November 23, 2023 • 59 mins
In this classic episode of Stuff to Blow Your Mind, Robert and Joe discuss some of the most famous reptilian residents of the Galapagos archipelago, including the world’s largest extant tortoise species and the world’s only marine iguana. (originally published 12/10/2022)
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:06):
Hey you welcome to Stuff to Blow Your Mind. My
name is Robert.
Speaker 2 (00:09):
Lamb and I am Joe McCormick, and today we're bringing
you an episode from the vault. This is part two
of our series on the reptiles of the Galapagos. This
was originally published December tenth, twenty twenty two.
Speaker 3 (00:20):
Enjoy Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Speaker 1 (00:34):
Hey, welcome to Stuff to Blow your Mind. My name
is Robert.
Speaker 2 (00:37):
Lamb and I'm Joe McCormick, and we're back with part
two of our series on the reptiles of the Galapagos Islands. Now,
in the previous episode, we focused mainly on the marine iguana,
or as they were often referred to early on, those
hideous creatures, those stupid, awful, sluggish lizards. We mounted a
(00:58):
defense of the marine iguana. But today we are here
to talk about the Galapagos tortoise. And I wanted to
kick things off by reading a passage from Charles Darwin
in the Voyage of the Beagle. Darwin, of course, was
not just a great scientist, but a really wonderful writer,
and I think this will help set the scene. So
(01:19):
are you ready to hear about Darwin's first vision of
San Cristobal Island. Then then what they called Chatham Island.
Speaker 1 (01:27):
Yeah, let's let's hear from from old Charles.
Speaker 2 (01:29):
And this is part of a narrative of when he
slept ashore one night on the island. So off the boat,
Darwin writes. The entire surface of this part of the
island seems to have been permeated like a sieve by
the subterranean vapors. Here and there the lava, whilstsoft, has
been blown into great bubbles, and in other parts the
(01:52):
tops of caverns similarly formed have fallen in, leaving circular
pits with steep sides. From the regular form of the
many craters. They gave to the country an artificial appearance
which vividly reminded me of those parts of Staffordshire, where
the great iron foundries are most numerous. The day was
(02:12):
growing hot, and the scrambling over the rough surface and
through the intricate thickets was very fatiguing, but I was
well repaid by the strange Cyclopean scene. As I was
walking along, I met two large tortoises, each of which
must have weighed at least two hundred pounds. One was
eating a piece of cactus, and as I approached, it
(02:35):
stared at me and slowly walked away.
Speaker 4 (02:37):
The other gave a.
Speaker 2 (02:39):
Deep hiss and drew in its head. These huge reptiles,
surrounded by the black lava, the leafless shrubs and large
cacti seemed to my fancy like some Antediluvian animals. The
few dull colored birds cared no more for me than
they did for the great tortoises. So Darwin transported to
(03:01):
a time from before Noah's flood by the vision of
these bizarre, gigantic tortoises crawling around on the on the lava.
Speaker 1 (03:11):
Yes, this is the great sceni paints here and and yeah.
As I mentioned in the first episode, I was. I
was fortunate enough to get to travel to the Galapagos
Islands just a couple of months ago. In San Cristobo
Island was one of the islands that I got to visit,
and this was pretty much the the experience I had
with my family walking through one of the the areas
(03:33):
they had set aside for these magnificent tortoises. They're just
they just they walk around as if yeah, if you
don't matter, unless you get a little too close for
their liking, in which case there'll often be this hiss
and this retraction of their head. I mean, their heads
don't retract in the same way that say, a box
turtle does, but they're able to sort of pull their
(03:54):
head in a bit. But that the hissing that Darwin
is describing here, it does have a very, I don't know,
pneumatic kind of quality to it. It feels it sounds
like some sort of machinery. And indeed, that's that's kind
of more what it is, as opposed to like the
hiss you might hear from a house cat or something.
And one of the things that I kept thinking about
(04:16):
while encountering them is that they already move with this
kind of herky jerky kind of locomotion. They already move
like they are elaborate mechanical creatures created for practical effects
for a nineteen nineties science fiction feature. And then they
(04:36):
also make this hissing sound to move part of their anatomy.
So it almost creates this feeling of am I seeing
real animals or is this an elaborate hoax these animatronics? Yeah, yeah, yeah,
they feel almost like animatronics, but of course they're they're
they're they're quite alive, and they're quite, but that's part
of their strangeness, and they just the awe of watching
(04:57):
these giant creatures walk arou around, slowly, eat, and occasionally
have some startling interactions.
Speaker 2 (05:04):
Now I'm greatly envious of the opportunity you got to
see these animals in person, but I trust that you
did not do what Darwin did upon encountering these beasts
and try to ride them.
Speaker 1 (05:17):
Absolutely not, no, no. The only time the times we
were forced to get uncomfortably close in one of these
situations of the area that we were walking through had
a path and you're supposed to stay on the path
and keep your distance from the tortoises. Sometimes though the
tortoises will just get on the path. You have to
find your way around them, and they don't necessarily like that.
(05:40):
But we kept our distance, and you want to keep
your distance because, yeah, if you get a little too close,
they're going to stop interacting with their environment for a
little bit. And if you don't want to watch that,
you want to watch them eat and rampage around and
occasionally have these fabulous stare downs between two males which
(06:01):
I don't know, we may describe this later, So maybe
I shouldn't get into that just yet.
Speaker 2 (06:04):
Yeah, yeah, we can talk about the mock fights later on.
So the Galapagos tortoise is I think you would say,
originally the dominant land herbivore of the Galapagos Islands, which
makes them kind of unique because there's pretty much nowhere
else on Earth now where the dominant land herbivore is
(06:25):
a reptile. So these are very unique and beautiful creatures,
and the Glapagos tortoise stands out so much among the
endemic fauna that it's actually the origin of the archipelago's
name in one way or another. There's a little bit
of nitpicking on that, but basically it goes like this.
By the fifteen seventies, these islands had already appeared on
(06:48):
at least a couple of European maps. The one I
saw named was by a Flemish cartographer named Abraham Ortelius,
and it named the islands Insulae de los galapago or
meaning Islands of the Tortoises. Now, the nitpicking about the
terminology I've read is what exactly the word galapago or
(07:09):
Galapagos originally meant. According to a book that I'm going
to reference multiple times in this episode, Galapagos and Natural History,
second Edition by John Creecher and Kevin Laughlin from Princeton
University Press. That editions out just twenty twenty two. They
write that the origin of the name of the islands
is an old Spanish word, galapago, which was a name
(07:33):
for a specific type of saddle. So there's like, you know,
a saddle you'd use on a horse. I guess that
has a kind of upturned front. That was a galapago.
And some, but not all, of the Galapagos tortoises have
saddle shaped shells. Others have a more straightforward dome. And
we can talk about the evolutionary reasons for those differences
(07:53):
later on. But when Tamas de Berlanga landed on the
islands in fifteen thirty five, a story we talked about
in the previous episode. After this, he wrote a letter
to the king in which he observed describing the animals
of the island, he observed mucos lobos marinos meaning many
sea lions, tortugas meaning sea turtles, iguanas, and Galapagos, and
(08:17):
the authors write that this is probably a reference to
the tortoises and their saddle shaped shells rather than to
literal saddles being on the island.
Speaker 1 (08:26):
This is a solid observation that thankfully still holds true today.
Mucos lobos marinos and tortugas, iguanas and tortoises. Yes, yeah,
the sea lion, I mean the mucco lobos marinos. That
was probably the most astounding of all when you're near
the coast, because they're everywhere and sometimes laying. There'll be
(08:47):
like a male that's come up and he's like laying
in the street, or they they love park benches. There
are a lot of fun to wide.
Speaker 4 (08:54):
Well.
Speaker 2 (08:55):
The difference in the Spanish name. I guess if it's
lobo marino that would mean see wolf, not sea lion, right,
But that that heightens the kind of implicit comedy of
naming these animals after what you would think of as
a more actively voracious land predator, whereas you know, I
guess when they're on the land, they're not quite so
threatening as maybe a wolf for a lion would seem.
Speaker 1 (09:16):
Yeah, I mean, well, on one hand, yeah, you have
some of the little tiny islands are at least one
that's named for the wolves for the lobos, and of
course that's why, because sea lions are hanging out there
and yeah, on the on the on the beach. They're
often quite docile and you see people getting way too
close to them in some cases. But the big males,
of course, are very territorial about hanging on to their
(09:38):
bit of property and their and their females, you know,
their their their beach real estate, and so there of
course always they're continuously loudly sending the alarm and occasionally
chasing off other males. So there's there's a lot of
drama if you just sit back and watch the sea lions.
And I imagine that listeners from other parts of the
(09:59):
world can to this as well.
Speaker 2 (10:01):
Yes, yes, keep your distance, folks, I mean, observe, but
there's no reason to get in the sea lion space.
Speaker 1 (10:08):
Though sometimes in my experience, sea lion will come for
your space. I was just seated away from sea lions
and then here comes this female and she's just howling
about something and insists on taking my spot on a log,
and I'm like, it's yours at yours, and then she
just hangs out on the log for a few minutes
and then leaves it. I don't know, She's just trying
to make a point.
Speaker 2 (10:30):
So if you have never seen the Galopagos tortoises before,
you can easily find lots of pictures of them. But
to briefly describe the adults, there are many different species
scattered across the different islands. Maybe we can get into
the exact numbers on that in a bit, but generally
what they all have in common is that they're very large.
They have large shells, some species with rounded dome tops,
(10:53):
others with the saddle shape that Burlonga probably observed, which
are typically turned up in the front to have a
kind of big notch above the animal's head and neck.
They have long, dry, wrinkly necks which are surprisingly slim,
almost I dare say snake like in a way. They
(11:13):
have blunt, round snouts and a beak like mouth with
no teeth, and everywhere you can see their their skin.
In between the shell parts there is typically a lot
of leathery, wrinkly flesh, which just makes them look like
old people.
Speaker 1 (11:30):
Yeah, they they have this kind of appearance of a
of acute shriveled old person.
Speaker 4 (11:35):
Vase.
Speaker 1 (11:36):
Uh. They're they're very They're very sweet to look at
it's it's it's kind of hard to to not anthropomorphize
them as such even and and that can, of course,
can become complicated when you start considering like the full
range of their of their lifestyle and the way that
they they live and reproduce and so forth. Uh, it
never pays to anthropomorphize creatures too much.
Speaker 4 (11:59):
Yeah.
Speaker 2 (11:59):
Now, no one thing many of us today might not appreciate,
even if you go to the Galapagos today or if
you see Good Nature documentary footage from there, is how
many tortoises there were when people first arrive, Before the
animals had any natural predators other than the threat post
to hatchlings by the Galapagos Hulk, this place was swarming
(12:22):
with tortoises. And to try to get a picture of that,
I wanted to cite some basically math work that Creature
and Laughlin do in their book. So they're talking about
the reproductive rates of these tortoises. So they say, if
a female tortoise has more than two young that survive
(12:43):
into adulthood, the tortoise population will grow, so she has
replaced both her and her mate. And if she has
more than one, the population will grow and they say, Now,
consider that a female tortoise may conservatively lay five to
ten eggs annually for perhaps eighty years or more. So,
(13:04):
just for a very conservative estimate, they say, Okay, imagine
she averages one annual clutch and there's just three eggs
in it. That's kind of a small estimate. But there's
just three eggs per clutch. That's more than two hundred
eggs in a single adult female tortoises lifetime. They say, realistically,
the number is probably a multiple of that. So they're
(13:24):
going to have a lot of young and there before
humans arrive and bring their invasive species with them, before
they bring dogs and pigs and stuff. There is not
significant predation at any life cycle. A part of the
life cycle of a tortoise. There's some minor predation by
like hawks of the babies, but most of them are
(13:45):
going to grow and become reproducing adults.
Speaker 1 (13:49):
Yeah, it's pretty amazing. Amazing. I ask one of the
guides about, you know, how long are the females reproductive?
Because you see some very who was pointed that My
guide here was pointing out the various the old tortoises.
But because you can sort of tell by looking at
their shells the way that the line, like, for a while,
you can sort of it's not like you can count
the rings exactly, but you can sort of see the
(14:11):
rings and the patterns on their shell. But eventually there's
kind of like a smoothing out that occurs, and those
are the really old ones. And the guy was like, yeah,
we're not entirely sure, but it seems like they're reproductively
active for pretty much most of their lives, which is
the astounding.
Speaker 2 (14:38):
Yeah, it's amazing. And so the authors of this book
end up concluding that before humans arrived and brought these
invasive predators with them and started harvesting the tortoises themselves,
which is a sad fact we'll talk about in a moment,
the tortoises.
Speaker 4 (14:54):
Were just.
Speaker 2 (14:56):
Profuse.
Speaker 4 (14:57):
They were everywhere.
Speaker 2 (14:58):
They say, there's a conserva estimate of a total population
of two hundred and fifty thousand tortoises just on this
small group of islands. But of course, today all of
these tortoise populations are at least vulnerable, and some are
up to critically endangered, and that's after a significant bounce
back in some cases, you know, after conservation efforts kicked in.
(15:22):
So what happened to these tortoises. Well, one thing that
happened is is something Darwin talks about in his Passage
and Voyage of the Beagle. Before he even really gets
to ecological observations about the tortoises, he writes at length
about people eating them. So, in describing the small human
(15:43):
colony on what was then Charles Island what today is
called Floriana Island, so Darwin writes, in the woods there
are many wild pigs and goats. Now remember those are
not native to the islands, but introduced by humans. Darwin
goes on, But the staple article of animal food is
supplied by the tortoises. Their numbers have of course been
(16:04):
greatly reduced in this island, but the people yet count
on two days hunting, giving them food for.
Speaker 4 (16:09):
The rest of the week.
Speaker 2 (16:11):
It is said that formerly single vessels have taken away
as many as seven hundred, and that the ship's company
of a frigate some years since brought down in one
day two hundred tortoises to the beach. And this brings
us to a very sad fact about the human use
of tortoises. Here that tortoises were, of course very good
meat sources for sailing vessels, but this was especially due
(16:34):
to the fact that because turtles have a very slow metabolism,
and they could be loaded into the ship alive and
then would survive for an extremely long time without food
or water in the hold. And it's important to remember that,
of course, ships at the time didn't have refrigerators or
freezers or other sophisticated food preservation techniques beyond things like
(16:57):
the nuclear option salting.
Speaker 1 (17:00):
Yeah. Yeah, so this is quite sad to picture, because
on one hand, it's not like these tortoises were wandering
around on deck. They were stuffed below I think generally
upside down and just stored away as living casks of
food because they could live for up to a year
without food or water, which is just crazy to think about,
(17:21):
but also just unimaginately cruel to imagine them down there.
And on top of this, one of the other troublesome
things about this for the tortoises is that the sailors
would tend to grab the tortoises they could easily carry
back to the ship, which meant that they tended to
focus on the smaller tortoises and leave the bigger ones.
This meant that they were favoring female tortoises over male tortoises,
(17:45):
and I guess to a certain extent also younger male tortoises,
but certainly skewing more towards female tortoises, thus destabilizing the
species even more than if they had managed more of
a fifty to fifty split between the tortoise genders.
Speaker 2 (17:57):
Yeah, so unfortunately a lot of tortoises were removed from
the islands that way, but also they just remained a
live meat source for hunting by the locals, and Darwin
tells many interesting stories about this. For example, he writes
about a time that he went up to one of
(18:17):
the highland regions of one of the islands, and he
hung out in a hovel that had been built by
two men there who spent their time hunting tortoises. And
so he visits these guys and he sleeps there in
the hovel one night, and what did he eat while
he was there, Well, exclusively tortoise meat. That was the
entire menu, about which he says, quote the breastplate roasted
(18:41):
as the gauchos do carne conquero, which I think means
meat with leather with the flesh on. It is very good,
and the young tortoises make excellent soup, but otherwise the meat,
to my taste, is indifferent.
Speaker 1 (18:54):
Oh well, there you go. Also taking the harvesting the
young tortoises, that's great as well.
Speaker 2 (18:59):
But they apparently these the adult tortoises, are an amazing
food source because of their immense size, and Darwin recounts
a story told to him by a mister Lawson, who
is an Englishman who is vice governor of the Charles
Island Colony, saying that some tortoises, when caught, required six
to eight men just to lift them off the ground
and would provide up to two hundred pounds of meat.
(19:22):
Darwin also later describes a strange operation performed by the hunters.
He says that you know they didn't always kill a tortoise.
He says that, well, the tortoises meat is used both
fresh and salted. The tortoises are also important for providing oil.
Speaker 4 (19:38):
That's right, reptile lard.
Speaker 2 (19:40):
And oil that I think could be used for food purposes,
but also for just like lamp purposes.
Speaker 1 (19:47):
I believe yeah, it's said that in the old days,
the larger towns of the Galapagos would have their streets
would have been lit with tortoise oil.
Speaker 2 (19:55):
Bizarre though, I guess we're more familiar with that from.
Speaker 4 (19:59):
Like whale oil and stuff.
Speaker 2 (20:01):
But yeah, so if a tortoise will not provide enough oil,
it is apparently not worth killing to the hunters. So
Darwin writes, quote, when a tortoise is caught, the man
makes a slit in the skin near its tail so
as to see inside its body whether the fat under
the dorsal plate is thick. If it's not, the animal
is liberated, and it is said to recover soon from
(20:21):
this strange operation. In order to secure the tortoise, it
is not sufficient to turn them like a turtle, for
they are often able to get.
Speaker 4 (20:29):
On their legs again.
Speaker 2 (20:31):
And I think this is something that will come up later,
because there are some situations where these tortoises often do
end up flipped on their backs, even under natural circumstances,
and they need to be able to flip back over
and get back to business.
Speaker 1 (20:44):
I did not get to see that happen, thankfully. I
don't want to see a tortoise in distress.
Speaker 2 (20:49):
No, we're not going to ask you the quiz from
the blade runner test. So what do these tortoises eat
to grow so big? Well, it turns out in reality,
they just they eat plants. These are entirely herbivorous creatures.
There are turtles and tortoises that eat other things, but
these tortoises are entirely plant eaters. And so especially in
(21:10):
the lowlands, especially the saddlebacked tortoises, will eat succulent cactus.
This is something Darwin identifies. He says they especially favor
the cactus if they live in the low and arid
parts of the islands where there is little or no water.
Of course the cactus becomes a principal water source, but
also they eat tree leaves and berries as well as
(21:32):
green lichen, and their diet somewhat depends on which species
they are and which part of the islands which microclimate
they inhabit. Like the ones that live higher up in
the highlands with more lush vegetation probably feed on more
leafy stuff, and the ones that live more in the
arid regions probably feed on more cactus.
Speaker 1 (21:52):
Yeah, the ones I got to actually observe in the
wild as it were on San Cristobo on Santa Cruz Island.
They they were definitely eating the leafy green stuff. But
I got to see plenty of the cacti, which of
course have coexisted with the tortoises long enough that they
have particular adaptations, like they have been changed by cohabitation
(22:18):
with the tortoise as well. And the most remarkable of
these are the ones that they basically seem to grow
up like trees and then branch out because they're trying
to reach and reaching an optimal height at which they're
hopefully above the reach of the tortoise.
Speaker 2 (22:34):
There is one type of cactus there's a great picture
of in this book by Creature in Laughlin I've been
talking about. It's called a candelabra cactus, and I thought
it was beautiful because the branches look to me like
giant green tarantula legs. They kind of have these lobes
that look like little hairy leg segments on a large spider.
Speaker 1 (22:56):
Yeah. Yeah, And this is a nice picture too, because
you got a flamingo in there. I did get to
see a few flamingos on Seymour Island, I.
Speaker 2 (23:04):
Believe, But the tortoises just generally seem to eat all
kinds of foods that would look to us quite hostile.
So of course the ones in the lowlands are going
to eat a lot of cactus, but they also apparently
eat plenty of poison apple or men's in illo, which
is toxic. It has a sap that is poisonous to
(23:25):
other creatures, and I think it can cause blistering if
you touch it. But apparently the tortoises just chow down
on this stuff, doesn't bother them.
Speaker 1 (23:35):
Yeah. On San Cristobo Island, the area where we were
encountering the tortoises, they had signs everywhere, do not touch
the apples. Do certainly do not eat the apples. Leave
this to the tortoises.
Speaker 2 (23:48):
Now, coming back to Darwin's writing on the tortoises, he
also observes their relationship with water. He says, they are notable,
of course for their ability to survive without water for
a very long time. But when they get out access
to water, they go hog wild. They love it, the
spring water and the mud puddles. They'll just get in
there and settle in, sometimes for days at a.
Speaker 4 (24:10):
Time, and when.
Speaker 2 (24:11):
They're drinking they will just gulp huge mouthfuls of water
for a long time. And Darwin even this leads into
him writing a really bizarre anecdote that I had to share.
So he says, quote for some time after a visit
to the springs, their urinary bladders are distended with fluid
which is said to gradually which is said to gradually
(24:32):
decrease in volume and to become less pure. The inhabitants,
when walking in the lower district and overcome with thirst,
often take advantage of this circumstance and drink the contents
of the bladder if full. In one tortoise I saw killed,
the fluid was quite limpid and had only a very
slightly bitter taste. The inhabitants, however, always first drink the
(24:54):
water in the pericardium, which is the membrane of belief
that surrounding the heart tissue, which described as being best.
So that's right, drinking the water from a tortoise's heart
or from a tortoise's bladder. And Darwin tasted the tortoise
bladder water.
Speaker 1 (25:10):
I guess I should be happy for this, that they're
using all parts of the tortoise conceivably in doing this.
But of course this is still kind of sad to imagine. Yeah,
but also from just a purely anatomical level, this is
of course amazing.
Speaker 2 (25:27):
Now, Darwin goes on to talk about how impressed he
is by the long determined journeys that some of these
tortoises make between He believes what the point of these
journeys is is between highland water sources and usual breeding
grounds in the lower districts. I don't know if that
holds up as the main reason for these journeys today,
(25:50):
though I do think some of these tortoises do make
journeys between the highlands and the lowlands for the purpose
of depositing eggs the females do after mating season. But
there are also journeys I think having to do with
food resources in the different seasons and so forth. But anyway,
Darwin says, you know, although the tortoises are pretty slow
in their movements, you would be surprised how much ground
(26:12):
they cover over time due to sheer determination. He estimates
that they're going to move sixty yards in ten minutes,
which is three hundred and sixty yards in an hour,
or about four miles a day.
Speaker 1 (26:23):
Yeah, it's pretty remarkable, and of course nowadays of course
that everything has been shifted around a bit. You know,
all these invasive species, not only the such harmful invasive
species as pigs and goats that were introduced and then
their populations have been dealt with to varying degrees. But
you also have, of course, have plants to think about,
(26:44):
and so in some cases you have things like berries
that are now grown in the Galapagos and may occur
wild in some cases, and of course the tortoises love
those even though they are not native, and so you
may see that interfere with their movements. So that but yeah,
basically through modern conservation and through modern tracking technology, you
(27:05):
can actually see all of these tortoise movements plotted out
on maps and it's quite impressive. I think they are
movements in these cases help illustrate why they're so crucial
for the island ecosystem that they thrive in. They eat
so much and while they're slow, they do cover a
lot of ground and defecate to spread speeds spread seeds rather,
(27:28):
and this is very much in line with other megafona
that you encounter in other ecosystems as well as the
remember if you think back to our episode on or
episodes on the giant moa bird, which of course is extinct,
but would have we still see like the footprint of
their ecological importance in the areas that they occupied, because
(27:49):
they were vital for consuming plants and then spreading those
seeds through defecation.
Speaker 2 (27:55):
Yeah, there is a great passage in the book by
Creature and Laughlin where they talk about the importance of
the tortoise in spreading a type a species of wild
Galapagos tomato plant, which apparently it only the seeds only
germinate under very specific conditions, such as being exposed to
acid for a long period of time.
Speaker 4 (28:17):
Now, how does that happen, Well.
Speaker 2 (28:18):
It happens in the digestive system of the tortoise. So
like they take this in, the seed gets exposed to
the acid within the digestive juices, and then it gets
it travels with the tortoise a long ways away from
its original location, so that's also good for dispersal. And
then once the tortoise poops it out, it of course
has a bunch of nutritious fecal matter surrounding it to
(28:41):
help it grow.
Speaker 1 (28:42):
Yeah, yeah, I've got I did get to poke some
tortoise dung with a stick. My son and I did,
and we got to look all in there. It's, you know,
quite fascinating. I think some stats would really help drive
home though, why the tortoise is so great at this.
And I got these from Seed Dispersal by Galapagos Tortoises
by Blake at All, published in the Journal of Biogeography
(29:05):
from twenty twelve. So, in this particular survey, the researchers
looked at one hundred and twenty fresh dung piles in
both agricultural and national parkland. They found seeds from more
than forty five plant species in these dung piles, eleven
of which were from introduced species, you know, like various
berries and whatnot. A per tortoise average of four hundred
(29:27):
and sixty four seeds and two point eight species per
dung pile was detected. Now, this is where it gets
kind of interesting, because, okay, we've already established that, yes,
they eat a lot, they travel farther than you might think,
But how long does it take for them to process
their food? Things go a little slower with the Galapagos tortoises.
(29:48):
The mean digesta retention time for a tortoise is twelve days,
but twenty eight day retention times have been reported, so
that's the time time it takes for the food that
they've consumed to process through their body and become dung, so.
Speaker 2 (30:05):
They can really cover some ground in that time.
Speaker 1 (30:07):
Yeah. During that time, according to this paper, the tortoise
may travel between three hundred and ninety four and four
three hundred and fifty five meters on the high end,
that's two point seven miles or four point three kilometers.
Speaker 2 (30:20):
So you can see how these tortoises would play an
incredibly important role in helping the reproduction and dispersal of
local flora.
Speaker 1 (30:28):
Yeah. Absolutely. I mean, as with any species, they don't
they're not existing in isolation in their ecosystem. They have
a roll, they have a place in it. And if
you disrupt them, if you disrupt their numbers, or in
the very worst case scenarios, if their extinction is brought about,
then there is there's something missing. There's a you end
(30:50):
up pulling the carpet out from everything, and unlike with
the parlor trick, all the plates and the dishes are
not necessarily going to stay standing up.
Speaker 2 (31:08):
Now we've been talking about a lot of the predation
and hunting of these tortoises. But barring that, how do
tortoises die?
Speaker 4 (31:17):
What happens?
Speaker 2 (31:18):
Well, Darwin writes, quote the young tortoises as soon as
they are hatched, fall preying great numbers to the carryon
feeding buzzard. I think that would actually be referring probably
to the Galapago's hawk, unless he's talking about some other
species that came in after humans arrived. But and Darwin
goes on, the old ones seemed to die generally from accidents,
(31:41):
as from falling down precipices. At least several of the
inhabitants told me that they never found one dead without
some evident cause, which, oh, that kind of gave me
a shiver.
Speaker 1 (31:53):
Yeah, yeah, I mean, it's just impressive how long they live.
That and I did the first point about P's worth
pointing out that the tortoise sanctuaries that are up and
running now they care for the little ones to protect
them from you know, not only the hawk, but also
all these introduced species that may be about once they
get big enough. Though, Yeah, there's only really three ways
(32:15):
they're going to die old age eventually, accident, vehicular especially
of course being the main threat, though on the Galapico
sidelands today a lot of you know, laws and messaging
have been put in place to prevent this from occurring.
And then of course in the past human hunting was
the big thing.
Speaker 2 (32:36):
Now you mentioned they can die of old age, of
course they do, but that can take.
Speaker 4 (32:39):
A good long while.
Speaker 2 (32:41):
I was reading about this in a Creature in Laughlin
and they say that it's possible, though we have no
way to know for sure, that there may be tortoises
still alive on the islands that were present when Darwin
visited in eighteen thirty five, and a Galopago's tortoise named
Harriet lived to an estimated age of one hundred and
seventy five before she died in an Australian zoo in
(33:04):
two thousand and six, so they can live a long
long time.
Speaker 1 (33:09):
Yeah, I was doing some crunching on this as well.
I think one of the sources I was looking at
had listed like one hundred and seventy one years as
being one of the oldest stage is known for the tortoises.
And even if you're just going to go with that,
if you consider the idea that you have a tortoise
born in eighteen thirty five when Darwin is visiting, if
(33:29):
it lived one hundred and seventy one years, it would
live to the year two thousand and six. Wow, which
is just crazy to think about the idea that just
one tortoise lifetime would bridge our time to the time
of Darwin, and that a single tortoise lifetime could encompass
basically the two worst centuries of the impact of humanity
(33:51):
on Galapago's tortoise numbers as well. Now, again not to
come back too much to the horrors of human tortoise interaction,
but yeah, there are these accounts read too of like
times when roads to various villages were just lined with
like the bones or the shells of these creatures. It
(34:11):
was it was a rough time to be a Galapagos tortoise.
Speaker 2 (34:14):
Yes, no, I now I think it's worth talking about
Galapagos tortoise mating and reproduction, which there's some interesting stuff.
For one thing I was reading about Maybe we can
get to the actual mating in a minute, But first
I was reading a section in Creature in Laughlin about
the nests and egg laying of the Glopagos tortoise. So
(34:38):
mating season typically occurs during the rainy season, and after
having mated, a female tortoise will generally travel toward the
arid lowlands to build a nest. Darwin has a section
about this where he correctly observes that they will seek
out arid sandy soil to dig a nest in, but
then he says others. He says, sometimes they will just
(34:58):
drop their eggs where like in a precipice, like in
a crevice in the rocks. I didn't find any other
evidence of that, so maybe that was true when he
was there, but I'm not aware of other evidence for
that other than what Darwin says. But generally what they
do is they're going to dig down in the arid regions. Now,
for the saddleback tortoises, which tend to live more in
(35:19):
the lowlands, this is not much of a trip. But
for the domed tortoises it can be a really great
journey down from the highlands into the place where they're going.
Speaker 4 (35:27):
To lay the eggs.
Speaker 2 (35:29):
And the eggs are laid sometime between June and December.
A clutch can contain anywhere from like two to twenty eggs.
The eggs are sort of billiard ball sized or maybe
a little bit larger. And the nest building process is
what interested me because apparently it involves a good bit
of pa. So the tortoise will find a spot in
(35:49):
the soil and she will dig a hole about thirty
centimeters deep, scooping the earth out with her hind legs,
and this is an involved process that can take up
to about twelve hours, and the tortoise will often urinate
on the soil in order to soften it for digging.
But the mother tortoise, after she lays her eggs in
the hole and covers it up, then also peas on
(36:11):
the soil again to form a kind of cement layer
in it.
Speaker 1 (36:15):
This is interesting. We've discussed a number of different nest
building egg laying scenarios over the years, but I don't
remember one that was so urine intensive.
Speaker 2 (36:25):
Yeah, there may be other species that do pie cement,
but this is the first time I remember reading about this.
So anyway, the eggs incubate in the cemented earth for
like four to eight months, where the sex of the
hatchling is ultimately determined by the temperature which the egg incubates.
That's kind of interesting. It's not chromosomally determined as it
(36:45):
is for some other animals, and so afterwards they dig
their way out of the nest to begin their lives,
and of course this is the most vulnerable time for
a Galapagos tortoise when they're a hatchling, but the ones
that survived make it out. They find food, they avoid predators,
and they eventually grow up, though apparently the growing up
also takes a good bit of time. The tortoises do
(37:07):
everything pretty slow, including reaching maturity. I've read that they
don't reach sexual maturity until several decades later.
Speaker 1 (37:15):
The mating itself is also kind of interesting because they
basically consists of the males chasing the females around until
they can corner them. But then there's also, given these
are large shelled creatures, the male's shell has like an
indention on the bottom that allows for it to mount
the female, because otherwise, unless there was some arrangement of
(37:39):
the shells in this capacity, that they would not be compatible.
Speaker 2 (37:42):
Right, And there was also a fact I came across
that I thought was funny. In this book, they talk
about how the larger size of the Glopagos tortoise can
make the physical active mating sometimes kind of cumbersome and laborious,
and the authors note that quote, males often slide off,
even inadvertently, landing upside down, at which point they must
(38:03):
right themselves and try again, which I don't know if
it's juvenile that I found that funny, but I did.
The authors also note that the male tortoises sometimes get confused.
For example, they try to mate with large rocks.
Speaker 1 (38:17):
Well, that's just, in and of itself funny. We can't
help but laugh at that.
Speaker 2 (38:21):
But there's also surprising. For these very slow moving animals,
there is some surprisingly fierce competition between males for access
to mates, and Darwin notes this. He says, during breeding season,
you can hear the males emit what he calls a
horse roar. And I think this roar is probably indicative
of male on male competition, which sometimes leads to these
(38:44):
mock fights where they will raise their necks up at
each other. Rob, I think you actually maybe saw one
of these going on.
Speaker 1 (38:51):
Yes, I got to see this happen, and I actually
got to film it. I was able to my wife
was like, quick, get your camera out, make sure you're
getting this. So I did. Yeah, it's amazing to watch
because you'll have these two lumbering giants that are kind
of on a collision course with each other, and you're like,
what's going to happen, what's going to happen? And then
as they get closer, they'll both rear their heads up
(39:14):
and they'll have this showdown that doesn't it does not
come to blows or bites or anything like that, but
it is a competition to see who to determine who
is the tallest and the tallest tortoise, who had the
one that can raise its head up the highest, he's
the winner, and the other one accepts defeat and carries on.
And that's as violent as it seems to get. But
(39:35):
it's spectacular to watch. And this was the finest nature
footage I have ever captured or will ever capture.
Speaker 2 (39:42):
Now, one last thing I wanted to read from Darwin
here where he's talking about the tortoise's reaction to humans.
This is another infamous section from the Voyage of the
Beagle chapter. Darwin says, I was always amused when overtaking
one of these great monsters as it was quietly pacing along,
to see how suddenly the instant I passed it would
draw in its head and legs and uttering a deep hiss,
(40:05):
fall to the ground with a heavy sound, as if
struck dead. I frequently got on their backs and then
giving a few wraps on the hinder part of the shells,
they would rise up and walk away, but I found
it very difficult to keep my balance.
Speaker 1 (40:20):
Oh, Charles, no doing, Why are you riding a tortoise?
I mean it is kind of I mean it based
on this account, the tortoise is doing exactly what you
know I observed, and all these sources say they do
if someone gets too close or something gets too close.
But it is kind of interesting this added detail that
(40:41):
apparently eventually the tortoise is like, Okay, I guess this
weird British man is not going away. I have things
to do in places to be I'm just going to
start walking around with him on there and maybe I
can sort of shake him off.
Speaker 2 (40:53):
Yeah, and this is actually not an isolated report. Again,
we are not recommending riding the tortoises, and other other
people talk about how well you can get on their
backs and ride them and they'll just go about their business.
And this is apparently a common occurrence. There was a
common occurrence.
Speaker 4 (41:09):
Back in the day.
Speaker 2 (41:10):
Sometimes they say, you can get two people on one
of these tortoise shells and just ride them and they'll
do their thing, like you know, they don't seem they
don't seem bothered. Now, I'm sure that puts extra strain
on their muscles and their energy requirements and all that.
So it's not like okay to do. But just showing
the strength of the tortoise and how powerful and huge
this animal is that it could just continue on its
(41:32):
way trying to graze with like multiple humans riding on
its back.
Speaker 1 (41:36):
Oh, poor creatures. Yeah, again, do not attempt to don't
do not get close to the tortoises, and do not
ride them. Now, we have a fair amount of variety
with the Glapygos tortoises that they're all of the genus Chellinitis,
and you get into some discussion about the different varieties
(41:57):
like the exact variety count. And then we have two
that are definitely extinct. There's the Floriana Island subspecies that's
thought to have been hunted to extinction by I think
eighteen fifty when Darwin visited. This is I believe the
one where he only describes seeing their bones. The Pina
(42:17):
Island species is extinct as of twenty twelve, with the
death of Lonesome George, who was of course famous for
being the last of his variety. He died and that
was seemingly it for this variety of tortoise.
Speaker 4 (42:31):
Yeah.
Speaker 2 (42:32):
I've read that there are either twelve or thirteen extant species.
Speaker 1 (42:38):
Yeah. So, coming back to the challenges that tortoises faced
during the age of humans, we've thoroughly discussed. I think
the human hunting and human harvesting of tortoises, at least
(42:59):
for our purpose, is here. But of course there are
all these invasive species that humans introduced, and while we
are dealing with cases in some cases where you'll have
animals directly going after young tortoises, there are also other
ways that these creatures were harmful and are and can
still be harmful to the native Galapagos tortoises.
Speaker 2 (43:23):
Right, And in fact, one example of this came up
in some episodes we did back in October on goats, right,
the issue of goats competing for resources with tortoises.
Speaker 1 (43:32):
That's right again. Goats, as we discussed, are amazing at
what they do at roaming around finding odd bits of
vegetation to consume, and yeah, they're they're ultimately better at
it than tortoises. They're more thorough than the tortoises, and
ultimately so thorough that they can be even more disruptive
to like the to the ground itself, like you know,
(43:56):
getting in there and actually making it unstable. So that's
that's one thing to consider. Also when you're dealing with
any creature that lays its eggs in the ground. Not
only do you have to worry with certain species, like
especially pigs and rats going after those eggs and then
going after the young. Potentially, you also have to deal
with cattle because there are still cattle on the islands,
(44:18):
and cattle were brought to the islands, and cattle aren't
interested in really eating those tortoise eggs, but they will
definitely step on those tortoise eggs if they happen to
be ranging in the same area.
Speaker 2 (44:28):
Now, in the previous episode, we talked about some hypotheses
about how marine iguanas first arrived on the Galapagos Islands,
probably via some kind of rafting from the mainland. Is
that also the idea of what likely happened with the
ancestral tortoises.
Speaker 1 (44:46):
That's my understanding based on the sources I was looking at,
and based on conversations with some of the naturalist and
guides in the Galapagos Islands. The idea is that it
would have been much the same tortoises in South America,
swept up in river floods, washed out with vegetation which
they were able to raft on, and reaching these far
(45:09):
flung islands.
Speaker 2 (45:10):
So it's amazing to imagine these extremely unlikely, kind of
one off events that allowed the population of each island,
because it's not something you see happening every day. But
you know, all it takes is a is a small
seed population to get there and then wow, what's this.
You know, there's all these food resources and no predators
and you can really boom once you arrive.
Speaker 1 (45:32):
Yeah. And I'm not sure if the numbers on this
are you know, certified as it were, but it seems
like the first Glapacos tortoises probably reached the islands two
to three million years ago via rafting. They would have
probably arrived on the eastern islands of Espanola and San
Cristobile first and then spread west from there. So it's yeah,
(45:57):
it's interesting to think about. Now. The other question that
I guess came up for me, and this was like,
how big were these tortoises when they first arrived, because
at least some sources out there make the case that
they were already big, that they were already quote unquote gigantic,
while plenty of other sources also discuss Glapago's tortoises as
(46:19):
a case of island gigantism.
Speaker 2 (46:21):
Yeah, so island gigantism is something that often occurs. There's
known as island dwarfism and island gigantism. These kind of
runaway pressures on the size of animals that can really
bulk them up or shrink them down when they're in
a contained ecosystem like an island. And I don't think
(46:42):
we know exactly what all the pressures would be, but
you could imagine something like, well, maybe there is always
sexual selection on, say the size of adult male tortoises,
to make them bigger and bigger, because the bigger you are,
the more likely a female is to be receptive to mating.
So there's a sexual selection driving them to be bigger.
But then there's naturally some kind of other pressure that
(47:03):
wants to keep their size smaller. You know, like you
there's that advantage in being bigger. But once you're bigger,
maybe you're more at risk of predation, or it's harder
to thermoregulate or something like that. And you can imagine
cases where you get on an island and suddenly those
other pressures are relieved and so you can just keep
getting bigger and bigger than you would have been allowed
(47:23):
to on the mainland.
Speaker 3 (47:25):
Yeah.
Speaker 1 (47:25):
Yeah, I guess on the like supporting the idea that
they were already big there is. There is, of course,
fossil evidence of gigantic tortoises existing on I think every
continent except Australia and Antarctica at some point in the past,
so it's not like these forms only emerged on various
(47:47):
islands island environments. But I don't know. On the other hand,
it seems like plenty of sources are discussing this as gigantism.
One paper I was looking at this is from Jaffe
at All, from a twenty eleven paper in the Royal
Society Biology Letters, The Evolution of Island gigantism and body
size variation in Tortoises and turtles. They point out that
(48:08):
they do point out that quote, the other evolutionary determinants
of size diversity in Chilonians are poorly understood. But they
also point out that Chelonians span some four orders of
magnitude in their sizes, and that there is quote a
pronounced relationship between habitat and optimal body size. Also worth
noting that the apparently the closest living relative to the
(48:30):
Galapagos tortoise is not a direct ancestor of those tortoises,
but it is itself a relatively small bodied variety of
tortoise that's found in South America, the Chaco tortoise, I
believe it is called now. I also mentioned that there
are other giant tortoises still in the world outside of
the Galapagos. These would be giant tortoises that survived in
(48:54):
the Western Indian Ocean in the form of Aldabra giant
tortoises leave.
Speaker 2 (49:00):
When Darwin arrived, he thought that these were the same species,
like that the ones on the Galapagos were the same
as those, or at least the same as some other
island gigantic tortoise he was aware of. I think it
would have been those, because those are the only other
ones I know of, and he was mistaken in that
in fact that they're just they're different parallel forms of
(49:21):
gigantic tortoises. But one last thing I wanted to talk
about with these tortoises before we wrap up today is
the differences in the shell shapes, because we mentioned earlier
that some species have more dome shaped shells and some
have these saddle shaped shells, and there are also intermediate
(49:42):
species that have sort of somewhere in between. A creature
and Laughlin have a great section on this in their
chapter on the tortoises, and I wanted to talk about
it a bit. So one of the questions is why
you can observe some things that might lead to these differences.
The tortoises with the domed shells tend to live more
(50:03):
in the highlands and around caldera rims, where vegetation is
much thicker and lush all the time, whereas the ones
with the saddle backed shells tend to live more or
even exclusively in the low lands, where conditions are more
often dry. Of course, the differences in these shells is
that while as the domed ones are more just kind
(50:24):
of like an upturned cup over the reptiles back. The
saddleback tortoises, their shell tends to have like a relief
area above the head and neck. It's almost like a
collar that's pulled back. And there are some other differences too.
The domed tortoises tend to have a larger body size,
but shorter legs and necks, whereas the saddleback tortoises tend
(50:47):
to be smaller overall but have longer legs and longer necks.
Speaker 4 (50:52):
Now, remember in the.
Speaker 2 (50:53):
Last episode when we talked about the marine iguanas and
we were trying to come up with the biological explanation
for why the iguana kept returning out of the water
after Darwin threw it in, even though you know it's
got to go in the water all the time to eat,
So why doesn't it just stay in the water to
stay away from him? And the answer we came up
(51:15):
with that the Darwin did not land on himself is
that it's probably for thermoregulation reasons because the water is
cold and it was removing heat from the iguana's body
and the iguana needs to get back up on land
to heat back up. I think a good explanation for
One of the explanations for the different body plans of
(51:37):
these different tortoises probably also has to do with reptile
thermoregulation with the regulation of body temperature, because of course,
animals with a larger body volume also tend to retain
more heat because they have less surface area proportional to
their volume. So if you're living in a cold place
(52:00):
and you're trying to retain body heat, it's easier to
do that if you're bigger. You've got there's just more
body in there and less relatively less surface area, and
vice versa. It's easier to cool off if you're smaller,
because a bigger percent of your body is surface area
that you can lose heat through. This would seem to
correlate with the observation that the domed tortoises, which live
(52:24):
up in the highlands where it tends to be a
little bit cooler, tend to have a larger body size
but also shorter legs and necks, so less extremities poking
out that can lose heat, whereas the saddleback tortoises tend
to be smaller overall, with longer legs and longer necks
and they live down in the lowlands where things tend
to be hotter.
Speaker 4 (52:45):
Yeah.
Speaker 1 (52:46):
Yeah, Now, most of the tortoises I got to observe
were definitely in highland environments, but their relationship with temperature
is notable as well. In one case, we've got to
go out and see these tortoises out there in this
this this this highland area, and it was early enough
(53:06):
in the day that some of them were essentially sleeping in.
They were still bedded down in the mud where they
could they could, you know, keep their temperature relatively stable
throughout the night. And some were already getting up to
begin their their day of eating. Others just weren't quite
ready yet.
Speaker 2 (53:22):
Oh yeah, And I've read that these tortoises just love
the mud, like they'll love to get in the mud
puddles and they'll just hang out there for days sometimes.
Speaker 1 (53:30):
Yeah, so you'll see them trooping around and yeah, on
one level, they kind of look like bulldozers because they're
just covered with mud, and of course they've been eating too.
There are lots of pictures you included one here of
one with just this spectacularly messy's face from all the
vegetation and or fruits it's been consumed. It's just smeared
all over.
Speaker 2 (53:48):
It's like one of those gross baby pictures where the
baby just looks they've been face down in a play
of spaghetti.
Speaker 1 (53:54):
Yeah, and their face, the face of the Glabgos tortoise
does kind of look like like old baby, so it
really matches up with that well.
Speaker 2 (54:03):
But there are other differences in the environments that might
explain the different body plans of these tortoise species, So
a lot of it probably has to do with vegetation.
Speaker 4 (54:14):
Right.
Speaker 2 (54:15):
Domed tortoises tend to live in more lush highlands with
dense undergrowth and a creature in Laughlin right quote. The
domed shells, smoothly rounded as they are, may prove adaptive.
Is the tortoises move tank like through dense plant cover,
which is of course also the animal's food source. On
(54:35):
the other hand, saddle type shells with a large forward
notch can actually become snagged in low vegetation, impeding the
movement of the tortoise. Saddle shells are not very adaptive
in low dense vegetation, so it's just going to be
easier to move around with a more rounded shell. In
all that thick brush in the Upper Highland forest regions,
(54:57):
whereas if you had the saddle shell with the turned
sort of collar in the front, Yeah, they'd just be
getting hooked on stuff all the time.
Speaker 1 (55:04):
And I mean they are little bulldozers. They can tear
stuff up. Like for instance, you know there are gonna
be limits. They could continue, you know, be slowed down
or I guess stuck in vegetation. But to give one
example that I was told about, do you have again
individuals who are still ranching in these in these parts
of the Highland, they have cows. They need to contain
(55:26):
those cows. But if they're gonna be tortoises moving through,
they're gonna they're just gonna take down your barbed wire
fence or your your whatever kind of fencing you have.
So in many cases they'll have the fencing, they'll have
this big gap at the bottom that will allow a
tortoise to move through, because that way you still get
to have your fence and the tortoise won't won't tear
it down when it makes a bee line for whatever
(55:48):
wherever it's going.
Speaker 2 (55:49):
Yeah, fortunately the cows can't crawl under Yeah.
Speaker 1 (55:52):
I guess not. It did raise some questions like, well, yeah,
can the cow what about really short cows? I don't know,
but apparently it works.
Speaker 2 (56:01):
But the final thing with the difference between the domed
tortoises and the saddlebacks is probably food sources as well,
because again, the domed ones are going to be munching
on a lot of you know, lush, low lying vegetation,
so you know, that's just that's okay to have a
normal kind of dome dome shaped shell for that. But
(56:23):
the saddleback tortoises, which live in the more arid lowlands,
are going to be eating cacti, often tall cacti that
they need to reach up to get to, and so
the upturned front of the shell allows more room to
raise the neck, and of course, of course, as I
said as well, they've got longer necks and longer legs
to help reach Robin, I think you said you observe
(56:46):
stuff about those cactuses sort of reacting to that by
growing taller and taller to try to escape the munching tortoises.
Speaker 1 (56:54):
Yeah. Yeah, And it's it's remarkable to see because yeah,
here's this, here's this cac that has evolved to thrive
alongside the tortoises, and it ends up, Yeah, it ends
up feeling more like a tree than a cactus, if
that makes sense. Yeah, it's a remarkable ecosystem.
Speaker 4 (57:12):
All right.
Speaker 1 (57:12):
So there you have it. Hopefully we gave just at
least a nice snapshot, a nice overview of the Galapagos tortoise. Obviously,
there's a lot of research out there about these creatures,
so perhaps there's some details that we managed to leave out.
If you think that we left out something that is
particularly exciting, then right in. We'd love to hear about it.
(57:33):
We'd love to see it for ourselves and to share
it in a future listener mail. Likewise, as I mentioned
the first one, if you've traveled with the Glabgos Islands,
if you live on the Galapagos Islands or are an Ecuadorian,
we would also love to hear from you. We love
your thoughts on these fabulous creatures that we've discussed here,
or any of the other creatures of the Glabgos Islence,
(57:54):
I'm always excited to hear more. Just a reminder to
everybody's Stuff to blow your mind. Publishes us it's core
episodes on Tuesdays and Thursdays. In the Stuff to Blow
Your Mind podcast feed we have listener mail episodes on Mondays,
a short form artifact or monster fact episode on Wednesdays,
and on Fridays we set aside most serious concerns and
just talk about a weird film.
Speaker 2 (58:15):
Huge thanks to our audio producer, Max Williams. If you
would like to get in touch with this with this podcast,
with us with feedback in response to this episode or
any other, with a suggestion for a future episode topic,
or just to say hello, you can email us at
contact at stuff to Blow your Mind dot com.
Speaker 3 (58:43):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my Heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you're listening to your favorite shows.
Plates rat late ratt
Hey you welcome to Stuff to Blow Your Mind. My
name is Robert.
Speaker 2 (00:09):
Lamb and I am Joe McCormick, and today we're bringing
you an episode from the vault. This is part two
of our series on the reptiles of the Galapagos. This
was originally published December tenth, twenty twenty two.
Speaker 3 (00:20):
Enjoy Welcome to Stuff to Blow Your Mind, production of iHeartRadio.
Speaker 1 (00:34):
Hey, welcome to Stuff to Blow your Mind. My name
is Robert.
Speaker 2 (00:37):
Lamb and I'm Joe McCormick, and we're back with part
two of our series on the reptiles of the Galapagos Islands. Now,
in the previous episode, we focused mainly on the marine iguana,
or as they were often referred to early on, those
hideous creatures, those stupid, awful, sluggish lizards. We mounted a
(00:58):
defense of the marine iguana. But today we are here
to talk about the Galapagos tortoise. And I wanted to
kick things off by reading a passage from Charles Darwin
in the Voyage of the Beagle. Darwin, of course, was
not just a great scientist, but a really wonderful writer,
and I think this will help set the scene. So
(01:19):
are you ready to hear about Darwin's first vision of
San Cristobal Island. Then then what they called Chatham Island.
Speaker 1 (01:27):
Yeah, let's let's hear from from old Charles.
Speaker 2 (01:29):
And this is part of a narrative of when he
slept ashore one night on the island. So off the boat,
Darwin writes. The entire surface of this part of the
island seems to have been permeated like a sieve by
the subterranean vapors. Here and there the lava, whilstsoft, has
been blown into great bubbles, and in other parts the
(01:52):
tops of caverns similarly formed have fallen in, leaving circular
pits with steep sides. From the regular form of the
many craters. They gave to the country an artificial appearance
which vividly reminded me of those parts of Staffordshire, where
the great iron foundries are most numerous. The day was
(02:12):
growing hot, and the scrambling over the rough surface and
through the intricate thickets was very fatiguing, but I was
well repaid by the strange Cyclopean scene. As I was
walking along, I met two large tortoises, each of which
must have weighed at least two hundred pounds. One was
eating a piece of cactus, and as I approached, it
(02:35):
stared at me and slowly walked away.
Speaker 4 (02:37):
The other gave a.
Speaker 2 (02:39):
Deep hiss and drew in its head. These huge reptiles,
surrounded by the black lava, the leafless shrubs and large
cacti seemed to my fancy like some Antediluvian animals. The
few dull colored birds cared no more for me than
they did for the great tortoises. So Darwin transported to
(03:01):
a time from before Noah's flood by the vision of
these bizarre, gigantic tortoises crawling around on the on the lava.
Speaker 1 (03:11):
Yes, this is the great sceni paints here and and yeah.
As I mentioned in the first episode, I was. I
was fortunate enough to get to travel to the Galapagos
Islands just a couple of months ago. In San Cristobo
Island was one of the islands that I got to visit,
and this was pretty much the the experience I had
with my family walking through one of the the areas
(03:33):
they had set aside for these magnificent tortoises. They're just
they just they walk around as if yeah, if you
don't matter, unless you get a little too close for
their liking, in which case there'll often be this hiss
and this retraction of their head. I mean, their heads
don't retract in the same way that say, a box
turtle does, but they're able to sort of pull their
(03:54):
head in a bit. But that the hissing that Darwin
is describing here, it does have a very, I don't know,
pneumatic kind of quality to it. It feels it sounds
like some sort of machinery. And indeed, that's that's kind
of more what it is, as opposed to like the
hiss you might hear from a house cat or something.
And one of the things that I kept thinking about
(04:16):
while encountering them is that they already move with this
kind of herky jerky kind of locomotion. They already move
like they are elaborate mechanical creatures created for practical effects
for a nineteen nineties science fiction feature. And then they
(04:36):
also make this hissing sound to move part of their anatomy.
So it almost creates this feeling of am I seeing
real animals or is this an elaborate hoax these animatronics? Yeah, yeah, yeah,
they feel almost like animatronics, but of course they're they're
they're they're quite alive, and they're quite, but that's part
of their strangeness, and they just the awe of watching
(04:57):
these giant creatures walk arou around, slowly, eat, and occasionally
have some startling interactions.
Speaker 2 (05:04):
Now I'm greatly envious of the opportunity you got to
see these animals in person, but I trust that you
did not do what Darwin did upon encountering these beasts
and try to ride them.
Speaker 1 (05:17):
Absolutely not, no, no. The only time the times we
were forced to get uncomfortably close in one of these
situations of the area that we were walking through had
a path and you're supposed to stay on the path
and keep your distance from the tortoises. Sometimes though the
tortoises will just get on the path. You have to
find your way around them, and they don't necessarily like that.
(05:40):
But we kept our distance, and you want to keep
your distance because, yeah, if you get a little too close,
they're going to stop interacting with their environment for a
little bit. And if you don't want to watch that,
you want to watch them eat and rampage around and
occasionally have these fabulous stare downs between two males which
(06:01):
I don't know, we may describe this later, So maybe
I shouldn't get into that just yet.
Speaker 2 (06:04):
Yeah, yeah, we can talk about the mock fights later on.
So the Galapagos tortoise is I think you would say,
originally the dominant land herbivore of the Galapagos Islands, which
makes them kind of unique because there's pretty much nowhere
else on Earth now where the dominant land herbivore is
(06:25):
a reptile. So these are very unique and beautiful creatures,
and the Glapagos tortoise stands out so much among the
endemic fauna that it's actually the origin of the archipelago's
name in one way or another. There's a little bit
of nitpicking on that, but basically it goes like this.
By the fifteen seventies, these islands had already appeared on
(06:48):
at least a couple of European maps. The one I
saw named was by a Flemish cartographer named Abraham Ortelius,
and it named the islands Insulae de los galapago or
meaning Islands of the Tortoises. Now, the nitpicking about the
terminology I've read is what exactly the word galapago or
(07:09):
Galapagos originally meant. According to a book that I'm going
to reference multiple times in this episode, Galapagos and Natural History,
second Edition by John Creecher and Kevin Laughlin from Princeton
University Press. That editions out just twenty twenty two. They
write that the origin of the name of the islands
is an old Spanish word, galapago, which was a name
(07:33):
for a specific type of saddle. So there's like, you know,
a saddle you'd use on a horse. I guess that
has a kind of upturned front. That was a galapago.
And some, but not all, of the Galapagos tortoises have
saddle shaped shells. Others have a more straightforward dome. And
we can talk about the evolutionary reasons for those differences
(07:53):
later on. But when Tamas de Berlanga landed on the
islands in fifteen thirty five, a story we talked about
in the previous episode. After this, he wrote a letter
to the king in which he observed describing the animals
of the island, he observed mucos lobos marinos meaning many
sea lions, tortugas meaning sea turtles, iguanas, and Galapagos, and
(08:17):
the authors write that this is probably a reference to
the tortoises and their saddle shaped shells rather than to
literal saddles being on the island.
Speaker 1 (08:26):
This is a solid observation that thankfully still holds true today.
Mucos lobos marinos and tortugas, iguanas and tortoises. Yes, yeah,
the sea lion, I mean the mucco lobos marinos. That
was probably the most astounding of all when you're near
the coast, because they're everywhere and sometimes laying. There'll be
(08:47):
like a male that's come up and he's like laying
in the street, or they they love park benches. There
are a lot of fun to wide.
Speaker 4 (08:54):
Well.
Speaker 2 (08:55):
The difference in the Spanish name. I guess if it's
lobo marino that would mean see wolf, not sea lion, right,
But that that heightens the kind of implicit comedy of
naming these animals after what you would think of as
a more actively voracious land predator, whereas you know, I
guess when they're on the land, they're not quite so
threatening as maybe a wolf for a lion would seem.
Speaker 1 (09:16):
Yeah, I mean, well, on one hand, yeah, you have
some of the little tiny islands are at least one
that's named for the wolves for the lobos, and of
course that's why, because sea lions are hanging out there
and yeah, on the on the on the beach. They're
often quite docile and you see people getting way too
close to them in some cases. But the big males,
of course, are very territorial about hanging on to their
(09:38):
bit of property and their and their females, you know,
their their their beach real estate, and so there of
course always they're continuously loudly sending the alarm and occasionally
chasing off other males. So there's there's a lot of
drama if you just sit back and watch the sea lions.
And I imagine that listeners from other parts of the
(09:59):
world can to this as well.
Speaker 2 (10:01):
Yes, yes, keep your distance, folks, I mean, observe, but
there's no reason to get in the sea lion space.
Speaker 1 (10:08):
Though sometimes in my experience, sea lion will come for
your space. I was just seated away from sea lions
and then here comes this female and she's just howling
about something and insists on taking my spot on a log,
and I'm like, it's yours at yours, and then she
just hangs out on the log for a few minutes
and then leaves it. I don't know, She's just trying
to make a point.
Speaker 2 (10:30):
So if you have never seen the Galopagos tortoises before,
you can easily find lots of pictures of them. But
to briefly describe the adults, there are many different species
scattered across the different islands. Maybe we can get into
the exact numbers on that in a bit, but generally
what they all have in common is that they're very large.
They have large shells, some species with rounded dome tops,
(10:53):
others with the saddle shape that Burlonga probably observed, which
are typically turned up in the front to have a
kind of big notch above the animal's head and neck.
They have long, dry, wrinkly necks which are surprisingly slim,
almost I dare say snake like in a way. They
(11:13):
have blunt, round snouts and a beak like mouth with
no teeth, and everywhere you can see their their skin.
In between the shell parts there is typically a lot
of leathery, wrinkly flesh, which just makes them look like
old people.
Speaker 1 (11:30):
Yeah, they they have this kind of appearance of a
of acute shriveled old person.
Speaker 4 (11:35):
Vase.
Speaker 1 (11:36):
Uh. They're they're very They're very sweet to look at
it's it's it's kind of hard to to not anthropomorphize
them as such even and and that can, of course,
can become complicated when you start considering like the full
range of their of their lifestyle and the way that
they they live and reproduce and so forth. Uh, it
never pays to anthropomorphize creatures too much.
Speaker 4 (11:59):
Yeah.
Speaker 2 (11:59):
Now, no one thing many of us today might not appreciate,
even if you go to the Galapagos today or if
you see Good Nature documentary footage from there, is how
many tortoises there were when people first arrive, Before the
animals had any natural predators other than the threat post
to hatchlings by the Galapagos Hulk, this place was swarming
(12:22):
with tortoises. And to try to get a picture of that,
I wanted to cite some basically math work that Creature
and Laughlin do in their book. So they're talking about
the reproductive rates of these tortoises. So they say, if
a female tortoise has more than two young that survive
(12:43):
into adulthood, the tortoise population will grow, so she has
replaced both her and her mate. And if she has
more than one, the population will grow and they say, Now,
consider that a female tortoise may conservatively lay five to
ten eggs annually for perhaps eighty years or more. So,
(13:04):
just for a very conservative estimate, they say, Okay, imagine
she averages one annual clutch and there's just three eggs
in it. That's kind of a small estimate. But there's
just three eggs per clutch. That's more than two hundred
eggs in a single adult female tortoises lifetime. They say, realistically,
the number is probably a multiple of that. So they're
(13:24):
going to have a lot of young and there before
humans arrive and bring their invasive species with them, before
they bring dogs and pigs and stuff. There is not
significant predation at any life cycle. A part of the
life cycle of a tortoise. There's some minor predation by
like hawks of the babies, but most of them are
(13:45):
going to grow and become reproducing adults.
Speaker 1 (13:49):
Yeah, it's pretty amazing. Amazing. I ask one of the
guides about, you know, how long are the females reproductive?
Because you see some very who was pointed that My
guide here was pointing out the various the old tortoises.
But because you can sort of tell by looking at
their shells the way that the line, like, for a while,
you can sort of it's not like you can count
the rings exactly, but you can sort of see the
(14:11):
rings and the patterns on their shell. But eventually there's
kind of like a smoothing out that occurs, and those
are the really old ones. And the guy was like, yeah,
we're not entirely sure, but it seems like they're reproductively
active for pretty much most of their lives, which is
the astounding.
Speaker 2 (14:38):
Yeah, it's amazing. And so the authors of this book
end up concluding that before humans arrived and brought these
invasive predators with them and started harvesting the tortoises themselves,
which is a sad fact we'll talk about in a moment,
the tortoises.
Speaker 4 (14:54):
Were just.
Speaker 2 (14:56):
Profuse.
Speaker 4 (14:57):
They were everywhere.
Speaker 2 (14:58):
They say, there's a conserva estimate of a total population
of two hundred and fifty thousand tortoises just on this
small group of islands. But of course, today all of
these tortoise populations are at least vulnerable, and some are
up to critically endangered, and that's after a significant bounce
back in some cases, you know, after conservation efforts kicked in.
(15:22):
So what happened to these tortoises. Well, one thing that
happened is is something Darwin talks about in his Passage
and Voyage of the Beagle. Before he even really gets
to ecological observations about the tortoises, he writes at length
about people eating them. So, in describing the small human
(15:43):
colony on what was then Charles Island what today is
called Floriana Island, so Darwin writes, in the woods there
are many wild pigs and goats. Now remember those are
not native to the islands, but introduced by humans. Darwin
goes on, But the staple article of animal food is
supplied by the tortoises. Their numbers have of course been
(16:04):
greatly reduced in this island, but the people yet count
on two days hunting, giving them food for.
Speaker 4 (16:09):
The rest of the week.
Speaker 2 (16:11):
It is said that formerly single vessels have taken away
as many as seven hundred, and that the ship's company
of a frigate some years since brought down in one
day two hundred tortoises to the beach. And this brings
us to a very sad fact about the human use
of tortoises. Here that tortoises were, of course very good
meat sources for sailing vessels, but this was especially due
(16:34):
to the fact that because turtles have a very slow metabolism,
and they could be loaded into the ship alive and
then would survive for an extremely long time without food
or water in the hold. And it's important to remember that,
of course, ships at the time didn't have refrigerators or
freezers or other sophisticated food preservation techniques beyond things like
(16:57):
the nuclear option salting.
Speaker 1 (17:00):
Yeah. Yeah, so this is quite sad to picture, because
on one hand, it's not like these tortoises were wandering
around on deck. They were stuffed below I think generally
upside down and just stored away as living casks of
food because they could live for up to a year
without food or water, which is just crazy to think about,
(17:21):
but also just unimaginately cruel to imagine them down there.
And on top of this, one of the other troublesome
things about this for the tortoises is that the sailors
would tend to grab the tortoises they could easily carry
back to the ship, which meant that they tended to
focus on the smaller tortoises and leave the bigger ones.
This meant that they were favoring female tortoises over male tortoises,
(17:45):
and I guess to a certain extent also younger male tortoises,
but certainly skewing more towards female tortoises, thus destabilizing the
species even more than if they had managed more of
a fifty to fifty split between the tortoise genders.
Speaker 2 (17:57):
Yeah, so unfortunately a lot of tortoises were removed from
the islands that way, but also they just remained a
live meat source for hunting by the locals, and Darwin
tells many interesting stories about this. For example, he writes
about a time that he went up to one of
(18:17):
the highland regions of one of the islands, and he
hung out in a hovel that had been built by
two men there who spent their time hunting tortoises. And
so he visits these guys and he sleeps there in
the hovel one night, and what did he eat while
he was there, Well, exclusively tortoise meat. That was the
entire menu, about which he says, quote the breastplate roasted
(18:41):
as the gauchos do carne conquero, which I think means
meat with leather with the flesh on. It is very good,
and the young tortoises make excellent soup, but otherwise the meat,
to my taste, is indifferent.
Speaker 1 (18:54):
Oh well, there you go. Also taking the harvesting the
young tortoises, that's great as well.
Speaker 2 (18:59):
But they apparently these the adult tortoises, are an amazing
food source because of their immense size, and Darwin recounts
a story told to him by a mister Lawson, who
is an Englishman who is vice governor of the Charles
Island Colony, saying that some tortoises, when caught, required six
to eight men just to lift them off the ground
and would provide up to two hundred pounds of meat.
(19:22):
Darwin also later describes a strange operation performed by the hunters.
He says that you know they didn't always kill a tortoise.
He says that, well, the tortoises meat is used both
fresh and salted. The tortoises are also important for providing oil.
Speaker 4 (19:38):
That's right, reptile lard.
Speaker 2 (19:40):
And oil that I think could be used for food purposes,
but also for just like lamp purposes.
Speaker 1 (19:47):
I believe yeah, it's said that in the old days,
the larger towns of the Galapagos would have their streets
would have been lit with tortoise oil.
Speaker 2 (19:55):
Bizarre though, I guess we're more familiar with that from.
Speaker 4 (19:59):
Like whale oil and stuff.
Speaker 2 (20:01):
But yeah, so if a tortoise will not provide enough oil,
it is apparently not worth killing to the hunters. So
Darwin writes, quote, when a tortoise is caught, the man
makes a slit in the skin near its tail so
as to see inside its body whether the fat under
the dorsal plate is thick. If it's not, the animal
is liberated, and it is said to recover soon from
(20:21):
this strange operation. In order to secure the tortoise, it
is not sufficient to turn them like a turtle, for
they are often able to get.
Speaker 4 (20:29):
On their legs again.
Speaker 2 (20:31):
And I think this is something that will come up later,
because there are some situations where these tortoises often do
end up flipped on their backs, even under natural circumstances,
and they need to be able to flip back over
and get back to business.
Speaker 1 (20:44):
I did not get to see that happen, thankfully. I
don't want to see a tortoise in distress.
Speaker 2 (20:49):
No, we're not going to ask you the quiz from
the blade runner test. So what do these tortoises eat
to grow so big? Well, it turns out in reality,
they just they eat plants. These are entirely herbivorous creatures.
There are turtles and tortoises that eat other things, but
these tortoises are entirely plant eaters. And so especially in
(21:10):
the lowlands, especially the saddlebacked tortoises, will eat succulent cactus.
This is something Darwin identifies. He says they especially favor
the cactus if they live in the low and arid
parts of the islands where there is little or no water.
Of course the cactus becomes a principal water source, but
also they eat tree leaves and berries as well as
(21:32):
green lichen, and their diet somewhat depends on which species
they are and which part of the islands which microclimate
they inhabit. Like the ones that live higher up in
the highlands with more lush vegetation probably feed on more
leafy stuff, and the ones that live more in the
arid regions probably feed on more cactus.
Speaker 1 (21:52):
Yeah, the ones I got to actually observe in the
wild as it were on San Cristobo on Santa Cruz Island.
They they were definitely eating the leafy green stuff. But
I got to see plenty of the cacti, which of
course have coexisted with the tortoises long enough that they
have particular adaptations, like they have been changed by cohabitation
(22:18):
with the tortoise as well. And the most remarkable of
these are the ones that they basically seem to grow
up like trees and then branch out because they're trying
to reach and reaching an optimal height at which they're
hopefully above the reach of the tortoise.
Speaker 2 (22:34):
There is one type of cactus there's a great picture
of in this book by Creature in Laughlin I've been
talking about. It's called a candelabra cactus, and I thought
it was beautiful because the branches look to me like
giant green tarantula legs. They kind of have these lobes
that look like little hairy leg segments on a large spider.
Speaker 1 (22:56):
Yeah. Yeah, And this is a nice picture too, because
you got a flamingo in there. I did get to
see a few flamingos on Seymour Island, I.
Speaker 2 (23:04):
Believe, But the tortoises just generally seem to eat all
kinds of foods that would look to us quite hostile.
So of course the ones in the lowlands are going
to eat a lot of cactus, but they also apparently
eat plenty of poison apple or men's in illo, which
is toxic. It has a sap that is poisonous to
(23:25):
other creatures, and I think it can cause blistering if
you touch it. But apparently the tortoises just chow down
on this stuff, doesn't bother them.
Speaker 1 (23:35):
Yeah. On San Cristobo Island, the area where we were
encountering the tortoises, they had signs everywhere, do not touch
the apples. Do certainly do not eat the apples. Leave
this to the tortoises.
Speaker 2 (23:48):
Now, coming back to Darwin's writing on the tortoises, he
also observes their relationship with water. He says, they are notable,
of course for their ability to survive without water for
a very long time. But when they get out access
to water, they go hog wild. They love it, the
spring water and the mud puddles. They'll just get in
there and settle in, sometimes for days at a.
Speaker 4 (24:10):
Time, and when.
Speaker 2 (24:11):
They're drinking they will just gulp huge mouthfuls of water
for a long time. And Darwin even this leads into
him writing a really bizarre anecdote that I had to share.
So he says, quote for some time after a visit
to the springs, their urinary bladders are distended with fluid
which is said to gradually which is said to gradually
(24:32):
decrease in volume and to become less pure. The inhabitants,
when walking in the lower district and overcome with thirst,
often take advantage of this circumstance and drink the contents
of the bladder if full. In one tortoise I saw killed,
the fluid was quite limpid and had only a very
slightly bitter taste. The inhabitants, however, always first drink the
(24:54):
water in the pericardium, which is the membrane of belief
that surrounding the heart tissue, which described as being best.
So that's right, drinking the water from a tortoise's heart
or from a tortoise's bladder. And Darwin tasted the tortoise
bladder water.
Speaker 1 (25:10):
I guess I should be happy for this, that they're
using all parts of the tortoise conceivably in doing this.
But of course this is still kind of sad to imagine. Yeah,
but also from just a purely anatomical level, this is
of course amazing.
Speaker 2 (25:27):
Now, Darwin goes on to talk about how impressed he
is by the long determined journeys that some of these
tortoises make between He believes what the point of these
journeys is is between highland water sources and usual breeding
grounds in the lower districts. I don't know if that
holds up as the main reason for these journeys today,
(25:50):
though I do think some of these tortoises do make
journeys between the highlands and the lowlands for the purpose
of depositing eggs the females do after mating season. But
there are also journeys I think having to do with
food resources in the different seasons and so forth. But anyway,
Darwin says, you know, although the tortoises are pretty slow
in their movements, you would be surprised how much ground
(26:12):
they cover over time due to sheer determination. He estimates
that they're going to move sixty yards in ten minutes,
which is three hundred and sixty yards in an hour,
or about four miles a day.
Speaker 1 (26:23):
Yeah, it's pretty remarkable, and of course nowadays of course
that everything has been shifted around a bit. You know,
all these invasive species, not only the such harmful invasive
species as pigs and goats that were introduced and then
their populations have been dealt with to varying degrees. But
you also have, of course, have plants to think about,
(26:44):
and so in some cases you have things like berries
that are now grown in the Galapagos and may occur
wild in some cases, and of course the tortoises love
those even though they are not native, and so you
may see that interfere with their movements. So that but yeah,
basically through modern conservation and through modern tracking technology, you
(27:05):
can actually see all of these tortoise movements plotted out
on maps and it's quite impressive. I think they are
movements in these cases help illustrate why they're so crucial
for the island ecosystem that they thrive in. They eat
so much and while they're slow, they do cover a
lot of ground and defecate to spread speeds spread seeds rather,
(27:28):
and this is very much in line with other megafona
that you encounter in other ecosystems as well as the
remember if you think back to our episode on or
episodes on the giant moa bird, which of course is extinct,
but would have we still see like the footprint of
their ecological importance in the areas that they occupied, because
(27:49):
they were vital for consuming plants and then spreading those
seeds through defecation.
Speaker 2 (27:55):
Yeah, there is a great passage in the book by
Creature and Laughlin where they talk about the importance of
the tortoise in spreading a type a species of wild
Galapagos tomato plant, which apparently it only the seeds only
germinate under very specific conditions, such as being exposed to
acid for a long period of time.
Speaker 4 (28:17):
Now, how does that happen, Well.
Speaker 2 (28:18):
It happens in the digestive system of the tortoise. So
like they take this in, the seed gets exposed to
the acid within the digestive juices, and then it gets
it travels with the tortoise a long ways away from
its original location, so that's also good for dispersal. And
then once the tortoise poops it out, it of course
has a bunch of nutritious fecal matter surrounding it to
(28:41):
help it grow.
Speaker 1 (28:42):
Yeah, yeah, I've got I did get to poke some
tortoise dung with a stick. My son and I did,
and we got to look all in there. It's, you know,
quite fascinating. I think some stats would really help drive
home though, why the tortoise is so great at this.
And I got these from Seed Dispersal by Galapagos Tortoises
by Blake at All, published in the Journal of Biogeography
(29:05):
from twenty twelve. So, in this particular survey, the researchers
looked at one hundred and twenty fresh dung piles in
both agricultural and national parkland. They found seeds from more
than forty five plant species in these dung piles, eleven
of which were from introduced species, you know, like various
berries and whatnot. A per tortoise average of four hundred
(29:27):
and sixty four seeds and two point eight species per
dung pile was detected. Now, this is where it gets
kind of interesting, because, okay, we've already established that, yes,
they eat a lot, they travel farther than you might think,
But how long does it take for them to process
their food? Things go a little slower with the Galapagos tortoises.
(29:48):
The mean digesta retention time for a tortoise is twelve days,
but twenty eight day retention times have been reported, so
that's the time time it takes for the food that
they've consumed to process through their body and become dung, so.
Speaker 2 (30:05):
They can really cover some ground in that time.
Speaker 1 (30:07):
Yeah. During that time, according to this paper, the tortoise
may travel between three hundred and ninety four and four
three hundred and fifty five meters on the high end,
that's two point seven miles or four point three kilometers.
Speaker 2 (30:20):
So you can see how these tortoises would play an
incredibly important role in helping the reproduction and dispersal of
local flora.
Speaker 1 (30:28):
Yeah. Absolutely. I mean, as with any species, they don't
they're not existing in isolation in their ecosystem. They have
a roll, they have a place in it. And if
you disrupt them, if you disrupt their numbers, or in
the very worst case scenarios, if their extinction is brought about,
then there is there's something missing. There's a you end
(30:50):
up pulling the carpet out from everything, and unlike with
the parlor trick, all the plates and the dishes are
not necessarily going to stay standing up.
Speaker 2 (31:08):
Now we've been talking about a lot of the predation
and hunting of these tortoises. But barring that, how do
tortoises die?
Speaker 4 (31:17):
What happens?
Speaker 2 (31:18):
Well, Darwin writes, quote the young tortoises as soon as
they are hatched, fall preying great numbers to the carryon
feeding buzzard. I think that would actually be referring probably
to the Galapago's hawk, unless he's talking about some other
species that came in after humans arrived. But and Darwin
goes on, the old ones seemed to die generally from accidents,
(31:41):
as from falling down precipices. At least several of the
inhabitants told me that they never found one dead without
some evident cause, which, oh, that kind of gave me
a shiver.
Speaker 1 (31:53):
Yeah, yeah, I mean, it's just impressive how long they live.
That and I did the first point about P's worth
pointing out that the tortoise sanctuaries that are up and
running now they care for the little ones to protect
them from you know, not only the hawk, but also
all these introduced species that may be about once they
get big enough. Though, Yeah, there's only really three ways
(32:15):
they're going to die old age eventually, accident, vehicular especially
of course being the main threat, though on the Galapico
sidelands today a lot of you know, laws and messaging
have been put in place to prevent this from occurring.
And then of course in the past human hunting was
the big thing.
Speaker 2 (32:36):
Now you mentioned they can die of old age, of
course they do, but that can take.
Speaker 4 (32:39):
A good long while.
Speaker 2 (32:41):
I was reading about this in a Creature in Laughlin
and they say that it's possible, though we have no
way to know for sure, that there may be tortoises
still alive on the islands that were present when Darwin
visited in eighteen thirty five, and a Galopago's tortoise named
Harriet lived to an estimated age of one hundred and
seventy five before she died in an Australian zoo in
(33:04):
two thousand and six, so they can live a long
long time.
Speaker 1 (33:09):
Yeah, I was doing some crunching on this as well.
I think one of the sources I was looking at
had listed like one hundred and seventy one years as
being one of the oldest stage is known for the tortoises.
And even if you're just going to go with that,
if you consider the idea that you have a tortoise
born in eighteen thirty five when Darwin is visiting, if
(33:29):
it lived one hundred and seventy one years, it would
live to the year two thousand and six. Wow, which
is just crazy to think about the idea that just
one tortoise lifetime would bridge our time to the time
of Darwin, and that a single tortoise lifetime could encompass
basically the two worst centuries of the impact of humanity
(33:51):
on Galapago's tortoise numbers as well. Now, again not to
come back too much to the horrors of human tortoise interaction,
but yeah, there are these accounts read too of like
times when roads to various villages were just lined with
like the bones or the shells of these creatures. It
(34:11):
was it was a rough time to be a Galapagos tortoise.
Speaker 2 (34:14):
Yes, no, I now I think it's worth talking about
Galapagos tortoise mating and reproduction, which there's some interesting stuff.
For one thing I was reading about Maybe we can
get to the actual mating in a minute, But first
I was reading a section in Creature in Laughlin about
the nests and egg laying of the Glopagos tortoise. So
(34:38):
mating season typically occurs during the rainy season, and after
having mated, a female tortoise will generally travel toward the
arid lowlands to build a nest. Darwin has a section
about this where he correctly observes that they will seek
out arid sandy soil to dig a nest in, but
then he says others. He says, sometimes they will just
(34:58):
drop their eggs where like in a precipice, like in
a crevice in the rocks. I didn't find any other
evidence of that, so maybe that was true when he
was there, but I'm not aware of other evidence for
that other than what Darwin says. But generally what they
do is they're going to dig down in the arid regions. Now,
for the saddleback tortoises, which tend to live more in
(35:19):
the lowlands, this is not much of a trip. But
for the domed tortoises it can be a really great
journey down from the highlands into the place where they're going.
Speaker 4 (35:27):
To lay the eggs.
Speaker 2 (35:29):
And the eggs are laid sometime between June and December.
A clutch can contain anywhere from like two to twenty eggs.
The eggs are sort of billiard ball sized or maybe
a little bit larger. And the nest building process is
what interested me because apparently it involves a good bit
of pa. So the tortoise will find a spot in
(35:49):
the soil and she will dig a hole about thirty
centimeters deep, scooping the earth out with her hind legs,
and this is an involved process that can take up
to about twelve hours, and the tortoise will often urinate
on the soil in order to soften it for digging.
But the mother tortoise, after she lays her eggs in
the hole and covers it up, then also peas on
(36:11):
the soil again to form a kind of cement layer
in it.
Speaker 1 (36:15):
This is interesting. We've discussed a number of different nest
building egg laying scenarios over the years, but I don't
remember one that was so urine intensive.
Speaker 2 (36:25):
Yeah, there may be other species that do pie cement,
but this is the first time I remember reading about this.
So anyway, the eggs incubate in the cemented earth for
like four to eight months, where the sex of the
hatchling is ultimately determined by the temperature which the egg incubates.
That's kind of interesting. It's not chromosomally determined as it
(36:45):
is for some other animals, and so afterwards they dig
their way out of the nest to begin their lives,
and of course this is the most vulnerable time for
a Galapagos tortoise when they're a hatchling, but the ones
that survived make it out. They find food, they avoid predators,
and they eventually grow up, though apparently the growing up
also takes a good bit of time. The tortoises do
(37:07):
everything pretty slow, including reaching maturity. I've read that they
don't reach sexual maturity until several decades later.
Speaker 1 (37:15):
The mating itself is also kind of interesting because they
basically consists of the males chasing the females around until
they can corner them. But then there's also, given these
are large shelled creatures, the male's shell has like an
indention on the bottom that allows for it to mount
the female, because otherwise, unless there was some arrangement of
(37:39):
the shells in this capacity, that they would not be compatible.
Speaker 2 (37:42):
Right, And there was also a fact I came across
that I thought was funny. In this book, they talk
about how the larger size of the Glopagos tortoise can
make the physical active mating sometimes kind of cumbersome and laborious,
and the authors note that quote, males often slide off,
even inadvertently, landing upside down, at which point they must
(38:03):
right themselves and try again, which I don't know if
it's juvenile that I found that funny, but I did.
The authors also note that the male tortoises sometimes get confused.
For example, they try to mate with large rocks.
Speaker 1 (38:17):
Well, that's just, in and of itself funny. We can't
help but laugh at that.
Speaker 2 (38:21):
But there's also surprising. For these very slow moving animals,
there is some surprisingly fierce competition between males for access
to mates, and Darwin notes this. He says, during breeding season,
you can hear the males emit what he calls a
horse roar. And I think this roar is probably indicative
of male on male competition, which sometimes leads to these
(38:44):
mock fights where they will raise their necks up at
each other. Rob, I think you actually maybe saw one
of these going on.
Speaker 1 (38:51):
Yes, I got to see this happen, and I actually
got to film it. I was able to my wife
was like, quick, get your camera out, make sure you're
getting this. So I did. Yeah, it's amazing to watch
because you'll have these two lumbering giants that are kind
of on a collision course with each other, and you're like,
what's going to happen, what's going to happen? And then
as they get closer, they'll both rear their heads up
(39:14):
and they'll have this showdown that doesn't it does not
come to blows or bites or anything like that, but
it is a competition to see who to determine who
is the tallest and the tallest tortoise, who had the
one that can raise its head up the highest, he's
the winner, and the other one accepts defeat and carries on.
And that's as violent as it seems to get. But
(39:35):
it's spectacular to watch. And this was the finest nature
footage I have ever captured or will ever capture.
Speaker 2 (39:42):
Now, one last thing I wanted to read from Darwin
here where he's talking about the tortoise's reaction to humans.
This is another infamous section from the Voyage of the
Beagle chapter. Darwin says, I was always amused when overtaking
one of these great monsters as it was quietly pacing along,
to see how suddenly the instant I passed it would
draw in its head and legs and uttering a deep hiss,
(40:05):
fall to the ground with a heavy sound, as if
struck dead. I frequently got on their backs and then
giving a few wraps on the hinder part of the shells,
they would rise up and walk away, but I found
it very difficult to keep my balance.
Speaker 1 (40:20):
Oh, Charles, no doing, Why are you riding a tortoise?
I mean it is kind of I mean it based
on this account, the tortoise is doing exactly what you
know I observed, and all these sources say they do
if someone gets too close or something gets too close.
But it is kind of interesting this added detail that
(40:41):
apparently eventually the tortoise is like, Okay, I guess this
weird British man is not going away. I have things
to do in places to be I'm just going to
start walking around with him on there and maybe I
can sort of shake him off.
Speaker 2 (40:53):
Yeah, and this is actually not an isolated report. Again,
we are not recommending riding the tortoises, and other other
people talk about how well you can get on their
backs and ride them and they'll just go about their business.
And this is apparently a common occurrence. There was a
common occurrence.
Speaker 4 (41:09):
Back in the day.
Speaker 2 (41:10):
Sometimes they say, you can get two people on one
of these tortoise shells and just ride them and they'll
do their thing, like you know, they don't seem they
don't seem bothered. Now, I'm sure that puts extra strain
on their muscles and their energy requirements and all that.
So it's not like okay to do. But just showing
the strength of the tortoise and how powerful and huge
this animal is that it could just continue on its
(41:32):
way trying to graze with like multiple humans riding on
its back.
Speaker 1 (41:36):
Oh, poor creatures. Yeah, again, do not attempt to don't
do not get close to the tortoises, and do not
ride them. Now, we have a fair amount of variety
with the Glapygos tortoises that they're all of the genus Chellinitis,
and you get into some discussion about the different varieties
(41:57):
like the exact variety count. And then we have two
that are definitely extinct. There's the Floriana Island subspecies that's
thought to have been hunted to extinction by I think
eighteen fifty when Darwin visited. This is I believe the
one where he only describes seeing their bones. The Pina
(42:17):
Island species is extinct as of twenty twelve, with the
death of Lonesome George, who was of course famous for
being the last of his variety. He died and that
was seemingly it for this variety of tortoise.
Speaker 4 (42:31):
Yeah.
Speaker 2 (42:32):
I've read that there are either twelve or thirteen extant species.
Speaker 1 (42:38):
Yeah. So, coming back to the challenges that tortoises faced
during the age of humans, we've thoroughly discussed. I think
the human hunting and human harvesting of tortoises, at least
(42:59):
for our purpose, is here. But of course there are
all these invasive species that humans introduced, and while we
are dealing with cases in some cases where you'll have
animals directly going after young tortoises, there are also other
ways that these creatures were harmful and are and can
still be harmful to the native Galapagos tortoises.
Speaker 2 (43:23):
Right, And in fact, one example of this came up
in some episodes we did back in October on goats, right,
the issue of goats competing for resources with tortoises.
Speaker 1 (43:32):
That's right again. Goats, as we discussed, are amazing at
what they do at roaming around finding odd bits of
vegetation to consume, and yeah, they're they're ultimately better at
it than tortoises. They're more thorough than the tortoises, and
ultimately so thorough that they can be even more disruptive
to like the to the ground itself, like you know,
(43:56):
getting in there and actually making it unstable. So that's
that's one thing to consider. Also when you're dealing with
any creature that lays its eggs in the ground. Not
only do you have to worry with certain species, like
especially pigs and rats going after those eggs and then
going after the young. Potentially, you also have to deal
with cattle because there are still cattle on the islands,
(44:18):
and cattle were brought to the islands, and cattle aren't
interested in really eating those tortoise eggs, but they will
definitely step on those tortoise eggs if they happen to
be ranging in the same area.
Speaker 2 (44:28):
Now, in the previous episode, we talked about some hypotheses
about how marine iguanas first arrived on the Galapagos Islands,
probably via some kind of rafting from the mainland. Is
that also the idea of what likely happened with the
ancestral tortoises.
Speaker 1 (44:46):
That's my understanding based on the sources I was looking at,
and based on conversations with some of the naturalist and
guides in the Galapagos Islands. The idea is that it
would have been much the same tortoises in South America,
swept up in river floods, washed out with vegetation which
they were able to raft on, and reaching these far
(45:09):
flung islands.
Speaker 2 (45:10):
So it's amazing to imagine these extremely unlikely, kind of
one off events that allowed the population of each island,
because it's not something you see happening every day. But
you know, all it takes is a is a small
seed population to get there and then wow, what's this.
You know, there's all these food resources and no predators
and you can really boom once you arrive.
Speaker 1 (45:32):
Yeah. And I'm not sure if the numbers on this
are you know, certified as it were, but it seems
like the first Glapacos tortoises probably reached the islands two
to three million years ago via rafting. They would have
probably arrived on the eastern islands of Espanola and San
Cristobile first and then spread west from there. So it's yeah,
(45:57):
it's interesting to think about. Now. The other question that
I guess came up for me, and this was like,
how big were these tortoises when they first arrived, because
at least some sources out there make the case that
they were already big, that they were already quote unquote gigantic,
while plenty of other sources also discuss Glapago's tortoises as
(46:19):
a case of island gigantism.
Speaker 2 (46:21):
Yeah, so island gigantism is something that often occurs. There's
known as island dwarfism and island gigantism. These kind of
runaway pressures on the size of animals that can really
bulk them up or shrink them down when they're in
a contained ecosystem like an island. And I don't think
(46:42):
we know exactly what all the pressures would be, but
you could imagine something like, well, maybe there is always
sexual selection on, say the size of adult male tortoises,
to make them bigger and bigger, because the bigger you are,
the more likely a female is to be receptive to mating.
So there's a sexual selection driving them to be bigger.
But then there's naturally some kind of other pressure that
(47:03):
wants to keep their size smaller. You know, like you
there's that advantage in being bigger. But once you're bigger,
maybe you're more at risk of predation, or it's harder
to thermoregulate or something like that. And you can imagine
cases where you get on an island and suddenly those
other pressures are relieved and so you can just keep
getting bigger and bigger than you would have been allowed
(47:23):
to on the mainland.
Speaker 3 (47:25):
Yeah.
Speaker 1 (47:25):
Yeah, I guess on the like supporting the idea that
they were already big there is. There is, of course,
fossil evidence of gigantic tortoises existing on I think every
continent except Australia and Antarctica at some point in the past,
so it's not like these forms only emerged on various
(47:47):
islands island environments. But I don't know. On the other hand,
it seems like plenty of sources are discussing this as gigantism.
One paper I was looking at this is from Jaffe
at All, from a twenty eleven paper in the Royal
Society Biology Letters, The Evolution of Island gigantism and body
size variation in Tortoises and turtles. They point out that
(48:08):
they do point out that quote, the other evolutionary determinants
of size diversity in Chilonians are poorly understood. But they
also point out that Chelonians span some four orders of
magnitude in their sizes, and that there is quote a
pronounced relationship between habitat and optimal body size. Also worth
noting that the apparently the closest living relative to the
(48:30):
Galapagos tortoise is not a direct ancestor of those tortoises,
but it is itself a relatively small bodied variety of
tortoise that's found in South America, the Chaco tortoise, I
believe it is called now. I also mentioned that there
are other giant tortoises still in the world outside of
the Galapagos. These would be giant tortoises that survived in
(48:54):
the Western Indian Ocean in the form of Aldabra giant
tortoises leave.
Speaker 2 (49:00):
When Darwin arrived, he thought that these were the same species,
like that the ones on the Galapagos were the same
as those, or at least the same as some other
island gigantic tortoise he was aware of. I think it
would have been those, because those are the only other
ones I know of, and he was mistaken in that
in fact that they're just they're different parallel forms of
(49:21):
gigantic tortoises. But one last thing I wanted to talk
about with these tortoises before we wrap up today is
the differences in the shell shapes, because we mentioned earlier
that some species have more dome shaped shells and some
have these saddle shaped shells, and there are also intermediate
(49:42):
species that have sort of somewhere in between. A creature
and Laughlin have a great section on this in their
chapter on the tortoises, and I wanted to talk about
it a bit. So one of the questions is why
you can observe some things that might lead to these differences.
The tortoises with the domed shells tend to live more
(50:03):
in the highlands and around caldera rims, where vegetation is
much thicker and lush all the time, whereas the ones
with the saddle backed shells tend to live more or
even exclusively in the low lands, where conditions are more
often dry. Of course, the differences in these shells is
that while as the domed ones are more just kind
(50:24):
of like an upturned cup over the reptiles back. The
saddleback tortoises, their shell tends to have like a relief
area above the head and neck. It's almost like a
collar that's pulled back. And there are some other differences too.
The domed tortoises tend to have a larger body size,
but shorter legs and necks, whereas the saddleback tortoises tend
(50:47):
to be smaller overall but have longer legs and longer necks.
Speaker 4 (50:52):
Now, remember in the.
Speaker 2 (50:53):
Last episode when we talked about the marine iguanas and
we were trying to come up with the biological explanation
for why the iguana kept returning out of the water
after Darwin threw it in, even though you know it's
got to go in the water all the time to eat,
So why doesn't it just stay in the water to
stay away from him? And the answer we came up
(51:15):
with that the Darwin did not land on himself is
that it's probably for thermoregulation reasons because the water is
cold and it was removing heat from the iguana's body
and the iguana needs to get back up on land
to heat back up. I think a good explanation for
One of the explanations for the different body plans of
(51:37):
these different tortoises probably also has to do with reptile
thermoregulation with the regulation of body temperature, because of course,
animals with a larger body volume also tend to retain
more heat because they have less surface area proportional to
their volume. So if you're living in a cold place
(52:00):
and you're trying to retain body heat, it's easier to
do that if you're bigger. You've got there's just more
body in there and less relatively less surface area, and
vice versa. It's easier to cool off if you're smaller,
because a bigger percent of your body is surface area
that you can lose heat through. This would seem to
correlate with the observation that the domed tortoises, which live
(52:24):
up in the highlands where it tends to be a
little bit cooler, tend to have a larger body size
but also shorter legs and necks, so less extremities poking
out that can lose heat, whereas the saddleback tortoises tend
to be smaller overall, with longer legs and longer necks
and they live down in the lowlands where things tend
to be hotter.
Speaker 4 (52:45):
Yeah.
Speaker 1 (52:46):
Yeah, Now, most of the tortoises I got to observe
were definitely in highland environments, but their relationship with temperature
is notable as well. In one case, we've got to
go out and see these tortoises out there in this
this this this highland area, and it was early enough
(53:06):
in the day that some of them were essentially sleeping in.
They were still bedded down in the mud where they
could they could, you know, keep their temperature relatively stable
throughout the night. And some were already getting up to
begin their their day of eating. Others just weren't quite
ready yet.
Speaker 2 (53:22):
Oh yeah, And I've read that these tortoises just love
the mud, like they'll love to get in the mud
puddles and they'll just hang out there for days sometimes.
Speaker 1 (53:30):
Yeah, so you'll see them trooping around and yeah, on
one level, they kind of look like bulldozers because they're
just covered with mud, and of course they've been eating too.
There are lots of pictures you included one here of
one with just this spectacularly messy's face from all the
vegetation and or fruits it's been consumed. It's just smeared
all over.
Speaker 2 (53:48):
It's like one of those gross baby pictures where the
baby just looks they've been face down in a play
of spaghetti.
Speaker 1 (53:54):
Yeah, and their face, the face of the Glabgos tortoise
does kind of look like like old baby, so it
really matches up with that well.
Speaker 2 (54:03):
But there are other differences in the environments that might
explain the different body plans of these tortoise species, So
a lot of it probably has to do with vegetation.
Speaker 4 (54:14):
Right.
Speaker 2 (54:15):
Domed tortoises tend to live in more lush highlands with
dense undergrowth and a creature in Laughlin right quote. The
domed shells, smoothly rounded as they are, may prove adaptive.
Is the tortoises move tank like through dense plant cover,
which is of course also the animal's food source. On
(54:35):
the other hand, saddle type shells with a large forward
notch can actually become snagged in low vegetation, impeding the
movement of the tortoise. Saddle shells are not very adaptive
in low dense vegetation, so it's just going to be
easier to move around with a more rounded shell. In
all that thick brush in the Upper Highland forest regions,
(54:57):
whereas if you had the saddle shell with the turned
sort of collar in the front, Yeah, they'd just be
getting hooked on stuff all the time.
Speaker 1 (55:04):
And I mean they are little bulldozers. They can tear
stuff up. Like for instance, you know there are gonna
be limits. They could continue, you know, be slowed down
or I guess stuck in vegetation. But to give one
example that I was told about, do you have again
individuals who are still ranching in these in these parts
of the Highland, they have cows. They need to contain
(55:26):
those cows. But if they're gonna be tortoises moving through,
they're gonna they're just gonna take down your barbed wire
fence or your your whatever kind of fencing you have.
So in many cases they'll have the fencing, they'll have
this big gap at the bottom that will allow a
tortoise to move through, because that way you still get
to have your fence and the tortoise won't won't tear
it down when it makes a bee line for whatever
(55:48):
wherever it's going.
Speaker 2 (55:49):
Yeah, fortunately the cows can't crawl under Yeah.
Speaker 1 (55:52):
I guess not. It did raise some questions like, well, yeah,
can the cow what about really short cows? I don't know,
but apparently it works.
Speaker 2 (56:01):
But the final thing with the difference between the domed
tortoises and the saddlebacks is probably food sources as well,
because again, the domed ones are going to be munching
on a lot of you know, lush, low lying vegetation,
so you know, that's just that's okay to have a
normal kind of dome dome shaped shell for that. But
(56:23):
the saddleback tortoises, which live in the more arid lowlands,
are going to be eating cacti, often tall cacti that
they need to reach up to get to, and so
the upturned front of the shell allows more room to
raise the neck, and of course, of course, as I
said as well, they've got longer necks and longer legs
to help reach Robin, I think you said you observe
(56:46):
stuff about those cactuses sort of reacting to that by
growing taller and taller to try to escape the munching tortoises.
Speaker 1 (56:54):
Yeah. Yeah, And it's it's remarkable to see because yeah,
here's this, here's this cac that has evolved to thrive
alongside the tortoises, and it ends up, Yeah, it ends
up feeling more like a tree than a cactus, if
that makes sense. Yeah, it's a remarkable ecosystem.
Speaker 4 (57:12):
All right.
Speaker 1 (57:12):
So there you have it. Hopefully we gave just at
least a nice snapshot, a nice overview of the Galapagos tortoise. Obviously,
there's a lot of research out there about these creatures,
so perhaps there's some details that we managed to leave out.
If you think that we left out something that is
particularly exciting, then right in. We'd love to hear about it.
(57:33):
We'd love to see it for ourselves and to share
it in a future listener mail. Likewise, as I mentioned
the first one, if you've traveled with the Glabgos Islands,
if you live on the Galapagos Islands or are an Ecuadorian,
we would also love to hear from you. We love
your thoughts on these fabulous creatures that we've discussed here,
or any of the other creatures of the Glabgos Islence,
(57:54):
I'm always excited to hear more. Just a reminder to
everybody's Stuff to blow your mind. Publishes us it's core
episodes on Tuesdays and Thursdays. In the Stuff to Blow
Your Mind podcast feed we have listener mail episodes on Mondays,
a short form artifact or monster fact episode on Wednesdays,
and on Fridays we set aside most serious concerns and
just talk about a weird film.
Speaker 2 (58:15):
Huge thanks to our audio producer, Max Williams. If you
would like to get in touch with this with this podcast,
with us with feedback in response to this episode or
any other, with a suggestion for a future episode topic,
or just to say hello, you can email us at
contact at stuff to Blow your Mind dot com.
Speaker 3 (58:43):
Stuff to Blow Your Mind is production of iHeartRadio. For
more podcasts from my Heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you're listening to your favorite shows.
Plates rat late ratt
Stuff To Blow Your Mind News
Hosts And Creators
Robert Lamb
Joe McCormick
Popular Podcasts
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com
24/7 News: The Latest
The latest news in 4 minutes updated every hour, every day.
Therapy Gecko
An unlicensed lizard psychologist travels the universe talking to strangers about absolutely nothing. TO CALL THE GECKO: follow me on https://www.twitch.tv/lyleforever to get a notification for when I am taking calls. I am usually live Mondays, Wednesdays, and Fridays but lately a lot of other times too. I am a gecko.