situations of the area that we were walking through had

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Speaker 1: a path and you're supposed to stay on the path

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Speaker 1: and keep your distance from the tortoises. Sometimes though the

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Speaker 1: tortoises will just get on the path. You have to

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Speaker 1: find your way around them, and they don't necessarily like that.

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Speaker 1: But we kept our distance, and you want to keep

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Speaker 1: your distance because, yeah, if you get a little too close,

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Speaker 1: they're going to stop interacting with their environment for a

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Speaker 1: little bit. And if you don't want to watch that,

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Speaker 1: you want to watch them eat and rampage around and

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Speaker 1: occasionally have these fabulous stare downs between two males which

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Speaker 1: I don't know, we may describe this later, So maybe

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Speaker 1: I shouldn't get into that just yet.

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Speaker 2: Yeah, yeah, we can talk about the mock fights later on.

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Speaker 2: So the Galapagos tortoise is I think you would say,

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Speaker 2: originally the dominant land herbivore of the Galapagos Islands, which

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Speaker 2: makes them kind of unique because there's pretty much nowhere

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Speaker 2: else on Earth now where the dominant land herbivore is

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Speaker 2: a reptile. So these are very unique and beautiful creatures,

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Speaker 2: and the Glapagos tortoise stands out so much among the

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Speaker 2: endemic fauna that it's actually the origin of the archipelago's

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Speaker 2: name in one way or another. There's a little bit

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Speaker 2: of nitpicking on that, but basically it goes like this.

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Speaker 2: By the fifteen seventies, these islands had already appeared on

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Speaker 2: at least a couple of European maps. The one I

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Speaker 2: saw named was by a Flemish cartographer named Abraham Ortelius,

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Speaker 2: and it named the islands Insulae de los galapago or

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Speaker 2: meaning Islands of the Tortoises. Now, the nitpicking about the

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Speaker 2: terminology I've read is what exactly the word galapago or

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Speaker 2: Galapagos originally meant. According to a book that I'm going

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Speaker 2: to reference multiple times in this episode, Galapagos and Natural History,

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Speaker 2: second Edition by John Creecher and Kevin Laughlin from Princeton

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Speaker 2: University Press. That editions out just twenty twenty two. They

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Speaker 2: write that the origin of the name of the islands

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Speaker 2: is an old Spanish word, galapago, which was a name

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Speaker 2: for a specific type of saddle. So there's like, you know,

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Speaker 2: a saddle you'd use on a horse. I guess that

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Speaker 2: has a kind of upturned front. That was a galapago.

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Speaker 2: And some, but not all, of the Galapagos tortoises have

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Speaker 2: saddle shaped shells. Others have a more straightforward dome. And

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Speaker 2: we can talk about the evolutionary reasons for those differences

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Speaker 2: later on. But when Tamas de Berlanga landed on the

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Speaker 2: islands in fifteen thirty five, a story we talked about

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Speaker 2: in the previous episode. After this, he wrote a letter

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Speaker 2: to the king in which he observed describing the animals

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Speaker 2: of the island, he observed mucos lobos marinos meaning many

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Speaker 2: sea lions, tortugas meaning sea turtles, iguanas, and Galapagos, and

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Speaker 2: the authors write that this is probably a reference to

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Speaker 2: the tortoises and their saddle shaped shells rather than to

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Speaker 2: literal saddles being on the island.

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Speaker 1: This is a solid observation that thankfully still holds true today.

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Speaker 1: Mucos lobos marinos and tortugas, iguanas and tortoises. Yes, yeah,

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Speaker 1: the sea lion, I mean the mucco lobos marinos. That

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Speaker 1: was probably the most astounding of all when you're near

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Speaker 1: the coast, because they're everywhere and sometimes laying. There'll be

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Speaker 1: like a male that's come up and he's like laying

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Speaker 1: in the street, or they they love park benches. There

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Speaker 1: are a lot of fun to wide.

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Speaker 4: Well.

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Speaker 2: The difference in the Spanish name. I guess if it's

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Speaker 2: lobo marino that would mean see wolf, not sea lion, right,

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Speaker 2: But that that heightens the kind of implicit comedy of

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Speaker 2: naming these animals after what you would think of as

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Speaker 2: a more actively voracious land predator, whereas you know, I

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Speaker 2: guess when they're on the land, they're not quite so

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Speaker 2: threatening as maybe a wolf for a lion would seem.

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Speaker 1: Yeah, I mean, well, on one hand, yeah, you have

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Speaker 1: some of the little tiny islands are at least one

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Speaker 1: that's named for the wolves for the lobos, and of

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Speaker 1: course that's why, because sea lions are hanging out there

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Speaker 1: and yeah, on the on the on the beach. They're

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Speaker 1: often quite docile and you see people getting way too

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Speaker 1: close to them in some cases. But the big males,

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Speaker 1: of course, are very territorial about hanging on to their

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Speaker 1: bit of property and their and their females, you know,

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Speaker 1: their their their beach real estate, and so there of

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Speaker 1: course always they're continuously loudly sending the alarm and occasionally

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Speaker 1: chasing off other males. So there's there's a lot of

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Speaker 1: drama if you just sit back and watch the sea lions.

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Speaker 1: And I imagine that listeners from other parts of the

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Speaker 1: world can to this as well.

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Speaker 2: Yes, yes, keep your distance, folks, I mean, observe, but

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Speaker 2: there's no reason to get in the sea lion space.

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Speaker 1: Though sometimes in my experience, sea lion will come for

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Speaker 1: your space. I was just seated away from sea lions

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Speaker 1: and then here comes this female and she's just howling

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Speaker 1: about something and insists on taking my spot on a log,

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Speaker 1: and I'm like, it's yours at yours, and then she

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Speaker 1: just hangs out on the log for a few minutes

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Speaker 1: and then leaves it. I don't know, She's just trying

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Speaker 1: to make a point.

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Speaker 2: So if you have never seen the Galopagos tortoises before,

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Speaker 2: you can easily find lots of pictures of them. But

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Speaker 2: to briefly describe the adults, there are many different species

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Speaker 2: scattered across the different islands. Maybe we can get into

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Speaker 2: the exact numbers on that in a bit, but generally

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Speaker 2: what they all have in common is that they're very large.

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Speaker 2: They have large shells, some species with rounded dome tops,

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Speaker 2: others with the saddle shape that Burlonga probably observed, which

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Speaker 2: are typically turned up in the front to have a

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Speaker 2: kind of big notch above the animal's head and neck.

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Speaker 2: They have long, dry, wrinkly necks which are surprisingly slim,

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Speaker 2: almost I dare say snake like in a way. They

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Speaker 2: have blunt, round snouts and a beak like mouth with

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Speaker 2: no teeth, and everywhere you can see their their skin.

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Speaker 2: In between the shell parts there is typically a lot

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Speaker 2: of leathery, wrinkly flesh, which just makes them look like

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Speaker 2: old people.

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Speaker 1: Yeah, they they have this kind of appearance of a

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Speaker 1: of acute shriveled old person.

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Speaker 4: Vase.

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Speaker 1: Uh. They're they're very They're very sweet to look at

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Speaker 1: it's it's it's kind of hard to to not anthropomorphize

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Speaker 1: them as such even and and that can, of course,

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Speaker 1: can become complicated when you start considering like the full

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Speaker 1: range of their of their lifestyle and the way that

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Speaker 1: they they live and reproduce and so forth. Uh, it

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Speaker 1: never pays to anthropomorphize creatures too much.

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Speaker 4: Yeah.

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Speaker 2: Now, no one thing many of us today might not appreciate,

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Speaker 2: even if you go to the Galapagos today or if

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Speaker 2: you see Good Nature documentary footage from there, is how

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Speaker 2: many tortoises there were when people first arrive, Before the

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Speaker 2: animals had any natural predators other than the threat post

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Speaker 2: to hatchlings by the Galapagos Hulk, this place was swarming

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Speaker 2: with tortoises. And to try to get a picture of that,

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Speaker 2: I wanted to cite some basically math work that Creature

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Speaker 2: and Laughlin do in their book. So they're talking about

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Speaker 2: the reproductive rates of these tortoises. So they say, if

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Speaker 2: a female tortoise has more than two young that survive

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Speaker 2: into adulthood, the tortoise population will grow, so she has

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Speaker 2: replaced both her and her mate. And if she has

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Speaker 2: more than one, the population will grow and they say, Now,

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Speaker 2: consider that a female tortoise may conservatively lay five to

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Speaker 2: ten eggs annually for perhaps eighty years or more. So,

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Speaker 2: just for a very conservative estimate, they say, Okay, imagine

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Speaker 2: she averages one annual clutch and there's just three eggs

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Speaker 2: in it. That's kind of a small estimate. But there's

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Speaker 2: just three eggs per clutch. That's more than two hundred

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Speaker 2: eggs in a single adult female tortoises lifetime. They say, realistically,

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Speaker 2: the number is probably a multiple of that. So they're

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Speaker 2: going to have a lot of young and there before

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Speaker 2: humans arrive and bring their invasive species with them, before

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Speaker 2: they bring dogs and pigs and stuff. There is not

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Speaker 2: significant predation at any life cycle. A part of the

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Speaker 2: life cycle of a tortoise. There's some minor predation by

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Speaker 2: like hawks of the babies, but most of them are

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Speaker 2: going to grow and become reproducing adults.

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Speaker 1: Yeah, it's pretty amazing. Amazing. I ask one of the

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Speaker 1: guides about, you know, how long are the females reproductive?

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Speaker 1: Because you see some very who was pointed that My

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Speaker 1: guide here was pointing out the various the old tortoises.

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Speaker 1: But because you can sort of tell by looking at

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Speaker 1: their shells the way that the line, like, for a while,

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Speaker 1: you can sort of it's not like you can count

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Speaker 1: the rings exactly, but you can sort of see the

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Speaker 1: rings and the patterns on their shell. But eventually there's

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Speaker 1: kind of like a smoothing out that occurs, and those

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Speaker 1: are the really old ones. And the guy was like, yeah,

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Speaker 1: we're not entirely sure, but it seems like they're reproductively

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Speaker 1: active for pretty much most of their lives, which is

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Speaker 1: the astounding.

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Speaker 2: Yeah, it's amazing. And so the authors of this book

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Speaker 2: end up concluding that before humans arrived and brought these

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Speaker 2: invasive predators with them and started harvesting the tortoises themselves,

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Speaker 2: which is a sad fact we'll talk about in a moment,

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Speaker 2: the tortoises.

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Speaker 4: Were just.

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Speaker 2: Profuse.

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Speaker 4: They were everywhere.

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Speaker 2: They say, there's a conserva estimate of a total population

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Speaker 2: of two hundred and fifty thousand tortoises just on this

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Speaker 2: small group of islands. But of course, today all of

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Speaker 2: these tortoise populations are at least vulnerable, and some are

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Speaker 2: up to critically endangered, and that's after a significant bounce

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Speaker 2: back in some cases, you know, after conservation efforts kicked in.

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Speaker 2: So what happened to these tortoises. Well, one thing that

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Speaker 2: happened is is something Darwin talks about in his Passage

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Speaker 2: and Voyage of the Beagle. Before he even really gets

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Speaker 2: to ecological observations about the tortoises, he writes at length

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Speaker 2: about people eating them. So, in describing the small human

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Speaker 2: colony on what was then Charles Island what today is

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Speaker 2: called Floriana Island, so Darwin writes, in the woods there

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Speaker 2: are many wild pigs and goats. Now remember those are

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Speaker 2: not native to the islands, but introduced by humans. Darwin

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Speaker 2: goes on, But the staple article of animal food is

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Speaker 2: supplied by the tortoises. Their numbers have of course been

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Speaker 2: greatly reduced in this island, but the people yet count

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Speaker 2: on two days hunting, giving them food for.

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Speaker 4: The rest of the week.

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Speaker 2: It is said that formerly single vessels have taken away

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Speaker 2: as many as seven hundred, and that the ship's company

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Speaker 2: of a frigate some years since brought down in one

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Speaker 2: day two hundred tortoises to the beach. And this brings

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Speaker 2: us to a very sad fact about the human use

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Speaker 2: of tortoises. Here that tortoises were, of course very good

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Speaker 2: meat sources for sailing vessels, but this was especially due

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Speaker 2: to the fact that because turtles have a very slow metabolism,

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Speaker 2: and they could be loaded into the ship alive and

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Speaker 2: then would survive for an extremely long time without food

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Speaker 2: or water in the hold. And it's important to remember that,

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Speaker 2: of course, ships at the time didn't have refrigerators or

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Speaker 2: freezers or other sophisticated food preservation techniques beyond things like

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Speaker 2: the nuclear option salting.

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Speaker 1: Yeah. Yeah, so this is quite sad to picture, because

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Speaker 1: on one hand, it's not like these tortoises were wandering

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Speaker 1: around on deck. They were stuffed below I think generally

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Speaker 1: upside down and just stored away as living casks of

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Speaker 1: food because they could live for up to a year

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Speaker 1: without food or water, which is just crazy to think about,

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Speaker 1: but also just unimaginately cruel to imagine them down there.

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Speaker 1: And on top of this, one of the other troublesome

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Speaker 1: things about this for the tortoises is that the sailors

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Speaker 1: would tend to grab the tortoises they could easily carry

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Speaker 1: back to the ship, which meant that they tended to

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Speaker 1: focus on the smaller tortoises and leave the bigger ones.

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Speaker 1: This meant that they were favoring female tortoises over male tortoises,

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Speaker 1: and I guess to a certain extent also younger male tortoises,

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Speaker 1: but certainly skewing more towards female tortoises, thus destabilizing the

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Speaker 1: species even more than if they had managed more of

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Speaker 1: a fifty to fifty split between the tortoise genders.

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Speaker 2: Yeah, so unfortunately a lot of tortoises were removed from

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Speaker 2: the islands that way, but also they just remained a

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Speaker 2: live meat source for hunting by the locals, and Darwin

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Speaker 2: tells many interesting stories about this. For example, he writes

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Speaker 2: about a time that he went up to one of

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Speaker 2: the highland regions of one of the islands, and he

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Speaker 2: hung out in a hovel that had been built by

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Speaker 2: two men there who spent their time hunting tortoises. And

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Speaker 2: so he visits these guys and he sleeps there in

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Speaker 2: the hovel one night, and what did he eat while

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Speaker 2: he was there, Well, exclusively tortoise meat. That was the

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Speaker 2: entire menu, about which he says, quote the breastplate roasted

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Speaker 2: as the gauchos do carne conquero, which I think means

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Speaker 2: meat with leather with the flesh on. It is very good,

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Speaker 2: and the young tortoises make excellent soup, but otherwise the meat,

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Speaker 2: to my taste, is indifferent.

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Speaker 1: Oh well, there you go. Also taking the harvesting the

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Speaker 1: young tortoises, that's great as well.

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Speaker 2: But they apparently these the adult tortoises, are an amazing

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Speaker 2: food source because of their immense size, and Darwin recounts

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Speaker 2: a story told to him by a mister Lawson, who

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Speaker 2: is an Englishman who is vice governor of the Charles

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Speaker 2: Island Colony, saying that some tortoises, when caught, required six

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Speaker 2: to eight men just to lift them off the ground

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Speaker 2: and would provide up to two hundred pounds of meat.

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Speaker 2: Darwin also later describes a strange operation performed by the hunters.

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Speaker 2: He says that you know they didn't always kill a tortoise.

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Speaker 2: He says that, well, the tortoises meat is used both

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Speaker 2: fresh and salted. The tortoises are also important for providing oil.

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Speaker 4: That's right, reptile lard.

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Speaker 2: And oil that I think could be used for food purposes,

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Speaker 2: but also for just like lamp purposes.

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Speaker 1: I believe yeah, it's said that in the old days,

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Speaker 1: the larger towns of the Galapagos would have their streets

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Speaker 1: would have been lit with tortoise oil.

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Speaker 2: Bizarre though, I guess we're more familiar with that from.

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Speaker 4: Like whale oil and stuff.

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Speaker 2: But yeah, so if a tortoise will not provide enough oil,

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Speaker 2: it is apparently not worth killing to the hunters. So

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Speaker 2: Darwin writes, quote, when a tortoise is caught, the man

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Speaker 2: makes a slit in the skin near its tail so

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Speaker 2: as to see inside its body whether the fat under

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Speaker 2: the dorsal plate is thick. If it's not, the animal

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Speaker 2: is liberated, and it is said to recover soon from

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Speaker 2: this strange operation. In order to secure the tortoise, it

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Speaker 2: is not sufficient to turn them like a turtle, for

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Speaker 2: they are often able to get.

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Speaker 4: On their legs again.

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Speaker 2: And I think this is something that will come up later,

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Speaker 2: because there are some situations where these tortoises often do

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Speaker 2: end up flipped on their backs, even under natural circumstances,

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Speaker 2: and they need to be able to flip back over

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Speaker 2: and get back to business.

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Speaker 1: I did not get to see that happen, thankfully. I

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Speaker 1: don't want to see a tortoise in distress.

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Speaker 2: No, we're not going to ask you the quiz from

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Speaker 2: the blade runner test. So what do these tortoises eat

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Speaker 2: to grow so big? Well, it turns out in reality,

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Speaker 2: they just they eat plants. These are entirely herbivorous creatures.

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Speaker 2: There are turtles and tortoises that eat other things, but

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Speaker 2: these tortoises are entirely plant eaters. And so especially in

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Speaker 2: the lowlands, especially the saddlebacked tortoises, will eat succulent cactus.

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Speaker 2: This is something Darwin identifies. He says they especially favor

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Speaker 2: the cactus if they live in the low and arid

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Speaker 2: parts of the islands where there is little or no water.

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Speaker 2: Of course the cactus becomes a principal water source, but

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Speaker 2: also they eat tree leaves and berries as well as

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Speaker 2: green lichen, and their diet somewhat depends on which species

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Speaker 2: they are and which part of the islands which microclimate

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Speaker 2: they inhabit. Like the ones that live higher up in

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Speaker 2: the highlands with more lush vegetation probably feed on more

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Speaker 2: leafy stuff, and the ones that live more in the

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Speaker 2: arid regions probably feed on more cactus.

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Speaker 1: Yeah, the ones I got to actually observe in the

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Speaker 1: wild as it were on San Cristobo on Santa Cruz Island.

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Speaker 1: They they were definitely eating the leafy green stuff. But

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Speaker 1: I got to see plenty of the cacti, which of

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Speaker 1: course have coexisted with the tortoises long enough that they

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Speaker 1: have particular adaptations, like they have been changed by cohabitation

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Speaker 1: with the tortoise as well. And the most remarkable of

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Speaker 1: these are the ones that they basically seem to grow

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Speaker 1: up like trees and then branch out because they're trying

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Speaker 1: to reach and reaching an optimal height at which they're

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Speaker 1: hopefully above the reach of the tortoise.

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Speaker 2: There is one type of cactus there's a great picture

395
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Speaker 2: of in this book by Creature in Laughlin I've been

396
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Speaker 2: talking about. It's called a candelabra cactus, and I thought

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Speaker 2: it was beautiful because the branches look to me like

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Speaker 2: giant green tarantula legs. They kind of have these lobes

399
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Speaker 2: that look like little hairy leg segments on a large spider.

400
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Speaker 1: Yeah. Yeah, And this is a nice picture too, because

401
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Speaker 1: you got a flamingo in there. I did get to

402
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Speaker 1: see a few flamingos on Seymour Island, I.

403
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Speaker 2: Believe, But the tortoises just generally seem to eat all

404
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Speaker 2: kinds of foods that would look to us quite hostile.

405
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Speaker 2: So of course the ones in the lowlands are going

406
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Speaker 2: to eat a lot of cactus, but they also apparently

407
00:23:18,320 --> 00:23:21,520
Speaker 2: eat plenty of poison apple or men's in illo, which

408
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Speaker 2: is toxic. It has a sap that is poisonous to

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Speaker 2: other creatures, and I think it can cause blistering if

410
00:23:29,920 --> 00:23:33,440
Speaker 2: you touch it. But apparently the tortoises just chow down

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Speaker 2: on this stuff, doesn't bother them.

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Speaker 1: Yeah. On San Cristobo Island, the area where we were

413
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Speaker 1: encountering the tortoises, they had signs everywhere, do not touch

414
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Speaker 1: the apples. Do certainly do not eat the apples. Leave

415
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Speaker 1: this to the tortoises.

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Speaker 2: Now, coming back to Darwin's writing on the tortoises, he

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Speaker 2: also observes their relationship with water. He says, they are notable,

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Speaker 2: of course for their ability to survive without water for

419
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Speaker 2: a very long time. But when they get out access

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Speaker 2: to water, they go hog wild. They love it, the

421
00:24:03,920 --> 00:24:06,240
Speaker 2: spring water and the mud puddles. They'll just get in

422
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Speaker 2: there and settle in, sometimes for days at a.

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Speaker 4: Time, and when.

424
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Speaker 2: They're drinking they will just gulp huge mouthfuls of water

425
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Speaker 2: for a long time. And Darwin even this leads into

426
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Speaker 2: him writing a really bizarre anecdote that I had to share.

427
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Speaker 2: So he says, quote for some time after a visit

428
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Speaker 2: to the springs, their urinary bladders are distended with fluid

429
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Speaker 2: which is said to gradually which is said to gradually

430
00:24:32,359 --> 00:24:36,560
Speaker 2: decrease in volume and to become less pure. The inhabitants,

431
00:24:36,600 --> 00:24:39,320
Speaker 2: when walking in the lower district and overcome with thirst,

432
00:24:39,359 --> 00:24:42,880
Speaker 2: often take advantage of this circumstance and drink the contents

433
00:24:42,920 --> 00:24:46,600
Speaker 2: of the bladder if full. In one tortoise I saw killed,

434
00:24:46,640 --> 00:24:49,880
Speaker 2: the fluid was quite limpid and had only a very

435
00:24:49,920 --> 00:24:54,240
Speaker 2: slightly bitter taste. The inhabitants, however, always first drink the

436
00:24:54,280 --> 00:24:57,480
Speaker 2: water in the pericardium, which is the membrane of belief

437
00:24:57,520 --> 00:25:01,439
Speaker 2: that surrounding the heart tissue, which described as being best.

438
00:25:01,800 --> 00:25:05,520
Speaker 2: So that's right, drinking the water from a tortoise's heart

439
00:25:05,680 --> 00:25:09,120
Speaker 2: or from a tortoise's bladder. And Darwin tasted the tortoise

440
00:25:09,119 --> 00:25:09,760
Speaker 2: bladder water.

441
00:25:10,720 --> 00:25:14,280
Speaker 1: I guess I should be happy for this, that they're

442
00:25:14,359 --> 00:25:17,960
Speaker 1: using all parts of the tortoise conceivably in doing this.

443
00:25:18,080 --> 00:25:21,960
Speaker 1: But of course this is still kind of sad to imagine. Yeah,

444
00:25:22,240 --> 00:25:26,320
Speaker 1: but also from just a purely anatomical level, this is

445
00:25:26,359 --> 00:25:27,120
Speaker 1: of course amazing.

446
00:25:27,720 --> 00:25:31,639
Speaker 2: Now, Darwin goes on to talk about how impressed he

447
00:25:31,760 --> 00:25:35,200
Speaker 2: is by the long determined journeys that some of these

448
00:25:35,240 --> 00:25:40,360
Speaker 2: tortoises make between He believes what the point of these

449
00:25:40,440 --> 00:25:44,120
Speaker 2: journeys is is between highland water sources and usual breeding

450
00:25:44,160 --> 00:25:47,160
Speaker 2: grounds in the lower districts. I don't know if that

451
00:25:47,200 --> 00:25:49,719
Speaker 2: holds up as the main reason for these journeys today,

452
00:25:50,240 --> 00:25:53,920
Speaker 2: though I do think some of these tortoises do make

453
00:25:54,000 --> 00:25:57,159
Speaker 2: journeys between the highlands and the lowlands for the purpose

454
00:25:57,160 --> 00:26:00,800
Speaker 2: of depositing eggs the females do after mating season. But

455
00:26:00,840 --> 00:26:02,720
Speaker 2: there are also journeys I think having to do with

456
00:26:03,119 --> 00:26:06,080
Speaker 2: food resources in the different seasons and so forth. But anyway,

457
00:26:06,400 --> 00:26:09,520
Speaker 2: Darwin says, you know, although the tortoises are pretty slow

458
00:26:09,560 --> 00:26:12,040
Speaker 2: in their movements, you would be surprised how much ground

459
00:26:12,040 --> 00:26:15,760
Speaker 2: they cover over time due to sheer determination. He estimates

460
00:26:15,800 --> 00:26:18,280
Speaker 2: that they're going to move sixty yards in ten minutes,

461
00:26:18,640 --> 00:26:21,119
Speaker 2: which is three hundred and sixty yards in an hour,

462
00:26:21,520 --> 00:26:22,960
Speaker 2: or about four miles a day.

463
00:26:23,680 --> 00:26:27,080
Speaker 1: Yeah, it's pretty remarkable, and of course nowadays of course

464
00:26:27,119 --> 00:26:29,760
Speaker 1: that everything has been shifted around a bit. You know,

465
00:26:29,800 --> 00:26:33,000
Speaker 1: all these invasive species, not only the such harmful invasive

466
00:26:33,000 --> 00:26:38,280
Speaker 1: species as pigs and goats that were introduced and then

467
00:26:38,320 --> 00:26:41,000
Speaker 1: their populations have been dealt with to varying degrees. But

468
00:26:41,040 --> 00:26:43,520
Speaker 1: you also have, of course, have plants to think about,

469
00:26:44,320 --> 00:26:47,440
Speaker 1: and so in some cases you have things like berries

470
00:26:47,480 --> 00:26:50,800
Speaker 1: that are now grown in the Galapagos and may occur

471
00:26:50,880 --> 00:26:54,120
Speaker 1: wild in some cases, and of course the tortoises love

472
00:26:54,160 --> 00:26:56,720
Speaker 1: those even though they are not native, and so you

473
00:26:56,800 --> 00:27:00,360
Speaker 1: may see that interfere with their movements. So that but yeah,

474
00:27:00,520 --> 00:27:05,359
Speaker 1: basically through modern conservation and through modern tracking technology, you

475
00:27:05,400 --> 00:27:09,120
Speaker 1: can actually see all of these tortoise movements plotted out

476
00:27:09,200 --> 00:27:13,679
Speaker 1: on maps and it's quite impressive. I think they are

477
00:27:13,720 --> 00:27:17,000
Speaker 1: movements in these cases help illustrate why they're so crucial

478
00:27:17,080 --> 00:27:20,280
Speaker 1: for the island ecosystem that they thrive in. They eat

479
00:27:20,440 --> 00:27:23,320
Speaker 1: so much and while they're slow, they do cover a

480
00:27:23,359 --> 00:27:27,960
Speaker 1: lot of ground and defecate to spread speeds spread seeds rather,

481
00:27:28,480 --> 00:27:30,520
Speaker 1: and this is very much in line with other megafona

482
00:27:30,520 --> 00:27:34,800
Speaker 1: that you encounter in other ecosystems as well as the

483
00:27:34,880 --> 00:27:37,440
Speaker 1: remember if you think back to our episode on or

484
00:27:37,480 --> 00:27:41,120
Speaker 1: episodes on the giant moa bird, which of course is extinct,

485
00:27:41,440 --> 00:27:44,439
Speaker 1: but would have we still see like the footprint of

486
00:27:44,520 --> 00:27:49,679
Speaker 1: their ecological importance in the areas that they occupied, because

487
00:27:49,720 --> 00:27:53,480
Speaker 1: they were vital for consuming plants and then spreading those

488
00:27:53,480 --> 00:27:54,639
Speaker 1: seeds through defecation.

489
00:27:55,240 --> 00:27:57,959
Speaker 2: Yeah, there is a great passage in the book by

490
00:27:58,000 --> 00:28:00,760
Speaker 2: Creature and Laughlin where they talk about the importance of

491
00:28:00,800 --> 00:28:05,760
Speaker 2: the tortoise in spreading a type a species of wild

492
00:28:05,840 --> 00:28:11,200
Speaker 2: Galapagos tomato plant, which apparently it only the seeds only

493
00:28:11,240 --> 00:28:14,600
Speaker 2: germinate under very specific conditions, such as being exposed to

494
00:28:15,200 --> 00:28:17,080
Speaker 2: acid for a long period of time.

495
00:28:17,160 --> 00:28:18,720
Speaker 4: Now, how does that happen, Well.

496
00:28:18,600 --> 00:28:21,560
Speaker 2: It happens in the digestive system of the tortoise. So

497
00:28:21,680 --> 00:28:25,000
Speaker 2: like they take this in, the seed gets exposed to

498
00:28:25,040 --> 00:28:28,840
Speaker 2: the acid within the digestive juices, and then it gets

499
00:28:29,040 --> 00:28:31,800
Speaker 2: it travels with the tortoise a long ways away from

500
00:28:31,920 --> 00:28:35,959
Speaker 2: its original location, so that's also good for dispersal. And

501
00:28:36,000 --> 00:28:38,560
Speaker 2: then once the tortoise poops it out, it of course

502
00:28:38,600 --> 00:28:41,640
Speaker 2: has a bunch of nutritious fecal matter surrounding it to

503
00:28:41,720 --> 00:28:42,320
Speaker 2: help it grow.

504
00:28:42,880 --> 00:28:45,840
Speaker 1: Yeah, yeah, I've got I did get to poke some

505
00:28:46,640 --> 00:28:48,800
Speaker 1: tortoise dung with a stick. My son and I did,

506
00:28:48,840 --> 00:28:51,600
Speaker 1: and we got to look all in there. It's, you know,

507
00:28:51,680 --> 00:28:56,040
Speaker 1: quite fascinating. I think some stats would really help drive

508
00:28:56,080 --> 00:28:58,280
Speaker 1: home though, why the tortoise is so great at this.

509
00:28:59,160 --> 00:29:02,600
Speaker 1: And I got these from Seed Dispersal by Galapagos Tortoises

510
00:29:02,600 --> 00:29:05,840
Speaker 1: by Blake at All, published in the Journal of Biogeography

511
00:29:05,880 --> 00:29:09,480
Speaker 1: from twenty twelve. So, in this particular survey, the researchers

512
00:29:09,480 --> 00:29:12,000
Speaker 1: looked at one hundred and twenty fresh dung piles in

513
00:29:12,080 --> 00:29:17,040
Speaker 1: both agricultural and national parkland. They found seeds from more

514
00:29:17,080 --> 00:29:20,040
Speaker 1: than forty five plant species in these dung piles, eleven

515
00:29:20,040 --> 00:29:22,720
Speaker 1: of which were from introduced species, you know, like various

516
00:29:22,760 --> 00:29:27,400
Speaker 1: berries and whatnot. A per tortoise average of four hundred

517
00:29:27,400 --> 00:29:30,680
Speaker 1: and sixty four seeds and two point eight species per

518
00:29:30,800 --> 00:29:33,840
Speaker 1: dung pile was detected. Now, this is where it gets

519
00:29:33,920 --> 00:29:36,280
Speaker 1: kind of interesting, because, okay, we've already established that, yes,

520
00:29:36,320 --> 00:29:39,480
Speaker 1: they eat a lot, they travel farther than you might think,

521
00:29:40,000 --> 00:29:43,280
Speaker 1: But how long does it take for them to process

522
00:29:43,320 --> 00:29:48,360
Speaker 1: their food? Things go a little slower with the Galapagos tortoises.

523
00:29:48,720 --> 00:29:54,360
Speaker 1: The mean digesta retention time for a tortoise is twelve days,

524
00:29:54,640 --> 00:29:58,440
Speaker 1: but twenty eight day retention times have been reported, so

525
00:29:59,520 --> 00:30:01,680
Speaker 1: that's the time time it takes for the food that

526
00:30:01,680 --> 00:30:05,440
Speaker 1: they've consumed to process through their body and become dung, so.

527
00:30:05,360 --> 00:30:07,320
Speaker 2: They can really cover some ground in that time.

528
00:30:07,800 --> 00:30:10,760
Speaker 1: Yeah. During that time, according to this paper, the tortoise

529
00:30:10,800 --> 00:30:14,200
Speaker 1: may travel between three hundred and ninety four and four

530
00:30:14,280 --> 00:30:17,200
Speaker 1: three hundred and fifty five meters on the high end,

531
00:30:17,360 --> 00:30:20,160
Speaker 1: that's two point seven miles or four point three kilometers.

532
00:30:20,720 --> 00:30:22,640
Speaker 2: So you can see how these tortoises would play an

533
00:30:22,640 --> 00:30:26,880
Speaker 2: incredibly important role in helping the reproduction and dispersal of

534
00:30:27,160 --> 00:30:27,960
Speaker 2: local flora.

535
00:30:28,480 --> 00:30:31,880
Speaker 1: Yeah. Absolutely. I mean, as with any species, they don't

536
00:30:31,920 --> 00:30:35,080
Speaker 1: they're not existing in isolation in their ecosystem. They have

537
00:30:35,160 --> 00:30:39,080
Speaker 1: a roll, they have a place in it. And if

538
00:30:39,800 --> 00:30:42,120
Speaker 1: you disrupt them, if you disrupt their numbers, or in

539
00:30:42,360 --> 00:30:46,320
Speaker 1: the very worst case scenarios, if their extinction is brought about,

540
00:30:46,920 --> 00:30:50,360
Speaker 1: then there is there's something missing. There's a you end

541
00:30:50,440 --> 00:30:54,440
Speaker 1: up pulling the carpet out from everything, and unlike with

542
00:30:54,760 --> 00:30:57,120
Speaker 1: the parlor trick, all the plates and the dishes are

543
00:30:57,120 --> 00:30:59,000
Speaker 1: not necessarily going to stay standing up.

544
00:31:08,040 --> 00:31:11,200
Speaker 2: Now we've been talking about a lot of the predation

545
00:31:11,560 --> 00:31:15,800
Speaker 2: and hunting of these tortoises. But barring that, how do

546
00:31:15,960 --> 00:31:16,880
Speaker 2: tortoises die?

547
00:31:17,040 --> 00:31:17,840
Speaker 4: What happens?

548
00:31:18,840 --> 00:31:21,920
Speaker 2: Well, Darwin writes, quote the young tortoises as soon as

549
00:31:21,960 --> 00:31:24,560
Speaker 2: they are hatched, fall preying great numbers to the carryon

550
00:31:24,640 --> 00:31:28,200
Speaker 2: feeding buzzard. I think that would actually be referring probably

551
00:31:28,240 --> 00:31:31,480
Speaker 2: to the Galapago's hawk, unless he's talking about some other

552
00:31:32,120 --> 00:31:37,240
Speaker 2: species that came in after humans arrived. But and Darwin

553
00:31:37,280 --> 00:31:40,880
Speaker 2: goes on, the old ones seemed to die generally from accidents,

554
00:31:41,280 --> 00:31:44,840
Speaker 2: as from falling down precipices. At least several of the

555
00:31:44,840 --> 00:31:48,400
Speaker 2: inhabitants told me that they never found one dead without

556
00:31:48,440 --> 00:31:51,200
Speaker 2: some evident cause, which, oh, that kind of gave me

557
00:31:51,240 --> 00:31:51,600
Speaker 2: a shiver.

558
00:31:53,600 --> 00:31:56,960
Speaker 1: Yeah, yeah, I mean, it's just impressive how long they live.

559
00:31:58,040 --> 00:32:00,680
Speaker 1: That and I did the first point about P's worth

560
00:32:00,680 --> 00:32:03,040
Speaker 1: pointing out that the tortoise sanctuaries that are up and

561
00:32:03,080 --> 00:32:05,600
Speaker 1: running now they care for the little ones to protect

562
00:32:05,640 --> 00:32:08,240
Speaker 1: them from you know, not only the hawk, but also

563
00:32:08,280 --> 00:32:12,400
Speaker 1: all these introduced species that may be about once they

564
00:32:12,680 --> 00:32:15,400
Speaker 1: get big enough. Though, Yeah, there's only really three ways

565
00:32:15,400 --> 00:32:21,160
Speaker 1: they're going to die old age eventually, accident, vehicular especially

566
00:32:21,280 --> 00:32:25,320
Speaker 1: of course being the main threat, though on the Galapico

567
00:32:25,320 --> 00:32:29,360
Speaker 1: sidelands today a lot of you know, laws and messaging

568
00:32:29,840 --> 00:32:32,120
Speaker 1: have been put in place to prevent this from occurring.

569
00:32:32,160 --> 00:32:34,760
Speaker 1: And then of course in the past human hunting was

570
00:32:34,920 --> 00:32:35,480
Speaker 1: the big thing.

571
00:32:36,080 --> 00:32:38,120
Speaker 2: Now you mentioned they can die of old age, of

572
00:32:38,200 --> 00:32:39,880
Speaker 2: course they do, but that can take.

573
00:32:39,760 --> 00:32:41,000
Speaker 4: A good long while.

574
00:32:41,440 --> 00:32:44,120
Speaker 2: I was reading about this in a Creature in Laughlin

575
00:32:44,760 --> 00:32:48,240
Speaker 2: and they say that it's possible, though we have no

576
00:32:48,320 --> 00:32:50,720
Speaker 2: way to know for sure, that there may be tortoises

577
00:32:50,760 --> 00:32:54,240
Speaker 2: still alive on the islands that were present when Darwin

578
00:32:54,320 --> 00:32:58,520
Speaker 2: visited in eighteen thirty five, and a Galopago's tortoise named

579
00:32:58,520 --> 00:33:01,000
Speaker 2: Harriet lived to an estimated age of one hundred and

580
00:33:01,040 --> 00:33:04,880
Speaker 2: seventy five before she died in an Australian zoo in

581
00:33:04,920 --> 00:33:07,400
Speaker 2: two thousand and six, so they can live a long

582
00:33:07,640 --> 00:33:08,320
Speaker 2: long time.

583
00:33:09,240 --> 00:33:11,600
Speaker 1: Yeah, I was doing some crunching on this as well.

584
00:33:11,640 --> 00:33:13,200
Speaker 1: I think one of the sources I was looking at

585
00:33:13,840 --> 00:33:15,920
Speaker 1: had listed like one hundred and seventy one years as

586
00:33:15,960 --> 00:33:20,840
Speaker 1: being one of the oldest stage is known for the tortoises.

587
00:33:20,840 --> 00:33:22,480
Speaker 1: And even if you're just going to go with that,

588
00:33:23,400 --> 00:33:25,840
Speaker 1: if you consider the idea that you have a tortoise

589
00:33:26,320 --> 00:33:29,520
Speaker 1: born in eighteen thirty five when Darwin is visiting, if

590
00:33:29,520 --> 00:33:31,480
Speaker 1: it lived one hundred and seventy one years, it would

591
00:33:31,520 --> 00:33:34,360
Speaker 1: live to the year two thousand and six. Wow, which

592
00:33:34,400 --> 00:33:36,960
Speaker 1: is just crazy to think about the idea that just

593
00:33:37,160 --> 00:33:41,400
Speaker 1: one tortoise lifetime would bridge our time to the time

594
00:33:41,440 --> 00:33:45,760
Speaker 1: of Darwin, and that a single tortoise lifetime could encompass

595
00:33:45,800 --> 00:33:50,720
Speaker 1: basically the two worst centuries of the impact of humanity

596
00:33:51,080 --> 00:33:54,560
Speaker 1: on Galapago's tortoise numbers as well. Now, again not to

597
00:33:54,560 --> 00:33:58,680
Speaker 1: come back too much to the horrors of human tortoise interaction,

598
00:33:58,720 --> 00:34:01,000
Speaker 1: but yeah, there are these accounts read too of like

599
00:34:01,360 --> 00:34:05,960
Speaker 1: times when roads to various villages were just lined with

600
00:34:06,640 --> 00:34:11,320
Speaker 1: like the bones or the shells of these creatures. It

601
00:34:11,480 --> 00:34:13,960
Speaker 1: was it was a rough time to be a Galapagos tortoise.

602
00:34:14,480 --> 00:34:18,200
Speaker 2: Yes, no, I now I think it's worth talking about

603
00:34:18,719 --> 00:34:23,080
Speaker 2: Galapagos tortoise mating and reproduction, which there's some interesting stuff.

604
00:34:24,000 --> 00:34:27,000
Speaker 2: For one thing I was reading about Maybe we can

605
00:34:27,040 --> 00:34:29,280
Speaker 2: get to the actual mating in a minute, But first

606
00:34:29,320 --> 00:34:34,040
Speaker 2: I was reading a section in Creature in Laughlin about

607
00:34:34,160 --> 00:34:37,759
Speaker 2: the nests and egg laying of the Glopagos tortoise. So

608
00:34:38,040 --> 00:34:42,720
Speaker 2: mating season typically occurs during the rainy season, and after

609
00:34:42,800 --> 00:34:47,360
Speaker 2: having mated, a female tortoise will generally travel toward the

610
00:34:47,440 --> 00:34:50,720
Speaker 2: arid lowlands to build a nest. Darwin has a section

611
00:34:50,760 --> 00:34:53,560
Speaker 2: about this where he correctly observes that they will seek

612
00:34:53,560 --> 00:34:56,560
Speaker 2: out arid sandy soil to dig a nest in, but

613
00:34:56,600 --> 00:34:58,840
Speaker 2: then he says others. He says, sometimes they will just

614
00:34:58,920 --> 00:35:01,680
Speaker 2: drop their eggs where like in a precipice, like in

615
00:35:01,719 --> 00:35:04,600
Speaker 2: a crevice in the rocks. I didn't find any other

616
00:35:04,880 --> 00:35:07,120
Speaker 2: evidence of that, so maybe that was true when he

617
00:35:07,160 --> 00:35:09,960
Speaker 2: was there, but I'm not aware of other evidence for

618
00:35:10,000 --> 00:35:13,040
Speaker 2: that other than what Darwin says. But generally what they

619
00:35:13,040 --> 00:35:16,680
Speaker 2: do is they're going to dig down in the arid regions. Now,

620
00:35:17,360 --> 00:35:19,840
Speaker 2: for the saddleback tortoises, which tend to live more in

621
00:35:19,880 --> 00:35:21,960
Speaker 2: the lowlands, this is not much of a trip. But

622
00:35:22,000 --> 00:35:24,479
Speaker 2: for the domed tortoises it can be a really great

623
00:35:24,520 --> 00:35:27,719
Speaker 2: journey down from the highlands into the place where they're going.

624
00:35:27,640 --> 00:35:28,920
Speaker 4: To lay the eggs.

625
00:35:29,560 --> 00:35:32,680
Speaker 2: And the eggs are laid sometime between June and December.

626
00:35:32,920 --> 00:35:36,440
Speaker 2: A clutch can contain anywhere from like two to twenty eggs.

627
00:35:36,840 --> 00:35:39,319
Speaker 2: The eggs are sort of billiard ball sized or maybe

628
00:35:39,360 --> 00:35:43,279
Speaker 2: a little bit larger. And the nest building process is

629
00:35:43,360 --> 00:35:46,080
Speaker 2: what interested me because apparently it involves a good bit

630
00:35:46,120 --> 00:35:49,880
Speaker 2: of pa. So the tortoise will find a spot in

631
00:35:49,960 --> 00:35:52,400
Speaker 2: the soil and she will dig a hole about thirty

632
00:35:52,400 --> 00:35:55,720
Speaker 2: centimeters deep, scooping the earth out with her hind legs,

633
00:35:56,239 --> 00:35:59,359
Speaker 2: and this is an involved process that can take up

634
00:35:59,360 --> 00:36:02,840
Speaker 2: to about twelve hours, and the tortoise will often urinate

635
00:36:02,960 --> 00:36:05,640
Speaker 2: on the soil in order to soften it for digging.

636
00:36:06,239 --> 00:36:08,840
Speaker 2: But the mother tortoise, after she lays her eggs in

637
00:36:08,840 --> 00:36:11,239
Speaker 2: the hole and covers it up, then also peas on

638
00:36:11,320 --> 00:36:14,760
Speaker 2: the soil again to form a kind of cement layer

639
00:36:14,880 --> 00:36:15,200
Speaker 2: in it.

640
00:36:15,880 --> 00:36:19,799
Speaker 1: This is interesting. We've discussed a number of different nest

641
00:36:19,880 --> 00:36:23,480
Speaker 1: building egg laying scenarios over the years, but I don't

642
00:36:23,480 --> 00:36:25,320
Speaker 1: remember one that was so urine intensive.

643
00:36:25,719 --> 00:36:28,400
Speaker 2: Yeah, there may be other species that do pie cement,

644
00:36:28,600 --> 00:36:31,480
Speaker 2: but this is the first time I remember reading about this.

645
00:36:32,400 --> 00:36:35,640
Speaker 2: So anyway, the eggs incubate in the cemented earth for

646
00:36:35,680 --> 00:36:38,440
Speaker 2: like four to eight months, where the sex of the

647
00:36:38,480 --> 00:36:42,400
Speaker 2: hatchling is ultimately determined by the temperature which the egg incubates.

648
00:36:42,400 --> 00:36:45,759
Speaker 2: That's kind of interesting. It's not chromosomally determined as it

649
00:36:45,800 --> 00:36:49,640
Speaker 2: is for some other animals, and so afterwards they dig

650
00:36:49,680 --> 00:36:51,920
Speaker 2: their way out of the nest to begin their lives,

651
00:36:52,040 --> 00:36:54,520
Speaker 2: and of course this is the most vulnerable time for

652
00:36:54,600 --> 00:36:58,919
Speaker 2: a Galapagos tortoise when they're a hatchling, but the ones

653
00:36:58,960 --> 00:37:02,160
Speaker 2: that survived make it out. They find food, they avoid predators,

654
00:37:02,160 --> 00:37:04,600
Speaker 2: and they eventually grow up, though apparently the growing up

655
00:37:04,640 --> 00:37:07,200
Speaker 2: also takes a good bit of time. The tortoises do

656
00:37:07,280 --> 00:37:11,359
Speaker 2: everything pretty slow, including reaching maturity. I've read that they

657
00:37:11,480 --> 00:37:14,919
Speaker 2: don't reach sexual maturity until several decades later.

658
00:37:15,800 --> 00:37:20,360
Speaker 1: The mating itself is also kind of interesting because they

659
00:37:20,480 --> 00:37:23,560
Speaker 1: basically consists of the males chasing the females around until

660
00:37:23,560 --> 00:37:27,719
Speaker 1: they can corner them. But then there's also, given these

661
00:37:27,719 --> 00:37:32,000
Speaker 1: are large shelled creatures, the male's shell has like an

662
00:37:32,000 --> 00:37:35,080
Speaker 1: indention on the bottom that allows for it to mount

663
00:37:35,120 --> 00:37:39,160
Speaker 1: the female, because otherwise, unless there was some arrangement of

664
00:37:39,200 --> 00:37:42,200
Speaker 1: the shells in this capacity, that they would not be compatible.

665
00:37:42,880 --> 00:37:45,800
Speaker 2: Right, And there was also a fact I came across

666
00:37:45,840 --> 00:37:48,000
Speaker 2: that I thought was funny. In this book, they talk

667
00:37:48,080 --> 00:37:51,359
Speaker 2: about how the larger size of the Glopagos tortoise can

668
00:37:51,400 --> 00:37:55,120
Speaker 2: make the physical active mating sometimes kind of cumbersome and laborious,

669
00:37:55,680 --> 00:37:59,359
Speaker 2: and the authors note that quote, males often slide off,

670
00:38:00,000 --> 00:38:03,640
Speaker 2: even inadvertently, landing upside down, at which point they must

671
00:38:03,760 --> 00:38:06,279
Speaker 2: right themselves and try again, which I don't know if

672
00:38:06,320 --> 00:38:08,680
Speaker 2: it's juvenile that I found that funny, but I did.

673
00:38:09,040 --> 00:38:13,440
Speaker 2: The authors also note that the male tortoises sometimes get confused.

674
00:38:13,560 --> 00:38:15,680
Speaker 2: For example, they try to mate with large rocks.

675
00:38:17,520 --> 00:38:19,919
Speaker 1: Well, that's just, in and of itself funny. We can't

676
00:38:19,920 --> 00:38:20,640
Speaker 1: help but laugh at that.

677
00:38:21,320 --> 00:38:25,440
Speaker 2: But there's also surprising. For these very slow moving animals,

678
00:38:25,480 --> 00:38:29,920
Speaker 2: there is some surprisingly fierce competition between males for access

679
00:38:29,960 --> 00:38:33,400
Speaker 2: to mates, and Darwin notes this. He says, during breeding season,

680
00:38:33,480 --> 00:38:35,640
Speaker 2: you can hear the males emit what he calls a

681
00:38:35,800 --> 00:38:41,000
Speaker 2: horse roar. And I think this roar is probably indicative

682
00:38:41,040 --> 00:38:44,239
Speaker 2: of male on male competition, which sometimes leads to these

683
00:38:44,360 --> 00:38:47,040
Speaker 2: mock fights where they will raise their necks up at

684
00:38:47,040 --> 00:38:49,920
Speaker 2: each other. Rob, I think you actually maybe saw one

685
00:38:49,960 --> 00:38:50,839
Speaker 2: of these going on.

686
00:38:51,440 --> 00:38:54,480
Speaker 1: Yes, I got to see this happen, and I actually

687
00:38:54,719 --> 00:38:57,560
Speaker 1: got to film it. I was able to my wife

688
00:38:57,600 --> 00:38:59,480
Speaker 1: was like, quick, get your camera out, make sure you're

689
00:38:59,480 --> 00:39:02,280
Speaker 1: getting this. So I did. Yeah, it's amazing to watch

690
00:39:02,320 --> 00:39:06,120
Speaker 1: because you'll have these two lumbering giants that are kind

691
00:39:06,120 --> 00:39:08,440
Speaker 1: of on a collision course with each other, and you're like,

692
00:39:08,440 --> 00:39:10,520
Speaker 1: what's going to happen, what's going to happen? And then

693
00:39:10,560 --> 00:39:13,560
Speaker 1: as they get closer, they'll both rear their heads up

694
00:39:14,080 --> 00:39:16,880
Speaker 1: and they'll have this showdown that doesn't it does not

695
00:39:16,920 --> 00:39:19,440
Speaker 1: come to blows or bites or anything like that, but

696
00:39:19,520 --> 00:39:21,959
Speaker 1: it is a competition to see who to determine who

697
00:39:22,000 --> 00:39:25,680
Speaker 1: is the tallest and the tallest tortoise, who had the

698
00:39:25,680 --> 00:39:28,520
Speaker 1: one that can raise its head up the highest, he's

699
00:39:28,560 --> 00:39:31,960
Speaker 1: the winner, and the other one accepts defeat and carries on.

700
00:39:32,760 --> 00:39:35,160
Speaker 1: And that's as violent as it seems to get. But

701
00:39:35,239 --> 00:39:38,880
Speaker 1: it's spectacular to watch. And this was the finest nature

702
00:39:38,920 --> 00:39:42,160
Speaker 1: footage I have ever captured or will ever capture.

703
00:39:42,800 --> 00:39:44,840
Speaker 2: Now, one last thing I wanted to read from Darwin

704
00:39:44,920 --> 00:39:47,640
Speaker 2: here where he's talking about the tortoise's reaction to humans.

705
00:39:47,680 --> 00:39:50,840
Speaker 2: This is another infamous section from the Voyage of the

706
00:39:50,840 --> 00:39:55,440
Speaker 2: Beagle chapter. Darwin says, I was always amused when overtaking

707
00:39:55,480 --> 00:39:58,520
Speaker 2: one of these great monsters as it was quietly pacing along,

708
00:39:58,880 --> 00:40:01,640
Speaker 2: to see how suddenly the instant I passed it would

709
00:40:01,719 --> 00:40:05,080
Speaker 2: draw in its head and legs and uttering a deep hiss,

710
00:40:05,120 --> 00:40:07,440
Speaker 2: fall to the ground with a heavy sound, as if

711
00:40:07,520 --> 00:40:12,160
Speaker 2: struck dead. I frequently got on their backs and then

712
00:40:12,239 --> 00:40:14,920
Speaker 2: giving a few wraps on the hinder part of the shells,

713
00:40:15,200 --> 00:40:17,839
Speaker 2: they would rise up and walk away, but I found

714
00:40:17,840 --> 00:40:19,680
Speaker 2: it very difficult to keep my balance.

715
00:40:20,440 --> 00:40:24,760
Speaker 1: Oh, Charles, no doing, Why are you riding a tortoise?

716
00:40:26,160 --> 00:40:30,319
Speaker 1: I mean it is kind of I mean it based

717
00:40:30,320 --> 00:40:33,080
Speaker 1: on this account, the tortoise is doing exactly what you

718
00:40:33,120 --> 00:40:35,200
Speaker 1: know I observed, and all these sources say they do

719
00:40:35,400 --> 00:40:37,880
Speaker 1: if someone gets too close or something gets too close.

720
00:40:38,080 --> 00:40:40,960
Speaker 1: But it is kind of interesting this added detail that

721
00:40:41,080 --> 00:40:44,200
Speaker 1: apparently eventually the tortoise is like, Okay, I guess this

722
00:40:44,200 --> 00:40:47,280
Speaker 1: weird British man is not going away. I have things

723
00:40:47,280 --> 00:40:49,719
Speaker 1: to do in places to be I'm just going to

724
00:40:49,800 --> 00:40:52,239
Speaker 1: start walking around with him on there and maybe I

725
00:40:52,239 --> 00:40:53,319
Speaker 1: can sort of shake him off.

726
00:40:53,800 --> 00:40:57,320
Speaker 2: Yeah, and this is actually not an isolated report. Again,

727
00:40:57,400 --> 00:41:00,439
Speaker 2: we are not recommending riding the tortoises, and other other

728
00:41:00,520 --> 00:41:02,600
Speaker 2: people talk about how well you can get on their

729
00:41:02,640 --> 00:41:04,960
Speaker 2: backs and ride them and they'll just go about their business.

730
00:41:05,000 --> 00:41:08,759
Speaker 2: And this is apparently a common occurrence. There was a

731
00:41:08,760 --> 00:41:10,040
Speaker 2: common occurrence.

732
00:41:09,600 --> 00:41:10,200
Speaker 4: Back in the day.

733
00:41:10,600 --> 00:41:12,600
Speaker 2: Sometimes they say, you can get two people on one

734
00:41:12,640 --> 00:41:15,200
Speaker 2: of these tortoise shells and just ride them and they'll

735
00:41:15,239 --> 00:41:18,880
Speaker 2: do their thing, like you know, they don't seem they

736
00:41:18,880 --> 00:41:21,200
Speaker 2: don't seem bothered. Now, I'm sure that puts extra strain

737
00:41:21,320 --> 00:41:23,520
Speaker 2: on their muscles and their energy requirements and all that.

738
00:41:23,560 --> 00:41:26,400
Speaker 2: So it's not like okay to do. But just showing

739
00:41:26,440 --> 00:41:29,120
Speaker 2: the strength of the tortoise and how powerful and huge

740
00:41:29,200 --> 00:41:32,160
Speaker 2: this animal is that it could just continue on its

741
00:41:32,160 --> 00:41:35,080
Speaker 2: way trying to graze with like multiple humans riding on

742
00:41:35,120 --> 00:41:35,560
Speaker 2: its back.

743
00:41:36,120 --> 00:41:43,239
Speaker 1: Oh, poor creatures. Yeah, again, do not attempt to don't

744
00:41:43,280 --> 00:41:45,279
Speaker 1: do not get close to the tortoises, and do not

745
00:41:45,480 --> 00:41:48,040
Speaker 1: ride them. Now, we have a fair amount of variety

746
00:41:48,080 --> 00:41:51,439
Speaker 1: with the Glapygos tortoises that they're all of the genus Chellinitis,

747
00:41:52,080 --> 00:41:57,160
Speaker 1: and you get into some discussion about the different varieties

748
00:41:57,239 --> 00:42:01,799
Speaker 1: like the exact variety count. And then we have two

749
00:42:01,880 --> 00:42:08,040
Speaker 1: that are definitely extinct. There's the Floriana Island subspecies that's

750
00:42:08,040 --> 00:42:10,319
Speaker 1: thought to have been hunted to extinction by I think

751
00:42:10,400 --> 00:42:13,360
Speaker 1: eighteen fifty when Darwin visited. This is I believe the

752
00:42:13,400 --> 00:42:17,240
Speaker 1: one where he only describes seeing their bones. The Pina

753
00:42:17,360 --> 00:42:21,000
Speaker 1: Island species is extinct as of twenty twelve, with the

754
00:42:21,040 --> 00:42:23,440
Speaker 1: death of Lonesome George, who was of course famous for

755
00:42:23,480 --> 00:42:28,520
Speaker 1: being the last of his variety. He died and that

756
00:42:29,000 --> 00:42:31,520
Speaker 1: was seemingly it for this variety of tortoise.

757
00:42:31,920 --> 00:42:32,160
Speaker 4: Yeah.

758
00:42:32,200 --> 00:42:37,920
Speaker 2: I've read that there are either twelve or thirteen extant species.

759
00:42:38,400 --> 00:42:51,680
Speaker 1: Yeah. So, coming back to the challenges that tortoises faced

760
00:42:51,760 --> 00:42:55,759
Speaker 1: during the age of humans, we've thoroughly discussed. I think

761
00:42:55,800 --> 00:42:59,520
Speaker 1: the human hunting and human harvesting of tortoises, at least

762
00:42:59,560 --> 00:43:02,000
Speaker 1: for our purpose, is here. But of course there are

763
00:43:02,040 --> 00:43:07,200
Speaker 1: all these invasive species that humans introduced, and while we

764
00:43:07,239 --> 00:43:10,520
Speaker 1: are dealing with cases in some cases where you'll have

765
00:43:10,600 --> 00:43:14,839
Speaker 1: animals directly going after young tortoises, there are also other

766
00:43:14,920 --> 00:43:19,440
Speaker 1: ways that these creatures were harmful and are and can

767
00:43:19,480 --> 00:43:22,480
Speaker 1: still be harmful to the native Galapagos tortoises.

768
00:43:23,200 --> 00:43:25,239
Speaker 2: Right, And in fact, one example of this came up

769
00:43:25,320 --> 00:43:29,000
Speaker 2: in some episodes we did back in October on goats, right,

770
00:43:29,080 --> 00:43:32,480
Speaker 2: the issue of goats competing for resources with tortoises.

771
00:43:32,840 --> 00:43:37,000
Speaker 1: That's right again. Goats, as we discussed, are amazing at

772
00:43:37,040 --> 00:43:40,319
Speaker 1: what they do at roaming around finding odd bits of

773
00:43:40,600 --> 00:43:45,560
Speaker 1: vegetation to consume, and yeah, they're they're ultimately better at

774
00:43:45,600 --> 00:43:48,840
Speaker 1: it than tortoises. They're more thorough than the tortoises, and

775
00:43:49,719 --> 00:43:52,120
Speaker 1: ultimately so thorough that they can be even more disruptive

776
00:43:52,160 --> 00:43:55,360
Speaker 1: to like the to the ground itself, like you know,

777
00:43:56,000 --> 00:44:00,000
Speaker 1: getting in there and actually making it unstable. So that's

778
00:44:00,160 --> 00:44:03,080
Speaker 1: that's one thing to consider. Also when you're dealing with

779
00:44:03,120 --> 00:44:05,799
Speaker 1: any creature that lays its eggs in the ground. Not

780
00:44:05,880 --> 00:44:08,319
Speaker 1: only do you have to worry with certain species, like

781
00:44:08,400 --> 00:44:11,120
Speaker 1: especially pigs and rats going after those eggs and then

782
00:44:11,160 --> 00:44:14,680
Speaker 1: going after the young. Potentially, you also have to deal

783
00:44:14,760 --> 00:44:18,280
Speaker 1: with cattle because there are still cattle on the islands,

784
00:44:18,280 --> 00:44:21,520
Speaker 1: and cattle were brought to the islands, and cattle aren't

785
00:44:21,560 --> 00:44:24,839
Speaker 1: interested in really eating those tortoise eggs, but they will

786
00:44:24,840 --> 00:44:27,080
Speaker 1: definitely step on those tortoise eggs if they happen to

787
00:44:27,080 --> 00:44:28,360
Speaker 1: be ranging in the same area.

788
00:44:28,880 --> 00:44:32,960
Speaker 2: Now, in the previous episode, we talked about some hypotheses

789
00:44:33,000 --> 00:44:37,520
Speaker 2: about how marine iguanas first arrived on the Galapagos Islands,

790
00:44:38,040 --> 00:44:40,960
Speaker 2: probably via some kind of rafting from the mainland. Is

791
00:44:41,000 --> 00:44:44,160
Speaker 2: that also the idea of what likely happened with the

792
00:44:44,200 --> 00:44:45,440
Speaker 2: ancestral tortoises.

793
00:44:46,040 --> 00:44:49,279
Speaker 1: That's my understanding based on the sources I was looking at,

794
00:44:49,320 --> 00:44:54,400
Speaker 1: and based on conversations with some of the naturalist and

795
00:44:54,480 --> 00:44:57,640
Speaker 1: guides in the Galapagos Islands. The idea is that it

796
00:44:57,640 --> 00:45:01,120
Speaker 1: would have been much the same tortoises in South America,

797
00:45:01,360 --> 00:45:05,640
Speaker 1: swept up in river floods, washed out with vegetation which

798
00:45:05,680 --> 00:45:09,520
Speaker 1: they were able to raft on, and reaching these far

799
00:45:09,560 --> 00:45:10,360
Speaker 1: flung islands.

800
00:45:10,800 --> 00:45:15,319
Speaker 2: So it's amazing to imagine these extremely unlikely, kind of

801
00:45:15,360 --> 00:45:18,399
Speaker 2: one off events that allowed the population of each island,

802
00:45:18,440 --> 00:45:21,400
Speaker 2: because it's not something you see happening every day. But

803
00:45:21,719 --> 00:45:23,760
Speaker 2: you know, all it takes is a is a small

804
00:45:23,800 --> 00:45:27,040
Speaker 2: seed population to get there and then wow, what's this.

805
00:45:27,200 --> 00:45:30,200
Speaker 2: You know, there's all these food resources and no predators

806
00:45:30,200 --> 00:45:32,080
Speaker 2: and you can really boom once you arrive.

807
00:45:32,920 --> 00:45:35,000
Speaker 1: Yeah. And I'm not sure if the numbers on this

808
00:45:35,120 --> 00:45:40,560
Speaker 1: are you know, certified as it were, but it seems

809
00:45:40,760 --> 00:45:43,520
Speaker 1: like the first Glapacos tortoises probably reached the islands two

810
00:45:43,520 --> 00:45:47,000
Speaker 1: to three million years ago via rafting. They would have

811
00:45:47,000 --> 00:45:50,839
Speaker 1: probably arrived on the eastern islands of Espanola and San

812
00:45:50,960 --> 00:45:57,239
Speaker 1: Cristobile first and then spread west from there. So it's yeah,

813
00:45:57,400 --> 00:46:00,600
Speaker 1: it's interesting to think about. Now. The other question that

814
00:46:00,760 --> 00:46:03,560
Speaker 1: I guess came up for me, and this was like,

815
00:46:03,600 --> 00:46:06,760
Speaker 1: how big were these tortoises when they first arrived, because

816
00:46:07,280 --> 00:46:10,279
Speaker 1: at least some sources out there make the case that

817
00:46:10,280 --> 00:46:14,279
Speaker 1: they were already big, that they were already quote unquote gigantic,

818
00:46:15,160 --> 00:46:19,520
Speaker 1: while plenty of other sources also discuss Glapago's tortoises as

819
00:46:19,640 --> 00:46:21,319
Speaker 1: a case of island gigantism.

820
00:46:21,880 --> 00:46:26,239
Speaker 2: Yeah, so island gigantism is something that often occurs. There's

821
00:46:26,880 --> 00:46:29,799
Speaker 2: known as island dwarfism and island gigantism. These kind of

822
00:46:30,480 --> 00:46:35,040
Speaker 2: runaway pressures on the size of animals that can really

823
00:46:35,760 --> 00:46:39,040
Speaker 2: bulk them up or shrink them down when they're in

824
00:46:39,080 --> 00:46:42,480
Speaker 2: a contained ecosystem like an island. And I don't think

825
00:46:42,520 --> 00:46:44,520
Speaker 2: we know exactly what all the pressures would be, but

826
00:46:44,560 --> 00:46:47,600
Speaker 2: you could imagine something like, well, maybe there is always

827
00:46:47,640 --> 00:46:51,680
Speaker 2: sexual selection on, say the size of adult male tortoises,

828
00:46:51,719 --> 00:46:53,960
Speaker 2: to make them bigger and bigger, because the bigger you are,

829
00:46:54,040 --> 00:46:56,760
Speaker 2: the more likely a female is to be receptive to mating.

830
00:46:57,200 --> 00:46:59,880
Speaker 2: So there's a sexual selection driving them to be bigger.

831
00:47:00,239 --> 00:47:03,560
Speaker 2: But then there's naturally some kind of other pressure that

832
00:47:03,640 --> 00:47:06,560
Speaker 2: wants to keep their size smaller. You know, like you

833
00:47:07,040 --> 00:47:10,040
Speaker 2: there's that advantage in being bigger. But once you're bigger,

834
00:47:10,080 --> 00:47:12,760
Speaker 2: maybe you're more at risk of predation, or it's harder

835
00:47:12,760 --> 00:47:16,120
Speaker 2: to thermoregulate or something like that. And you can imagine

836
00:47:16,160 --> 00:47:18,719
Speaker 2: cases where you get on an island and suddenly those

837
00:47:18,760 --> 00:47:21,799
Speaker 2: other pressures are relieved and so you can just keep

838
00:47:21,840 --> 00:47:23,920
Speaker 2: getting bigger and bigger than you would have been allowed

839
00:47:23,920 --> 00:47:24,880
Speaker 2: to on the mainland.

840
00:47:25,600 --> 00:47:25,839
Speaker 3: Yeah.

841
00:47:25,920 --> 00:47:30,240
Speaker 1: Yeah, I guess on the like supporting the idea that

842
00:47:30,320 --> 00:47:33,880
Speaker 1: they were already big there is. There is, of course,

843
00:47:33,920 --> 00:47:37,799
Speaker 1: fossil evidence of gigantic tortoises existing on I think every

844
00:47:37,840 --> 00:47:43,080
Speaker 1: continent except Australia and Antarctica at some point in the past,

845
00:47:43,760 --> 00:47:47,840
Speaker 1: so it's not like these forms only emerged on various

846
00:47:47,840 --> 00:47:50,880
Speaker 1: islands island environments. But I don't know. On the other hand,

847
00:47:50,920 --> 00:47:53,920
Speaker 1: it seems like plenty of sources are discussing this as gigantism.

848
00:47:54,400 --> 00:47:57,320
Speaker 1: One paper I was looking at this is from Jaffe

849
00:47:57,360 --> 00:47:59,960
Speaker 1: at All, from a twenty eleven paper in the Royal

850
00:48:00,120 --> 00:48:03,440
Speaker 1: Society Biology Letters, The Evolution of Island gigantism and body

851
00:48:03,480 --> 00:48:08,000
Speaker 1: size variation in Tortoises and turtles. They point out that

852
00:48:08,400 --> 00:48:11,080
Speaker 1: they do point out that quote, the other evolutionary determinants

853
00:48:11,120 --> 00:48:15,440
Speaker 1: of size diversity in Chilonians are poorly understood. But they

854
00:48:15,480 --> 00:48:18,440
Speaker 1: also point out that Chelonians span some four orders of

855
00:48:18,480 --> 00:48:21,960
Speaker 1: magnitude in their sizes, and that there is quote a

856
00:48:22,000 --> 00:48:27,520
Speaker 1: pronounced relationship between habitat and optimal body size. Also worth

857
00:48:27,600 --> 00:48:30,640
Speaker 1: noting that the apparently the closest living relative to the

858
00:48:30,640 --> 00:48:36,120
Speaker 1: Galapagos tortoise is not a direct ancestor of those tortoises,

859
00:48:36,520 --> 00:48:40,799
Speaker 1: but it is itself a relatively small bodied variety of

860
00:48:40,840 --> 00:48:45,000
Speaker 1: tortoise that's found in South America, the Chaco tortoise, I

861
00:48:45,000 --> 00:48:47,480
Speaker 1: believe it is called now. I also mentioned that there

862
00:48:47,520 --> 00:48:50,040
Speaker 1: are other giant tortoises still in the world outside of

863
00:48:50,040 --> 00:48:54,560
Speaker 1: the Galapagos. These would be giant tortoises that survived in

864
00:48:54,680 --> 00:48:58,440
Speaker 1: the Western Indian Ocean in the form of Aldabra giant

865
00:48:58,440 --> 00:49:00,279
Speaker 1: tortoises leave.

866
00:49:00,280 --> 00:49:04,440
Speaker 2: When Darwin arrived, he thought that these were the same species,

867
00:49:04,520 --> 00:49:06,319
Speaker 2: like that the ones on the Galapagos were the same

868
00:49:06,400 --> 00:49:09,600
Speaker 2: as those, or at least the same as some other

869
00:49:09,800 --> 00:49:12,040
Speaker 2: island gigantic tortoise he was aware of. I think it

870
00:49:12,040 --> 00:49:13,759
Speaker 2: would have been those, because those are the only other

871
00:49:13,760 --> 00:49:17,480
Speaker 2: ones I know of, and he was mistaken in that

872
00:49:17,760 --> 00:49:21,560
Speaker 2: in fact that they're just they're different parallel forms of

873
00:49:21,920 --> 00:49:25,759
Speaker 2: gigantic tortoises. But one last thing I wanted to talk

874
00:49:25,760 --> 00:49:28,920
Speaker 2: about with these tortoises before we wrap up today is

875
00:49:29,040 --> 00:49:33,240
Speaker 2: the differences in the shell shapes, because we mentioned earlier

876
00:49:33,239 --> 00:49:37,520
Speaker 2: that some species have more dome shaped shells and some

877
00:49:37,640 --> 00:49:42,120
Speaker 2: have these saddle shaped shells, and there are also intermediate

878
00:49:42,160 --> 00:49:46,240
Speaker 2: species that have sort of somewhere in between. A creature

879
00:49:46,280 --> 00:49:48,600
Speaker 2: and Laughlin have a great section on this in their

880
00:49:48,680 --> 00:49:51,359
Speaker 2: chapter on the tortoises, and I wanted to talk about

881
00:49:51,360 --> 00:49:53,880
Speaker 2: it a bit. So one of the questions is why

882
00:49:55,320 --> 00:49:59,239
Speaker 2: you can observe some things that might lead to these differences.

883
00:50:00,080 --> 00:50:03,319
Speaker 2: The tortoises with the domed shells tend to live more

884
00:50:03,320 --> 00:50:06,680
Speaker 2: in the highlands and around caldera rims, where vegetation is

885
00:50:06,760 --> 00:50:11,880
Speaker 2: much thicker and lush all the time, whereas the ones

886
00:50:11,880 --> 00:50:14,799
Speaker 2: with the saddle backed shells tend to live more or

887
00:50:14,800 --> 00:50:18,120
Speaker 2: even exclusively in the low lands, where conditions are more

888
00:50:18,160 --> 00:50:22,160
Speaker 2: often dry. Of course, the differences in these shells is

889
00:50:22,200 --> 00:50:24,480
Speaker 2: that while as the domed ones are more just kind

890
00:50:24,480 --> 00:50:28,680
Speaker 2: of like an upturned cup over the reptiles back. The

891
00:50:28,760 --> 00:50:33,080
Speaker 2: saddleback tortoises, their shell tends to have like a relief

892
00:50:33,280 --> 00:50:35,800
Speaker 2: area above the head and neck. It's almost like a

893
00:50:36,320 --> 00:50:40,359
Speaker 2: collar that's pulled back. And there are some other differences too.

894
00:50:40,440 --> 00:50:43,480
Speaker 2: The domed tortoises tend to have a larger body size,

895
00:50:43,520 --> 00:50:47,759
Speaker 2: but shorter legs and necks, whereas the saddleback tortoises tend

896
00:50:47,800 --> 00:50:52,200
Speaker 2: to be smaller overall but have longer legs and longer necks.

897
00:50:52,840 --> 00:50:53,560
Speaker 4: Now, remember in the.

898
00:50:53,560 --> 00:50:56,600
Speaker 2: Last episode when we talked about the marine iguanas and

899
00:50:56,640 --> 00:51:01,480
Speaker 2: we were trying to come up with the biological explanation

900
00:51:01,600 --> 00:51:05,080
Speaker 2: for why the iguana kept returning out of the water

901
00:51:05,160 --> 00:51:07,759
Speaker 2: after Darwin threw it in, even though you know it's

902
00:51:07,800 --> 00:51:10,279
Speaker 2: got to go in the water all the time to eat,

903
00:51:10,400 --> 00:51:12,200
Speaker 2: So why doesn't it just stay in the water to

904
00:51:12,320 --> 00:51:15,640
Speaker 2: stay away from him? And the answer we came up

905
00:51:15,680 --> 00:51:18,759
Speaker 2: with that the Darwin did not land on himself is

906
00:51:18,760 --> 00:51:23,480
Speaker 2: that it's probably for thermoregulation reasons because the water is

907
00:51:23,560 --> 00:51:26,680
Speaker 2: cold and it was removing heat from the iguana's body

908
00:51:26,920 --> 00:51:29,040
Speaker 2: and the iguana needs to get back up on land

909
00:51:29,160 --> 00:51:33,560
Speaker 2: to heat back up. I think a good explanation for

910
00:51:33,960 --> 00:51:37,400
Speaker 2: One of the explanations for the different body plans of

911
00:51:37,440 --> 00:51:41,400
Speaker 2: these different tortoises probably also has to do with reptile

912
00:51:41,560 --> 00:51:47,240
Speaker 2: thermoregulation with the regulation of body temperature, because of course,

913
00:51:47,520 --> 00:51:52,480
Speaker 2: animals with a larger body volume also tend to retain

914
00:51:52,680 --> 00:51:57,400
Speaker 2: more heat because they have less surface area proportional to

915
00:51:57,440 --> 00:52:00,000
Speaker 2: their volume. So if you're living in a cold place

916
00:52:00,480 --> 00:52:03,440
Speaker 2: and you're trying to retain body heat, it's easier to

917
00:52:03,480 --> 00:52:05,839
Speaker 2: do that if you're bigger. You've got there's just more

918
00:52:06,040 --> 00:52:10,000
Speaker 2: body in there and less relatively less surface area, and

919
00:52:10,120 --> 00:52:13,480
Speaker 2: vice versa. It's easier to cool off if you're smaller,

920
00:52:13,520 --> 00:52:16,880
Speaker 2: because a bigger percent of your body is surface area

921
00:52:16,960 --> 00:52:19,840
Speaker 2: that you can lose heat through. This would seem to

922
00:52:19,920 --> 00:52:24,319
Speaker 2: correlate with the observation that the domed tortoises, which live

923
00:52:24,400 --> 00:52:26,200
Speaker 2: up in the highlands where it tends to be a

924
00:52:26,200 --> 00:52:29,280
Speaker 2: little bit cooler, tend to have a larger body size

925
00:52:29,280 --> 00:52:33,760
Speaker 2: but also shorter legs and necks, so less extremities poking

926
00:52:33,800 --> 00:52:37,680
Speaker 2: out that can lose heat, whereas the saddleback tortoises tend

927
00:52:37,680 --> 00:52:41,360
Speaker 2: to be smaller overall, with longer legs and longer necks

928
00:52:41,400 --> 00:52:44,399
Speaker 2: and they live down in the lowlands where things tend

929
00:52:44,400 --> 00:52:44,960
Speaker 2: to be hotter.

930
00:52:45,680 --> 00:52:45,919
Speaker 4: Yeah.

931
00:52:46,040 --> 00:52:48,200
Speaker 1: Yeah, Now, most of the tortoises I got to observe

932
00:52:48,239 --> 00:52:55,240
Speaker 1: were definitely in highland environments, but their relationship with temperature

933
00:52:55,320 --> 00:52:58,880
Speaker 1: is notable as well. In one case, we've got to

934
00:52:58,880 --> 00:53:02,960
Speaker 1: go out and see these tortoises out there in this

935
00:53:02,960 --> 00:53:06,520
Speaker 1: this this this highland area, and it was early enough

936
00:53:06,520 --> 00:53:08,680
Speaker 1: in the day that some of them were essentially sleeping in.

937
00:53:08,760 --> 00:53:11,799
Speaker 1: They were still bedded down in the mud where they

938
00:53:11,880 --> 00:53:14,720
Speaker 1: could they could, you know, keep their temperature relatively stable

939
00:53:14,760 --> 00:53:17,239
Speaker 1: throughout the night. And some were already getting up to

940
00:53:17,239 --> 00:53:21,000
Speaker 1: begin their their day of eating. Others just weren't quite

941
00:53:21,000 --> 00:53:21,640
Speaker 1: ready yet.

942
00:53:22,040 --> 00:53:24,480
Speaker 2: Oh yeah, And I've read that these tortoises just love

943
00:53:24,560 --> 00:53:26,879
Speaker 2: the mud, like they'll love to get in the mud

944
00:53:26,920 --> 00:53:29,520
Speaker 2: puddles and they'll just hang out there for days sometimes.

945
00:53:30,080 --> 00:53:32,120
Speaker 1: Yeah, so you'll see them trooping around and yeah, on

946
00:53:32,120 --> 00:53:34,279
Speaker 1: one level, they kind of look like bulldozers because they're

947
00:53:34,280 --> 00:53:37,040
Speaker 1: just covered with mud, and of course they've been eating too.

948
00:53:37,280 --> 00:53:39,200
Speaker 1: There are lots of pictures you included one here of

949
00:53:39,280 --> 00:53:43,000
Speaker 1: one with just this spectacularly messy's face from all the

950
00:53:43,640 --> 00:53:47,000
Speaker 1: vegetation and or fruits it's been consumed. It's just smeared

951
00:53:47,000 --> 00:53:47,439
Speaker 1: all over.

952
00:53:48,040 --> 00:53:50,239
Speaker 2: It's like one of those gross baby pictures where the

953
00:53:50,239 --> 00:53:52,879
Speaker 2: baby just looks they've been face down in a play

954
00:53:52,920 --> 00:53:53,520
Speaker 2: of spaghetti.

955
00:53:54,000 --> 00:53:57,640
Speaker 1: Yeah, and their face, the face of the Glabgos tortoise

956
00:53:57,680 --> 00:54:01,600
Speaker 1: does kind of look like like old baby, so it

957
00:54:01,680 --> 00:54:03,520
Speaker 1: really matches up with that well.

958
00:54:03,560 --> 00:54:07,399
Speaker 2: But there are other differences in the environments that might

959
00:54:07,440 --> 00:54:11,440
Speaker 2: explain the different body plans of these tortoise species, So

960
00:54:12,160 --> 00:54:14,200
Speaker 2: a lot of it probably has to do with vegetation.

961
00:54:14,480 --> 00:54:14,640
Speaker 4: Right.

962
00:54:15,080 --> 00:54:18,440
Speaker 2: Domed tortoises tend to live in more lush highlands with

963
00:54:18,640 --> 00:54:23,440
Speaker 2: dense undergrowth and a creature in Laughlin right quote. The

964
00:54:23,480 --> 00:54:27,400
Speaker 2: domed shells, smoothly rounded as they are, may prove adaptive.

965
00:54:27,480 --> 00:54:31,680
Speaker 2: Is the tortoises move tank like through dense plant cover,

966
00:54:31,800 --> 00:54:35,040
Speaker 2: which is of course also the animal's food source. On

967
00:54:35,120 --> 00:54:38,440
Speaker 2: the other hand, saddle type shells with a large forward

968
00:54:38,600 --> 00:54:43,120
Speaker 2: notch can actually become snagged in low vegetation, impeding the

969
00:54:43,120 --> 00:54:46,640
Speaker 2: movement of the tortoise. Saddle shells are not very adaptive

970
00:54:46,719 --> 00:54:49,560
Speaker 2: in low dense vegetation, so it's just going to be

971
00:54:49,600 --> 00:54:53,719
Speaker 2: easier to move around with a more rounded shell. In

972
00:54:53,800 --> 00:54:57,320
Speaker 2: all that thick brush in the Upper Highland forest regions,

973
00:54:57,680 --> 00:55:00,400
Speaker 2: whereas if you had the saddle shell with the turned

974
00:55:00,480 --> 00:55:02,200
Speaker 2: sort of collar in the front, Yeah, they'd just be

975
00:55:02,239 --> 00:55:03,840
Speaker 2: getting hooked on stuff all the time.

976
00:55:04,280 --> 00:55:06,680
Speaker 1: And I mean they are little bulldozers. They can tear

977
00:55:06,840 --> 00:55:10,040
Speaker 1: stuff up. Like for instance, you know there are gonna

978
00:55:10,040 --> 00:55:13,480
Speaker 1: be limits. They could continue, you know, be slowed down

979
00:55:13,560 --> 00:55:16,799
Speaker 1: or I guess stuck in vegetation. But to give one

980
00:55:16,800 --> 00:55:19,399
Speaker 1: example that I was told about, do you have again

981
00:55:19,480 --> 00:55:23,120
Speaker 1: individuals who are still ranching in these in these parts

982
00:55:23,160 --> 00:55:25,960
Speaker 1: of the Highland, they have cows. They need to contain

983
00:55:26,000 --> 00:55:30,040
Speaker 1: those cows. But if they're gonna be tortoises moving through,

984
00:55:30,480 --> 00:55:33,399
Speaker 1: they're gonna they're just gonna take down your barbed wire

985
00:55:33,480 --> 00:55:35,759
Speaker 1: fence or your your whatever kind of fencing you have.

986
00:55:36,200 --> 00:55:39,080
Speaker 1: So in many cases they'll have the fencing, they'll have

987
00:55:39,120 --> 00:55:41,440
Speaker 1: this big gap at the bottom that will allow a

988
00:55:41,480 --> 00:55:43,399
Speaker 1: tortoise to move through, because that way you still get

989
00:55:43,400 --> 00:55:45,879
Speaker 1: to have your fence and the tortoise won't won't tear

990
00:55:45,920 --> 00:55:48,400
Speaker 1: it down when it makes a bee line for whatever

991
00:55:48,440 --> 00:55:49,120
Speaker 1: wherever it's going.

992
00:55:49,440 --> 00:55:52,960
Speaker 2: Yeah, fortunately the cows can't crawl under Yeah.

993
00:55:52,800 --> 00:55:56,160
Speaker 1: I guess not. It did raise some questions like, well, yeah,

994
00:55:56,160 --> 00:55:59,160
Speaker 1: can the cow what about really short cows? I don't know,

995
00:55:59,440 --> 00:56:00,560
Speaker 1: but apparently it works.

996
00:56:01,200 --> 00:56:04,040
Speaker 2: But the final thing with the difference between the domed

997
00:56:04,120 --> 00:56:07,440
Speaker 2: tortoises and the saddlebacks is probably food sources as well,

998
00:56:07,480 --> 00:56:11,600
Speaker 2: because again, the domed ones are going to be munching

999
00:56:11,640 --> 00:56:14,600
Speaker 2: on a lot of you know, lush, low lying vegetation,

1000
00:56:15,800 --> 00:56:18,719
Speaker 2: so you know, that's just that's okay to have a

1001
00:56:18,760 --> 00:56:22,600
Speaker 2: normal kind of dome dome shaped shell for that. But

1002
00:56:23,320 --> 00:56:26,600
Speaker 2: the saddleback tortoises, which live in the more arid lowlands,

1003
00:56:27,160 --> 00:56:31,719
Speaker 2: are going to be eating cacti, often tall cacti that

1004
00:56:31,920 --> 00:56:34,839
Speaker 2: they need to reach up to get to, and so

1005
00:56:35,080 --> 00:56:38,040
Speaker 2: the upturned front of the shell allows more room to

1006
00:56:38,239 --> 00:56:40,319
Speaker 2: raise the neck, and of course, of course, as I

1007
00:56:40,320 --> 00:56:42,960
Speaker 2: said as well, they've got longer necks and longer legs

1008
00:56:42,960 --> 00:56:46,400
Speaker 2: to help reach Robin, I think you said you observe

1009
00:56:46,480 --> 00:56:50,040
Speaker 2: stuff about those cactuses sort of reacting to that by

1010
00:56:50,160 --> 00:56:54,000
Speaker 2: growing taller and taller to try to escape the munching tortoises.

1011
00:56:54,600 --> 00:56:57,799
Speaker 1: Yeah. Yeah, And it's it's remarkable to see because yeah,

1012
00:56:57,840 --> 00:57:02,320
Speaker 1: here's this, here's this cac that has evolved to thrive

1013
00:57:02,520 --> 00:57:04,680
Speaker 1: alongside the tortoises, and it ends up, Yeah, it ends

1014
00:57:04,760 --> 00:57:06,880
Speaker 1: up feeling more like a tree than a cactus, if

1015
00:57:06,920 --> 00:57:13,480
Speaker 1: that makes sense. Yeah, it's a remarkable ecosystem.

1016
00:57:12,080 --> 00:57:12,480
Speaker 4: All right.

1017
00:57:12,520 --> 00:57:14,520
Speaker 1: So there you have it. Hopefully we gave just at

1018
00:57:14,600 --> 00:57:20,920
Speaker 1: least a nice snapshot, a nice overview of the Galapagos tortoise. Obviously,

1019
00:57:20,960 --> 00:57:23,720
Speaker 1: there's a lot of research out there about these creatures,

1020
00:57:23,760 --> 00:57:28,120
Speaker 1: so perhaps there's some details that we managed to leave out.

1021
00:57:28,200 --> 00:57:30,040
Speaker 1: If you think that we left out something that is

1022
00:57:30,040 --> 00:57:33,280
Speaker 1: particularly exciting, then right in. We'd love to hear about it.

1023
00:57:33,320 --> 00:57:35,240
Speaker 1: We'd love to see it for ourselves and to share

1024
00:57:35,280 --> 00:57:37,880
Speaker 1: it in a future listener mail. Likewise, as I mentioned

1025
00:57:37,880 --> 00:57:40,400
Speaker 1: the first one, if you've traveled with the Glabgos Islands,

1026
00:57:40,440 --> 00:57:45,960
Speaker 1: if you live on the Galapagos Islands or are an Ecuadorian,

1027
00:57:46,440 --> 00:57:48,040
Speaker 1: we would also love to hear from you. We love

1028
00:57:48,080 --> 00:57:51,840
Speaker 1: your thoughts on these fabulous creatures that we've discussed here,

1029
00:57:51,960 --> 00:57:54,080
Speaker 1: or any of the other creatures of the Glabgos Islence,

1030
00:57:54,760 --> 00:57:57,920
Speaker 1: I'm always excited to hear more. Just a reminder to

1031
00:57:57,960 --> 00:58:00,840
Speaker 1: everybody's Stuff to blow your mind. Publishes us it's core

1032
00:58:00,880 --> 00:58:03,240
Speaker 1: episodes on Tuesdays and Thursdays. In the Stuff to Blow

1033
00:58:03,240 --> 00:58:07,040
Speaker 1: Your Mind podcast feed we have listener mail episodes on Mondays,

1034
00:58:07,200 --> 00:58:10,800
Speaker 1: a short form artifact or monster fact episode on Wednesdays,

1035
00:58:10,840 --> 00:58:13,440
Speaker 1: and on Fridays we set aside most serious concerns and

1036
00:58:13,680 --> 00:58:15,400
Speaker 1: just talk about a weird film.

1037
00:58:15,760 --> 00:58:19,520
Speaker 2: Huge thanks to our audio producer, Max Williams. If you

1038
00:58:19,560 --> 00:58:23,080
Speaker 2: would like to get in touch with this with this podcast,

1039
00:58:23,160 --> 00:58:26,920
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1040
00:58:26,920 --> 00:58:30,160
Speaker 2: any other, with a suggestion for a future episode topic,

1041
00:58:30,320 --> 00:58:32,480
Speaker 2: or just to say hello, you can email us at

1042
00:58:32,640 --> 00:58:41,800
Speaker 2: contact at stuff to Blow your Mind dot com.

1043
00:58:43,520 --> 00:58:46,400
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1044
00:58:46,520 --> 00:58:49,280
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00:58:49,440 --> 00:58:58,120
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1046
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