December 25, 2018 • 47 mins
Welcome to Christmas Island, a place where it’s still only Christmas once a year… but where red crabs swarm across the land and enormous coconut crabs feast on carrion in the forests. So deck the halls with boughs of SCUTTLING HORROR as Robert Lamb and Joe McCormick celebrate the holiday season in style.
Learn more about your ad-choices at https://www.iheartpodcastnetwork.com
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 (00:03):
Towards the Island of Christmas, and all across the land
the red crabs were flowing across root Street and sand
like a red tide of scuttling, claw snapping doom. They
streamed through my front door and into my rooms. Meanwhile,
in the forests the giants, they're crawled coconut crabs, hulking
monsters with claws. They hunted for carrion crab bird and
(00:26):
ratted and gobbled it up, rancid, sinew and fat. Welcome
to Stuff to Blow your Mind from how Stuff Works
dot Com. Hey, welcome to Stuff to Blow your Mind.
(00:46):
My name is Robert Lamb, and I'm Joe McCormick, and
getting in that holiday spirit. We're gonna be talking about
crab Horror. Yes, this is this pair of episodes. I've
been looking forward to all year. This has been my
my goal. I forget when, but earlier in the year
I was reading about Christmas Island and and the various
creatures that that call it home, and I realized, we
(01:09):
have to do this episode for Christmas, even though this
really has nothing to do with Christmas, no, virtually nothing
to do with Christmas, though I do enjoy um like
forcing decapods upon Christmas and uh and and and at
least in my mind, allowing them to take over the
holiday decapods with bows of all? Is it bows? I
(01:30):
should have said clause of glory? Either way, I appreciate
the holiday zeal. Now, so we're going to be going
to crab Horror Island, and there are many wonderful movies
and maybe we'll save it for next time to talk
about our favorite Crab Island movies. But the giant crab
is one of my favorite kind of movie monsters, and
they've always got to have their own island of terror,
(01:52):
right right, and and so in discussing Christmas Island and
these two episodes, we're going to talk about crabs or
you know, decapods anyway that are either enormous, uh, singularly
and enormous or collectively enormous. I think the first episode
we're going to focus on the collectively enormous, and the
second episode will focus on the decapods who are individually enormous. Now,
(02:15):
this first episode is going to focus on the Christmas
Island Red crab. Robert, will you take me on a
mystical adventure to crab Horror Island? Yes, we're talking about
Christmas Island, so named. It's in the Indian Ocean, about
three hundred and fifty kilometers or two hundred and twenty
miles south of Java and Sumatra and around uh, let's
(02:36):
see one thou fifty kilometers or nine hundred and sixty
miles northwest of the closest point on the Australian mainland.
Technically part of Australia though right it is an Australian
external territory. It has an area of a hundred five
square kilometers or fifty two square miles, so not huge, No,
not a big place at all. It's a very old,
(02:56):
though very old volcanic seamount island. It was first visited
by Europeans in sixty three Captain William Minors of the
Royal Mary and English East India Company vessel. He just
named the island when he sailed past it on Christmas
Day of that year. That's that's the only Christmas high
end there he didn't find, you know, and naturally occurring
(03:19):
Christmas tree there. Uh, there's no wasn't where the elf
workshop was exactly. There's there's nothing else about it except
it was Christmas Day when he found it. It could
have easily it could have easily turned out to be
Christmas Eve Island or Boxing Day Island or Halloween Island.
That would perhaps be a little more appropriate. Yeah. Uh So.
(03:39):
One of the cool things about this place is that
when when they were able to take a closer look
at it, they realized that it was uninhabited, at least
by humans. So it's obvious that what makes this island
unique is not anything about the indigenous culture or anything,
since it was apparently uninhabited originally, but it was not
uninhabited by wildlife. Fest we've made clear the wildlife there
(04:02):
was of a terrific scuttling variety, oh correct. And one
of the really cool things about the scuttling life on
Christmas Island it is that so much of it is
on Christmas Island. We're talking about land crabs, crabs that
need only returned to the water to mate, but mostly
live on land. And you'll find these elsewhere. To be sure,
this is not the only place land crabs can be found.
(04:23):
Uh And we're we're talking about both true crabs as
well as hermit crabs here. Hermit crabs are decapods, but
not true crabs. But forgive us as we as we
talk about them in these episodes, I will probably end
up calling them both crabs in the unofficial sense. The
Christmas Island is home to more land crabs than anywhere
else on Earth. We're talking more than twenty terrestrial and
(04:46):
semi terrestrial crabs species, plus a hundred and sixties species
or thereabouts in the reefs and shallows around the island. Yeah,
so Robert tell me a little bit about crabs. Well,
just to refresh everybody, crabs are crustaceans. But we should
be clear that again, there are true crabs of the
decapoda soap order bracci ura, which means small tail um,
(05:07):
which references their smaller abdomen. And then there are the
ano mora or mixed tail crabs, which included hermits and
as we'll discuss later in the second episode, robber crabs.
But still again we're often going to refer to them
both as crabs in the unofficial sense. And these were
these are ancient creatures. These were the first animals to
(05:27):
develop true legs, none of those false legs. Yeah, I mean,
we we've talked about crabs on the show before. I
think back to our episode about Carl Sagan and the
Samurai Crabs. So so hopefully everyone is is on board
for two more episodes of of crab based content. But
so it's not just the varieties of crab and crab
(05:49):
like creatures that live on Christmas Island that make it
crab Island Earth, Uh, it is is the number of
a particular species of crab there, the Christmas Silelan red crab,
where there are supposedly tens of millions of these crabs
on the island. And this is not a big island. Remember,
it's a hundred thirty five square kilometers, right, a small island.
(06:12):
And yet yeah, I've seen the figures of like fifty
million of these creatures living, living in the forest, living,
you know, pretty much all over the island. And that's
a reduced number. I remember we watched a documentary about
the island from the nineteen eighties that suggested, at the
time it was believed that there were over a hundred
million of the crabs. They're right. That was a night
David Attenborough narrated special titled Kingdom of the Crab, great title,
(06:37):
and that's a great one to watch if you get
a chance, because it really shows off what makes this
island visually astounding, but it's the sheer numbers of the
crabs and the Christmas Island red crab is pretty much
found only on Christmas Island. Yeah, I think maybe on
another nearby island or island group, but they're not found
like all over the place. So I do want to
(06:58):
come back to the human history for a little bit
where we we explore the red uh crab in depth.
So the most you know, essential thing about human history
of Christmas Island is that for the longest there seems
to have been none. It is a geographically isolated place
now from everything I've read so far, and it's always
possible on missing something, but there's no evidence that humans
(07:20):
ever visited the place before the seventeenth century. See this.
Despite Java being again only two miles away, it's a
short enough distance for modern humans anyway that boats of
asylum seekers frequently make it their point of destination in
reaching Australia, because again it's an Australian external territory, So
if you reach Christmas Island, you are, you know, in
(07:41):
a legal sense, in Australia. However, it's also worth pointing
out that the seas can be deadly uh, surrounding Christmas Island,
and there are stories out there boats of asylum seekers
breaking on the rocky coast with lethal results. I think
I've read about this in cases of the early visitors
to the island. Also that you know, it was kind
of dangerous to land there. And for example, there was
(08:03):
one case where I read that a crew was driven
to land there because there was scurvy on the ship
and it was only because the disease had gotten so
bad that they risked trying to land. Yeah, that's sort
of the typical story book reasons for landing on an
uninhabited island with a strange crab population. Yeah, but out
of the scurvy pan into the crabs. Yeah, and you
(08:23):
know it, but but it is. It is weird to
think about places like this, places where where humans just
didn't take up residents. And of course you have to,
of course realize that moving to an isolated island is
a difficult proposition, like you've really got to have a
reason to go there and a reason to stay there,
and a way to um to to safely arrived there
(08:45):
as well. But still, you know, it's enough to make
one wonder. For instance, Homo Erectus or a Java Man
lived on the island of Java, relatively close by one
point seven million years ago. Humans practiced agriculture there on
Java as early as b C. Java was known to
traders and other powers. The Kingdom of Mataram ruled there
(09:08):
until they lost power to the Dutch East India Company
in seventy nine and became a vassal state of the
company UM, a statement that I think really drives home
the power of the East India Company UM, the idea
that you would have a vassal state to a corporation.
But that's a job. My point is that I just
(09:28):
find it so enthralling that this island remained either free
of human contact for so long or only encountered minimal influence.
You know. It's I guess it's possible that it's at
some point somebody wound up there by purpose or accident
and didn't didn't stay long enough to leave a footprint,
you know. Galapagos Islands or another example of this, though
(09:48):
there there have been at least disputed claims of Inca
artifacts found on the Galapacos Islands, perhaps due to Inca
sailors being blown off course. The statials in the Indian
Ocean and are another example of islands that were uninhabited
through most of recorded history, though they may have been
visited by early seafares as well, depending on who you
talked to. But with Christmas Island, I found no such thing,
(10:10):
and not even a crackpot theory. So it really does
seem as if humans, not even the Vikings, went their
theory by no Vikings or anything. So it really does
seem that nobody visited it until the seventeenth century, with
the earliest sighting I think having occurred in sixteen fifteen.
Now after that, of course, it actually did become an
economically significant island because of mineral deposits discovered there. That's right.
(10:34):
It was explored by British naturalist John Murray, and this
was eighteen seventy two. He discovered that there were phosphate
deposits on the island, which would play a key role
in the island's future. Exportation of phosphate begin in eighteen
by the Christmas Island Phosphate Company, and this activity led
to the loss of twenty of the island's rainforest area. Yeah, Now,
(10:58):
phosphate was important in the late eight hundreds because it
had been discovered by that time that phosphate, when treated
with sulfuric acid, could be used as an ingredient in
plant food, and of course synthetic fertilizers became very important
in the development of commercial agriculture at scale, and so
now there was a reason and economic reason for people
to not only go to Christmas Island but to work there,
(11:22):
and so settlement began in the eighteen eighties. Uh later on,
during the Second World War there was a Japanese occupation
of the island from ninety five, and in the post
war period it was administered by Singapore, which was then
a British colony, and then Australia purchased the island for
two point nine million pounds on January one, nineteen fifty
(11:43):
eight day that's known as Territory Day on Christmas Island.
Today it has around I've read two thousand full time
human residents and the ethnic makeup is mostly Chinese in
meleay Um originally brought in for labor. Now a big
poor scan of the land of the island today is
basically a national park. It's like a big wildlife preservation area. Yeah,
(12:08):
two thirds of its land mass are national park. Now,
and a big part of the wildlife significance here is
the Christmas Island red crabs. So I guess we should
dive headfirst into a puddle of crabs after we come
back from a break. Alright, we're back, so it is
time to dive into a pit of crabs. The Christmas
Island red crab or get Karcodia natalis. And these are
(12:32):
crabs that live, as we mentioned earlier, primarily not in
the ocean, not even on the shoreline, but in inland forests.
So if you picture Christmas Island, it's sort of a
terraced rainforest. It's a you know, volcanic island. It's got
some steep slopes that go up onto rainforest covered terraces,
and the crabs go all the way up into the
(12:53):
forests and make their burrows inland. Yeah, we're talking against
something like fifty million of these a little land well
ers uh in the forest chewing up leaf litter. And
here on Christmas Island they are the chief decay agents
for that leaf litter. I've seen estimates of something like
four thousand crabs per acre to keep the leaf litter down. Yes,
(13:14):
and they primarily feed on plant matter like you say,
so that is going to be leaf litter. It's also
things like fallen fruits and seeds, flowers, et cetera. But
they're also crabs after all, so you might not be
surprised to learn that they are opportunistic omnivores. My favorite
pairs of words. So if you get a little bit
(13:34):
of meat from say another dead red crab or something
like that presenting itself, this is a legitimate score, and
they will say, gentlemen, get that in my mouth parts.
It's time to masticate. But the crabs are important for
the maintenance of the ecosystem in multiple ways. So they
clear the forest floor of like leaf litter, but also
saplings and flowers other plants that would create dense underbrush,
(13:58):
and so they keep the forest floors lean, and this
actually helps contribute to forest biodiversity. They also prevent the
soil from being packed too densely because of the burrows
they dig. They're like natural soil tillers. They turn the soil,
and this also helps contribute to forest biodiversity. But so
we might have a pretty good sense of what the
(14:19):
life of an ocean dwelling crab is like. What is
the life of a land crab like crabs, as you
can imagine, in between chewing up things in their environment
and eating it, they have to stay moist and this means,
for one thing, staying out of the direct sun. So
the red crabs on Christmas Island like to stay in
the shady forests and they live in these dugout burrows
that they can hide from the sun in and they
(14:41):
have guilt chambers that have adapted for terrestrial life. They
have to keep them moist, and they also I love this,
they have to manually wet their eye stalks. Yes, I
love this. It's pretty cool to watch if you can
find video of this. So their eyes talks emerge from
little cups in their carapace, and they don't have eyelids
of course, and by the way, just try to imagine
life without eyelids. Kind of a terror. So they wet
(15:05):
and wash their eyes by filling their eye cups up
with drops of water and then dipping their eyestalks down
into the cups to rinse them off. Yeah. I think
this is This is one of the great things about
watching any crab close up, but especially with the Christmas
crabs is those tiny little sort of methodical movements that
(15:25):
you see take place with their mouth parts and their
their eyes stalks totally. Now, despite their life in the woods,
they still have to return to the sea to spawn,
and this results in a vast scuttling migration that is
truly unlike anything else on earth. This is why you
will you will see. You know, there's so many different
documentaries about Christmas Island. That's why there's so much great
(15:47):
footage because they they go on these enormous migrations and
we're talking a several kilometer journey each year. Yeah, this
is crab Apocalypse. This is where the real show is
on Christmas Eye. And so around the beginning of the
rainy season, which is sometime October through December, the red
crabs begin this migration for their breeding cycle. And the
(16:10):
migration begins with the males, usually the biggest males, who
will crawl out over land from their forest burrows to
the shore where they're going to eventually get there and
dig new burrows for mating. And as the males make
this journey, the females eventually joined them in the journey
and they march towards the sea. Now, once the crabs
(16:30):
reached the shore, but before they dig their burrows to mate, uh,
they typically wash themselves off in seawater, though strangely enough,
they have to be careful not to get fully sucked
out into the sea because these are land dwelling crabs.
This is how they've evolved, and they can neither breathe underwater,
nor can they swim very well. These are crabs who
(16:50):
are not very good at being crabs. Yeah, so the
truly aquatic crabs in the neighborhood are just probably watching
this in halfing at them. But there's so many of them.
How could you laugh at them? Because they could really
gang up on you if they got a hold of
your right But so they would rinse themselves off in
the sea water. And then the males dig the burrows. Now,
(17:11):
sometimes when they dig the burrows, usually they'll go up
a little bit from the beach and one of the
forested areas just right by the beach, and they'll dig
these burrows. And sometimes the males have to defend their
burrows from other males, who of course think, hey, why
dig one when you can just claim somebody else's. So
there are sometimes these fights and dominance displays, a lot
of claw waving to keep the burrows secure, and then
(17:34):
of course the females come in and they will find
a male with a burrow and initiate the mating. And
by the way, if you've never watched crabs mating before,
it's one of the funnier looking types of animal sex.
I think it's just crabs look funny no matter what
they're doing. But also if you can just watch their
eyes while they're mating, it's really something special. It's you know,
(17:58):
it's like two googly eyed robots trying to be sexy
at each other and then throwing some claws and swiveling
mouth parts. It's just awesome. Now you mentioned the waving
of the clause, I want to I was reading a
little bit about crab clause in Douglas j Imland's book
Animal Weapons. Uh and he goes. He spends a little
bit of time talking about, you know, how these are
high energy adaptations packed with powerful muscles. They need to
(18:19):
be able to break through the exo skeletons of of
rival males in many cases. Uh And he mostly looks
at fiddler crabs in this book. But but, but it's
interesting stuff. The economics of not only having growing, evolving
gigantic class, but waving them around, because that's that's part
of having the cleaving clause or a claw, is to
(18:39):
wave that sucker around, yeah, or like flexing your muscles,
like showing off the guns. Yeah, you have to show
off the guns. That's that's part of having them, right. Yeah.
So the female will generally find a male and a
male with the borrow and they will mate, and then
after mating, what the males do is they just pack
up and headback inland. Their work is done, and they
(19:01):
leave the females by themselves in the seaside burrows. And
there's another interesting thing about this. Okay, so the red
crabs are sort of moon worshiping druids. The breeding migration
has to be timed exactly according to the cycle of
the moon because the cycle of the moon affects the tides.
So the adult crabs arrive at the shore and then
(19:23):
they mate, and after mating, the females produce eggs within
about three days, and then they remain in their burrows
for another twelve or thirteen days. And after this they
emerge from the hole in the ground and they release
their eggs into the sea water. And it has to
be timed exactly at the turn of high tide as
the moon goes from its last quarter to a new moon.
(19:45):
And this is because it's when the tide conditions are
just right to be releasing uh the young. But if
the migration is delayed by weather so that breeding can't
be timed exactly right with the phases of the moon,
the crabs will just wait. They'll just wait until the
next month to breed because it's not it's not going
the moon isn't right. So when the time is right,
the females release their eggs acts, which looks kind of
(20:07):
like a weird foamy sponge that they carry on the
underside of their bodies. They release these eggs acts into
the water. Yet again, I can't help but notice that
my wonder at these animals is combined with hilarity on
seeing this, because in some cases, the female crabs have
to release their eggs into like rough surf while clinging
to rocks above the water, and they're trying to be
(20:29):
careful not to fall in. And when you see footage
of this, the way they're just frantically shaking their bodies
to knock the eggs acts off, dumping thousands of eggs
off a cliff. I can't help but laugh. It's funny.
And then also sometimes they'll they'll go into the surf
on a beach and you'll see them like raising their
claws and shaking their bodies, like get off, just dumping
(20:52):
all these eggs off into the water. I don't know,
it's it's funny to me. Well, by human comparisons, they're
maybe not great moms, but by but by Christmas Island
Red Crab standards, moms of the Year. Yeah, exactly, and
that this does make me think about the ways that
we anthropomorphize good parenting. I want to come back to
that in just a minute. So the eggs are released
(21:12):
into the surf and they hatch pretty much immediately, and
then you've got these hatchling crab larvae that live in
the water for about a month, transforming through large larval stages,
and then they returned the shore in this seething foam
of what looks like pink ants. This is also just
astonishing to see, like the original migration from the forest
(21:33):
to the shore with the beaches and rocks covered in
this surging pink shag carpet of tiny millimeter sized baby crabs.
And then they molt, and immediately after molting, they they
are committed to an air breathing life on land, and
they travel inland to do as their ancestors did before them.
And this growth from about a five millimeter baby crab
(21:55):
stage to adulthood usually takes about four years, during which
time they mostly tend to hide out undercover until they
get big enough to fend for themselves. But yeah, back
to this idea about the way we look at non
human animals and tend to to judge their parenting. I mean,
that's inherently what I was doing when I think it's
funny just watching the mother crabs chuck their eggs off
(22:17):
a cliff. But it's like it's hilarious watching a crab
vigorously shake its body to knock all the eggs off
and stuff. But it's because we've so deeply internalized the
brood protection tendencies of mammals. Mammals tend to keep their
offspring close and take care of them for for like
extended periods of time while they mature, and that would
(22:38):
make no sense for crabs to do. First of all,
of course, it is just mechanically the case, because the
eggs need to hatch in the water. That's what chemically
and mechanically they do, but also mathematically, the parents have
a totally different relationship with their offspring. Mammals tend to produce,
you know, relatively small numbers of offspring and invest a
lot of energy into caring for and protecting them. But
(23:01):
I was trying to do a little bit of rough
math about the red crabs. So let's assume there are
fifty million adult red crabs on the island, and then
you've got mated pairs, and each mated pair of adult
crabs produces tens of thousands of eggs. I've seen a
common figure of a hundred thousand eggs per female crab sited.
So if fifty million crabs made it and produced twenty
(23:23):
five million eggs sponges, and each of those had a
hundred thousand eggs in it, and all those eggs survived
to adulthood, that would be two trillion, five hundred billion crabs. Now,
Christmas Island is about a hundred and thirty five square kilometers.
If my math is right, this means that just after
one year there would be a Christmas Island would have
(23:44):
eighteen point five billion crabs per square kilometer. So you're saying,
as a red crab mom, you have to be willing
to let some of those crabs go because you have
you have the numbers on your side, right. I mean,
it's just a totally different way of of have a
relationship between generations, right. They're going for for numbers. You know,
it's quantity rather than quality. And it's just impossible for
(24:07):
all those young to sustainably survive. Even if a decent
fraction of them survived, it would be ridiculous. Only a
tiny fraction of them can possibly make it to adulthood
in any ecologically sustainable way. And so most that get
dumped out into the water to hatch never make it
back to shore alive. They get washed out to sea,
never to return. Apparently, whale sharks migrate to the Christmas
(24:30):
Island area to eat red crab larvae when they hatch,
and among those that do make it back to the
beach in that in that you know foamy pink shag
carpet I mentioned, they're obviously going to be pretty easy
prey at that stage too. You can even sometimes see
I've seen footage of this of adult red crabs just
kind of shoveling clawfulls of young red crabs into their mouths,
(24:51):
because hey, what are the chances that these are mine?
It's pretty slim. Again, it's a numbers game. Well. Plus,
it's like they're just against so many of them. It's
like if you make way too much a pancake batter, Uh,
you may treat yourself to a few spoonfuls of unclid
pancake batter. I mean, why not, it's there. You can
only make so many pancakes. You can make similar argument.
You'd be like, look, if I made all of this
(25:13):
into pancakes, our house would be packed with pancakes six
ft high exactly. But anyway, given this kind of life cycle,
in these kind of odds, the way to be a
good parent is to do exactly what the female crabs do.
They shake them off into the water where they've got
a chance, and then they call it a day. There's
nothing more you can do at that point. And if
somehow you were still around when they hatched and molted,
(25:35):
who knows, you might just gobble them up. So, despite
how funny it looks, I rebuke my instincts. I do
not think that the red crabs are bad parents. I
think they're awesome crab parents. All right, we're gonna take
a quick break, and when we come back, we're going
to get into the human element. What happens when we
have the human element to the red crab element. Thank alright,
(25:55):
we're back now. We discussed earlier how crazy these migrations are.
You when the island can, sometimes in areas, become just
thick with crabs that are moving from forest to shore
or returning from shore to forest. And this doesn't even
take into consideration the fact that sometimes there are multiple
waves of migration during the same year. So you've got
(26:17):
crabs going both ways. Like one set of crabs they
moved down to the shore, and then there's another, uh
you know, trigger of the rainy season, another set of
crabs they start moving to the shore, and then the
other ones are going home. So you can have crabs
going this way, crabs going that way. There on the
golf course, there on the streets, there in the grocery store.
I mean, it can become quite thick with crabs on
(26:39):
Christmas Island. And yet there are people here, that's right,
and those people have vehicles that they also have pets. Uh,
we'll get into some of those complications in a bit,
but just the roads. You're talking about something like a
million crabs a year crushed by road traffic on Christmas Island,
but that's still only gonna shake out to something like
one percent of the population. And the dead, by the way,
(27:02):
are apparently swiftly cannibalized. Again, crabs. Crabs are gonna do
what crabs are gonna do. No. I mentioned earlier that
there's this great old British TV documentary called Kingdom of
the Crabs and narrated by David Attenborough from nineteen I think, yeah,
that was the same year that we got John Carpenters
They Live, Killer Clowns from Outer Space, The Blob the remake,
(27:24):
the really cool eighties remake, as well as of course
Mac and Me. Well, this is right up there with those.
But it's got so many great moments. And one of
the best moments from it is when you're watching hundreds
of crabs scuttling across a pair of railroad tracks and
then a train emerges in the background and it's barreling
towards the crab crossing, and then the crabs show no
(27:45):
sign of getting out of the way, and then the
train conductor starts blowing his horn at the crabs as
if that's going to deter them. I guess it's like
when people like they stop in the road because the
turtle is crossing and they honked their horn at it.
I never actually haunt my hornets, they squirrels, chipmunks, but
I will almost wreck my vehicle to avoid them. But
(28:07):
I I guess that's human nature. Like you don't want
to squish crabs unnecessarily. I mean maybe some people do.
There are probably a few people on the island who
kind of get off on it. Well, I've read that
it can. It can also hurt your tires. Yeah, you
have people with flat tires due to the crabs. Probably
hurts trains less, probably, Uh. But the humans have had
(28:28):
to put in place many steps to help the crabs
cope with roads and tracks and the other ways that
we have unfortunately disrupted their migration zones. I mean, it's
not the crabs fault, right, They didn't ask us to
put a road there, but railroad tracks there to do
all that kind of stuff. So these adaptations are are
pretty interesting. They include barriers of course around the edges
(28:50):
of roads and put walls around the roads to keep
the crabs from walking onto the roads, and these lead
to sort of crab funnels that route the crabs to
specially designs safe crossings, so you might have an underpass
with a great on top of it, or even there's
even a five meter high crab bridge climbable by crab
to help them over one stretch of road. Oh yeah,
(29:12):
and you included a picture of these in our notes.
It's pretty incredible because it looks like one of the
recognizers those enemy ships in the Tron movies. Yeah, it
looks like like that the big clamp that comes down
on top of you, right, except instead of being made
out of brightly colored light, it's covered in brightly colored
red crabs right now. Interestingly enough, early accounts of Christmas
(29:35):
Island make no real mention of the crab hoardz. So
you could you can look at that one of two ways, right, Well,
either it didn't occur in this at least with the
same at the same level, or they just forgot to
mention it, which seems unlikely, but maybe they didn't witness it. Well,
it's true too, but there is this suspected link between
(29:57):
the current levels and the decent levels of of of
the red crab population with the extinction of two species
of rat that were on the island when Europeans first arrived.
And uh, and it's possible that these two species of
rat may have kept the populations more in check. What
(30:18):
are these rats alright? One is called mcclear's rat or
memor Rattis McCleary and the other is the bulldog rat
or Rattus nativitatis. And those are just two of only
five native mammal species on Christmas Island to have been
officially listed as extinct since human showed up. That being
(30:39):
both of these rats, and the reason that they went extinct,
it's it's probably because exotic rodents were brought in by
early human colonizers or brought in. I would say they
just came along with let rats do. Okay, So the
ideas that humans brought different kinds of rodents, those rodents
out competed the native rodents, but those rodents weren't as
(31:00):
much of a competition with the red crabs. Well, it's
more than just outcompete as apparently like straight up killed
them off with illness. It was looking at a two
thousand eight study published in PLS one, and they pointed
out that there seems to be a direct cause here
and it seems to be disease. They collected DNA samples
from the islands now extinct native rats via late nineteenth
(31:23):
and early twentieth century museum specimens, and they attributed the
extinction event here to ship jumping black rats infected with
the protozoan Tripenasoma louizy, an organism that is related to
an organism that causes sleeping sickness in humans. And indeed,
native Island rats were seen to stagger around following the
(31:46):
arrival of the s S Hindustan in eight and this
protozoan is light is likely spread by fleas, so we
have you know, it's a similar situation that we've seen
with certainly with with human populations and UH and other organisms,
where an exotic variant brought in a parasite that the
UH that the native inhabitants were just simply unable to
(32:08):
deal with. Now, in terms of other native Christmas Island mammals,
others have had a tough time as well. The Christmas
Island shrew is critically endangered. There's also a particular bat
the Christmas Island PIPISTRELLI, Yes, thank you for helping that one. Now,
(32:30):
it's it's name. It is a cute name, a cute
name for a bat. It's critically endangered, if not outright extinct,
and apparently the reasoning behind that is is not completely understood.
There's also the Christmas Island flying fox, which is another
type of bat. It is also in decline for unknown reasons.
And then you have the exotic mammals. We've already mentioned
(32:51):
black rats, but you also have a house mice, you
have feral cats and wild dogs. Now do we know
what the explicit relationship between that change in the mammal
populations and the surge and crabs is. The belief is
that those populated the original populations of rodents were helping
to keep the population of crabs in check, and apparently
(33:13):
the the the exotic mammals have not been able to
keep their numbers in check the same in the same rate.
I see, So they're not adapted to to crab Island, right, Yeah,
it's it's one of those situations where again you just
see humans show up in the unbalanced things. Now, in
the case of the red crabs, it would almost seem
like the unbalancing made more spectacle right, Like the reason
(33:36):
we're talking about Christmas Island is because we have this
enormous surge that arguably might not be the same level
if we had also not managed to kill off two
whole species of rodents on the island. True, and there's
going to be even more stuff along those lines coming up.
So there are actually multiple ongoing threats to the life
(33:57):
cycle of these amazing animals. If if you care about
out the beauty of the crab army scuttling through the forests,
you should care about these issues. One is climate related.
So there is a paper from in Global Change Biology
called Linking l Neino Local rainfall and migration timing in
a tropical migratory species by Alison K. Shaw and Catherine A.
(34:20):
Kelly and the authors here find that species whose mating
and migratory behaviors are determined by weather, like the Christmas
Island red crab, remember it's the it's certain things about
the beginning of the rainy season that tell them time
to go to the beach and mate. Uh, they will
probably be adversely affected by the way climate change is
(34:41):
upsetting normal weather patterns that were used to so the
author's write quote. We find that the timing of the
annual crab breeding migration is closely related to the amount
of rain that falls during a migration window period prior
to potential egg release dates, which is in turn really
added to the Southern oscillation index and atmospheric l ne
(35:03):
NEO Southern oscillation index. As reproduction in this species is
conditional on successful migration, they don't reproduce if they don't migrate,
major changes in migration patterns could have detrimental consequences for
the survival of the species. So, in other words, climate
change messes around with the amount of timing of the
rainfall on Christmas Island, and then the crabs get the
(35:26):
short end of the stick and could find themselves unable
to use their normal migration and breeding instincts in order
to produce the next generation. And this could also have
follow on effects with the animals that depend on these
migratory animals for food, like the Christmas Island red crab
is sort of a keystone species on the island in
many ways. One of the things we already mentioned is
(35:48):
that those whale sharks come to eat the Christmas Island
red crab larvae in the water. But another thing is,
as we mentioned, they maintain the state of the forest
by clearing leaf litter and clearing out other plants in
the undergrowth of the forest, and you know, and by
turning the soil right. Yeah, they're they're aerators. Now, there
is another culprit that is putting the Christmas Island red
(36:11):
crabs at risk, and that is yellow crazy ants crazy ants. Again,
it's different crazy ants somewhat. So we did an episode
about crazy ants before, but that was focused on a
completely different animal. We were mainly talking about the raspberry
crazy ant of the genus Nylandria. The yellow ant is
a totally different genus. It's an apolo lepus gracillips and
(36:32):
these are ants with a slender body, long legs, and
like the crazy ants in genus Nylanderia, they're also easily
recognized by these movement patterns that give them their name.
Their motion is sometimes described as frantic or erratic or crazy,
and like raspberry crazy ants, these ants can also form
what are known as super colonies, which means they build
(36:54):
separate but friendly nests which do not attack one another
and form a kind of web of allied ant armies
that can easily overwhelm the habitats that they spread to,
and so they're considered a very problematic invasive species like
other crazy ants. Also, they spray formic acid as a
defensive and offensive biological weapon, and formic acid is a
(37:17):
powerful chemical. Uh, it's apparently a potent poison against land crabs.
So you can imagine a bunch of ants come up
against one of these Christmas Island red crabs and the
ants spray formic acid in its eyes, in the segment
joints of the crabs, so you know, like getting in
the leg joints, and this can leave the crabs unable
to move or to survive. And then after the crabs die,
(37:39):
of course, the ants get a feast of crab meat
and this has had a huge impact on crab populations.
It's been estimated that in the last fifteen years the
ants have reduced the crab populations on the island by
as much as so local land crabs have been put
severely at risk by the yellow crazy ants. Interestingly, the
yellow crazy ants exist it on the island for many decades.
(38:01):
I think they were introduced sometime in the first half
of the twentieth century. I've seen estimates in the nineteen
teens or twenties around then. Uh, And they were on
the island a long time before they became so destructive
to the land crabs beginning around the nineteen nineties. So
what changed around the nineteen nineties. I was reading a
report that was put together by Parks Australia together with
(38:24):
Latrobe University, and it appears that it was only in
the nineteen nineties or so that these massive super colonies
of yellow crazy ants began forming. So what caused that change?
What happened then? H the author's point to the emergence
of a mutualism actually a symbiotic relationship, and this is
a mutualism between the yellow crazy ants and another group
(38:47):
of insects called scale insects. So it's like the like
the two enemies, they they forged a truce and and
then we're united against the forces of the crab. Yes,
so another non native species, the scale insects. What they
do is they cling to plant stems and they suck
the sap from the plants for energy, and they produce
(39:09):
a sugary waste product from their anal pores in the process.
And the ants love this sugary poop, they go straight
to the anal pores and they eat it up. So
they have formed this mutualistic protective relationship with the tree
sucking candy poopers. The scale insects suck from the trees,
they produce sugary poop. The yellow the yellow crazy ants
(39:30):
eat the sugary poop and they protect the scale insects.
And it appears that this emerging symbiosis between the yellow
crazy ants and the scale insects is related to the
ant's ability to form these ecologically devastating super colonies. But
here's so, then you take the question one step back, Well,
what caused this mutualism to begin in the first place. Uh,
(39:52):
the authors of this report don't know. They speculate that
changing rainfall patterns on Christmas Island, we're putting stress on
freeze and this made the sap more concentrated, which means
it's even more sugary goodness for the scale insects. And
this increases the population of the scale insects, which produces
more delicious sugary poop for their yellow ant friends, which
(40:15):
means more ants to protect the scale insects, which means
even more scale insects and then you get this dangerous
feedback loop. It's this is all Christmas Island is in
so many ways. This uh, this wonderful look at the
horrible cascading effects of colonialism, of human intervention in general,
I mean at the macroscopic climate level and at the
(40:37):
local invasive level. Yet like at every level, we have
messed with this island. And we messed it with it
in one way, and now we're messing with it in
a different way, and and now in fact we're gonna
keep messing with it in order to try to fix
part of what we did. Because the question is can
anything be done to save these amazing red crabs. I mean,
these are it is a wonderful thing to see these
(41:00):
animals doing what they do. And so I was reading
an interesting article about this on the Conversation in UH
posted in by two Latrobe University professors Susan Lawler and
Peter Green, and apparently Parks Australia has been trying to
do all kinds of things to help the crabs survive
the crazy ants, or to knock the crazy ant super
colonies back, like they tried poison bading the ants by hand,
(41:23):
but apparently this is just not an efficient solution. In
sen they launched a new project, and this was killer wasps.
Like it tell me more so the killer wasps. They're
only about two millimeters long and they're naturally found in
India and Southeast Asia. They're called tach Cardiaphagus summer Villy
and the author selected this tiny wasp because it attacks
(41:45):
this specific species of scale insect that has formed the
mutualistic relationship with the crazy ants. Uh So, the wasp
is a parasitoid that lays its eggs in the body
of the female of this one species of scale insect,
which hatch into more wasps that lay more eggs in
these species of scale insects, and hopefully this will severely
(42:09):
control the population of this one particular species of scale insect,
which is also invasive on the island. Uh And the
authors note that they've had to be very cautious because
they cite examples that, you know, in the past, we've
tried to introduce animals to places in the hope that
they would control a pest problem, but then they became
a problem in their own right. They said, the example
(42:30):
of the cane toad in Australia, which was brought into
control cane beetles, but then it became its own kind
of problem. And I'm reminded, of course, of the old
nursery rhyme. There was an old lady who swallowed a fly, right,
and she's forced to keep swallowing progressively larger and parasitic
wasps and larger and more destructive organisms to try and
(42:51):
uh savor until if she dies at the end of
the song. Yeah, well, the authors, so we hope that
doesn't happen. The authors claim they performed rigorous research before
and uh they tested really hard to make sure this
wasp would not harm other local species, and they said,
you know, according to their tests, everything seemed to check out.
So they introduced the wasps in sixteen. And I checked
(43:12):
with a more recent news article on the wasp control
project from it looks like the effort is having early
markers for success. The wasps have become established, their range
is spreading, But we'll have to wait a few more
years before we see the full effect on the crab populations.
But I hope it works, and I hope it doesn't
have any unexpected effects. Less to become island of the
Wasps Kingdom of the Wasps. You don't want to have
(43:35):
to think about Crab Island needing to be protected. You
want to think that Crab Island is an armored, claw
wielding force to be reckoned with, and that it you know,
it can withstand anything on its own. But I don't know. Yeah,
natural populations or even unnatural populations are vulnerable. I mean,
look at Skull Island right King Kong's homeland. Oh, I
(43:58):
don't know anything about population dynam There a monster island
where all the giant Japanese monsters with That's clearly these
are places that need to be protected. We don't need
to go in there and try and defeat them with
our robots. Is there is there a crab kaiju? Yes?
There are. There are crab kaiju up the wazoo. Yes. Nice,
(44:19):
They have their own movies sometimes. Yeah, Godzillafat want to
forget its name? I cannot. I can never remember the
names of the adversary except that maybe it But yeah,
he fought a giant crab in one episode. It was
I finally remember it from my childhood. But we'll get
into We'll get into monster crabs a bit more in
the next episode of Stuff to Blow Your Mind, because
(44:40):
we will talk about another resident of Christmas Island that
is an enormous deco pod. In fact, that the largest
land crab that you will find on Earth. Now, naturally
we would love to hear from everybody out there. We
have listeners all over the world. I wonder if we
have just a single listener that lives on Christmas Island
(45:02):
if we do email us yes, Likewise, we have a
lot of Australian listeners uh and just listeners who have
traveled around the world. In general, if you have ever
been to Christmas Island and witnessed any of the species
we discussed here, or just I mean even if you've
just been there and you saw nothing at all, we
want to hear from you. Whatever you have to share
about Christmas Island would be gratefully appreciated. And in the meantime,
(45:25):
you can check out all the episodes of Stuff to
Blow Your Mind. It's Stuff to Blow your Mind dot com.
That's where you'll find all the episodes, links out to
our various social media accounts, including uh the discussion module,
which is our group on Facebook. Look up Stuff to
Blow your Mind Discussion Module and you can easily join
that and interact with other listeners as as as well
(45:45):
as Joe and myself. The website stuff to Blow Your
Mind dot com also has a link to our store
where you can buy some cool merchandise stickers, shirts, etcetera. Um,
it's probably probably a bit late now for for Christmas gifts,
at least for this Christmas. At hey, you can go
ahead and start start banking ahead for next year. It's
a great way to support the show, and if you
want to support the show without spending a dime, well
(46:07):
you can simply rate and review us wherever you have
the power to do so. Huge thanks as always to
our excellent audio producers Alex Williams and Torry Harrison. If
you would like to get in touch with this directly
to let us know feedback on this episode or any other,
to suggest topic for the future, or just to say hi,
let us know where you listen from that kind of thing,
you can email us at blow the Mind at how
(46:28):
stuff works dot com for more on this and thousands
of other topics. Is it how stuff works dot com
(47:01):
must as a tame baby a pro
Towards the Island of Christmas, and all across the land
the red crabs were flowing across root Street and sand
like a red tide of scuttling, claw snapping doom. They
streamed through my front door and into my rooms. Meanwhile,
in the forests the giants, they're crawled coconut crabs, hulking
monsters with claws. They hunted for carrion crab bird and
(00:26):
ratted and gobbled it up, rancid, sinew and fat. Welcome
to Stuff to Blow your Mind from how Stuff Works
dot Com. Hey, welcome to Stuff to Blow your Mind.
(00:46):
My name is Robert Lamb, and I'm Joe McCormick, and
getting in that holiday spirit. We're gonna be talking about
crab Horror. Yes, this is this pair of episodes. I've
been looking forward to all year. This has been my
my goal. I forget when, but earlier in the year
I was reading about Christmas Island and and the various
creatures that that call it home, and I realized, we
(01:09):
have to do this episode for Christmas, even though this
really has nothing to do with Christmas, no, virtually nothing
to do with Christmas, though I do enjoy um like
forcing decapods upon Christmas and uh and and and at
least in my mind, allowing them to take over the
holiday decapods with bows of all? Is it bows? I
(01:30):
should have said clause of glory? Either way, I appreciate
the holiday zeal. Now, so we're going to be going
to crab Horror Island, and there are many wonderful movies
and maybe we'll save it for next time to talk
about our favorite Crab Island movies. But the giant crab
is one of my favorite kind of movie monsters, and
they've always got to have their own island of terror,
(01:52):
right right, and and so in discussing Christmas Island and
these two episodes, we're going to talk about crabs or
you know, decapods anyway that are either enormous, uh, singularly
and enormous or collectively enormous. I think the first episode
we're going to focus on the collectively enormous, and the
second episode will focus on the decapods who are individually enormous. Now,
(02:15):
this first episode is going to focus on the Christmas
Island Red crab. Robert, will you take me on a
mystical adventure to crab Horror Island? Yes, we're talking about
Christmas Island, so named. It's in the Indian Ocean, about
three hundred and fifty kilometers or two hundred and twenty
miles south of Java and Sumatra and around uh, let's
(02:36):
see one thou fifty kilometers or nine hundred and sixty
miles northwest of the closest point on the Australian mainland.
Technically part of Australia though right it is an Australian
external territory. It has an area of a hundred five
square kilometers or fifty two square miles, so not huge, No,
not a big place at all. It's a very old,
(02:56):
though very old volcanic seamount island. It was first visited
by Europeans in sixty three Captain William Minors of the
Royal Mary and English East India Company vessel. He just
named the island when he sailed past it on Christmas
Day of that year. That's that's the only Christmas high
end there he didn't find, you know, and naturally occurring
(03:19):
Christmas tree there. Uh, there's no wasn't where the elf
workshop was exactly. There's there's nothing else about it except
it was Christmas Day when he found it. It could
have easily it could have easily turned out to be
Christmas Eve Island or Boxing Day Island or Halloween Island.
That would perhaps be a little more appropriate. Yeah. Uh So.
(03:39):
One of the cool things about this place is that
when when they were able to take a closer look
at it, they realized that it was uninhabited, at least
by humans. So it's obvious that what makes this island
unique is not anything about the indigenous culture or anything,
since it was apparently uninhabited originally, but it was not
uninhabited by wildlife. Fest we've made clear the wildlife there
(04:02):
was of a terrific scuttling variety, oh correct. And one
of the really cool things about the scuttling life on
Christmas Island it is that so much of it is
on Christmas Island. We're talking about land crabs, crabs that
need only returned to the water to mate, but mostly
live on land. And you'll find these elsewhere. To be sure,
this is not the only place land crabs can be found.
(04:23):
Uh And we're we're talking about both true crabs as
well as hermit crabs here. Hermit crabs are decapods, but
not true crabs. But forgive us as we as we
talk about them in these episodes, I will probably end
up calling them both crabs in the unofficial sense. The
Christmas Island is home to more land crabs than anywhere
else on Earth. We're talking more than twenty terrestrial and
(04:46):
semi terrestrial crabs species, plus a hundred and sixties species
or thereabouts in the reefs and shallows around the island. Yeah,
so Robert tell me a little bit about crabs. Well,
just to refresh everybody, crabs are crustaceans. But we should
be clear that again, there are true crabs of the
decapoda soap order bracci ura, which means small tail um,
(05:07):
which references their smaller abdomen. And then there are the
ano mora or mixed tail crabs, which included hermits and
as we'll discuss later in the second episode, robber crabs.
But still again we're often going to refer to them
both as crabs in the unofficial sense. And these were
these are ancient creatures. These were the first animals to
(05:27):
develop true legs, none of those false legs. Yeah, I mean,
we we've talked about crabs on the show before. I
think back to our episode about Carl Sagan and the
Samurai Crabs. So so hopefully everyone is is on board
for two more episodes of of crab based content. But
so it's not just the varieties of crab and crab
(05:49):
like creatures that live on Christmas Island that make it
crab Island Earth, Uh, it is is the number of
a particular species of crab there, the Christmas Silelan red crab,
where there are supposedly tens of millions of these crabs
on the island. And this is not a big island. Remember,
it's a hundred thirty five square kilometers, right, a small island.
(06:12):
And yet yeah, I've seen the figures of like fifty
million of these creatures living, living in the forest, living,
you know, pretty much all over the island. And that's
a reduced number. I remember we watched a documentary about
the island from the nineteen eighties that suggested, at the
time it was believed that there were over a hundred
million of the crabs. They're right. That was a night
David Attenborough narrated special titled Kingdom of the Crab, great title,
(06:37):
and that's a great one to watch if you get
a chance, because it really shows off what makes this
island visually astounding, but it's the sheer numbers of the
crabs and the Christmas Island red crab is pretty much
found only on Christmas Island. Yeah, I think maybe on
another nearby island or island group, but they're not found
like all over the place. So I do want to
(06:58):
come back to the human history for a little bit
where we we explore the red uh crab in depth.
So the most you know, essential thing about human history
of Christmas Island is that for the longest there seems
to have been none. It is a geographically isolated place
now from everything I've read so far, and it's always
possible on missing something, but there's no evidence that humans
(07:20):
ever visited the place before the seventeenth century. See this.
Despite Java being again only two miles away, it's a
short enough distance for modern humans anyway that boats of
asylum seekers frequently make it their point of destination in
reaching Australia, because again it's an Australian external territory, So
if you reach Christmas Island, you are, you know, in
(07:41):
a legal sense, in Australia. However, it's also worth pointing
out that the seas can be deadly uh, surrounding Christmas Island,
and there are stories out there boats of asylum seekers
breaking on the rocky coast with lethal results. I think
I've read about this in cases of the early visitors
to the island. Also that you know, it was kind
of dangerous to land there. And for example, there was
(08:03):
one case where I read that a crew was driven
to land there because there was scurvy on the ship
and it was only because the disease had gotten so
bad that they risked trying to land. Yeah, that's sort
of the typical story book reasons for landing on an
uninhabited island with a strange crab population. Yeah, but out
of the scurvy pan into the crabs. Yeah, and you
(08:23):
know it, but but it is. It is weird to
think about places like this, places where where humans just
didn't take up residents. And of course you have to,
of course realize that moving to an isolated island is
a difficult proposition, like you've really got to have a
reason to go there and a reason to stay there,
and a way to um to to safely arrived there
(08:45):
as well. But still, you know, it's enough to make
one wonder. For instance, Homo Erectus or a Java Man
lived on the island of Java, relatively close by one
point seven million years ago. Humans practiced agriculture there on
Java as early as b C. Java was known to
traders and other powers. The Kingdom of Mataram ruled there
(09:08):
until they lost power to the Dutch East India Company
in seventy nine and became a vassal state of the
company UM, a statement that I think really drives home
the power of the East India Company UM, the idea
that you would have a vassal state to a corporation.
But that's a job. My point is that I just
(09:28):
find it so enthralling that this island remained either free
of human contact for so long or only encountered minimal influence.
You know. It's I guess it's possible that it's at
some point somebody wound up there by purpose or accident
and didn't didn't stay long enough to leave a footprint,
you know. Galapagos Islands or another example of this, though
(09:48):
there there have been at least disputed claims of Inca
artifacts found on the Galapacos Islands, perhaps due to Inca
sailors being blown off course. The statials in the Indian
Ocean and are another example of islands that were uninhabited
through most of recorded history, though they may have been
visited by early seafares as well, depending on who you
talked to. But with Christmas Island, I found no such thing,
(10:10):
and not even a crackpot theory. So it really does
seem as if humans, not even the Vikings, went their
theory by no Vikings or anything. So it really does
seem that nobody visited it until the seventeenth century, with
the earliest sighting I think having occurred in sixteen fifteen.
Now after that, of course, it actually did become an
economically significant island because of mineral deposits discovered there. That's right.
(10:34):
It was explored by British naturalist John Murray, and this
was eighteen seventy two. He discovered that there were phosphate
deposits on the island, which would play a key role
in the island's future. Exportation of phosphate begin in eighteen
by the Christmas Island Phosphate Company, and this activity led
to the loss of twenty of the island's rainforest area. Yeah, Now,
(10:58):
phosphate was important in the late eight hundreds because it
had been discovered by that time that phosphate, when treated
with sulfuric acid, could be used as an ingredient in
plant food, and of course synthetic fertilizers became very important
in the development of commercial agriculture at scale, and so
now there was a reason and economic reason for people
to not only go to Christmas Island but to work there,
(11:22):
and so settlement began in the eighteen eighties. Uh later on,
during the Second World War there was a Japanese occupation
of the island from ninety five, and in the post
war period it was administered by Singapore, which was then
a British colony, and then Australia purchased the island for
two point nine million pounds on January one, nineteen fifty
(11:43):
eight day that's known as Territory Day on Christmas Island.
Today it has around I've read two thousand full time
human residents and the ethnic makeup is mostly Chinese in
meleay Um originally brought in for labor. Now a big
poor scan of the land of the island today is
basically a national park. It's like a big wildlife preservation area. Yeah,
(12:08):
two thirds of its land mass are national park. Now,
and a big part of the wildlife significance here is
the Christmas Island red crabs. So I guess we should
dive headfirst into a puddle of crabs after we come
back from a break. Alright, we're back, so it is
time to dive into a pit of crabs. The Christmas
Island red crab or get Karcodia natalis. And these are
(12:32):
crabs that live, as we mentioned earlier, primarily not in
the ocean, not even on the shoreline, but in inland forests.
So if you picture Christmas Island, it's sort of a
terraced rainforest. It's a you know, volcanic island. It's got
some steep slopes that go up onto rainforest covered terraces,
and the crabs go all the way up into the
(12:53):
forests and make their burrows inland. Yeah, we're talking against
something like fifty million of these a little land well
ers uh in the forest chewing up leaf litter. And
here on Christmas Island they are the chief decay agents
for that leaf litter. I've seen estimates of something like
four thousand crabs per acre to keep the leaf litter down. Yes,
(13:14):
and they primarily feed on plant matter like you say,
so that is going to be leaf litter. It's also
things like fallen fruits and seeds, flowers, et cetera. But
they're also crabs after all, so you might not be
surprised to learn that they are opportunistic omnivores. My favorite
pairs of words. So if you get a little bit
(13:34):
of meat from say another dead red crab or something
like that presenting itself, this is a legitimate score, and
they will say, gentlemen, get that in my mouth parts.
It's time to masticate. But the crabs are important for
the maintenance of the ecosystem in multiple ways. So they
clear the forest floor of like leaf litter, but also
saplings and flowers other plants that would create dense underbrush,
(13:58):
and so they keep the forest floors lean, and this
actually helps contribute to forest biodiversity. They also prevent the
soil from being packed too densely because of the burrows
they dig. They're like natural soil tillers. They turn the soil,
and this also helps contribute to forest biodiversity. But so
we might have a pretty good sense of what the
(14:19):
life of an ocean dwelling crab is like. What is
the life of a land crab like crabs, as you
can imagine, in between chewing up things in their environment
and eating it, they have to stay moist and this means,
for one thing, staying out of the direct sun. So
the red crabs on Christmas Island like to stay in
the shady forests and they live in these dugout burrows
that they can hide from the sun in and they
(14:41):
have guilt chambers that have adapted for terrestrial life. They
have to keep them moist, and they also I love this,
they have to manually wet their eye stalks. Yes, I
love this. It's pretty cool to watch if you can
find video of this. So their eyes talks emerge from
little cups in their carapace, and they don't have eyelids
of course, and by the way, just try to imagine
life without eyelids. Kind of a terror. So they wet
(15:05):
and wash their eyes by filling their eye cups up
with drops of water and then dipping their eyestalks down
into the cups to rinse them off. Yeah. I think
this is This is one of the great things about
watching any crab close up, but especially with the Christmas
crabs is those tiny little sort of methodical movements that
(15:25):
you see take place with their mouth parts and their
their eyes stalks totally. Now, despite their life in the woods,
they still have to return to the sea to spawn,
and this results in a vast scuttling migration that is
truly unlike anything else on earth. This is why you
will you will see. You know, there's so many different
documentaries about Christmas Island. That's why there's so much great
(15:47):
footage because they they go on these enormous migrations and
we're talking a several kilometer journey each year. Yeah, this
is crab Apocalypse. This is where the real show is
on Christmas Eye. And so around the beginning of the
rainy season, which is sometime October through December, the red
crabs begin this migration for their breeding cycle. And the
(16:10):
migration begins with the males, usually the biggest males, who
will crawl out over land from their forest burrows to
the shore where they're going to eventually get there and
dig new burrows for mating. And as the males make
this journey, the females eventually joined them in the journey
and they march towards the sea. Now, once the crabs
(16:30):
reached the shore, but before they dig their burrows to mate, uh,
they typically wash themselves off in seawater, though strangely enough,
they have to be careful not to get fully sucked
out into the sea because these are land dwelling crabs.
This is how they've evolved, and they can neither breathe underwater,
nor can they swim very well. These are crabs who
(16:50):
are not very good at being crabs. Yeah, so the
truly aquatic crabs in the neighborhood are just probably watching
this in halfing at them. But there's so many of them.
How could you laugh at them? Because they could really
gang up on you if they got a hold of
your right But so they would rinse themselves off in
the sea water. And then the males dig the burrows. Now,
(17:11):
sometimes when they dig the burrows, usually they'll go up
a little bit from the beach and one of the
forested areas just right by the beach, and they'll dig
these burrows. And sometimes the males have to defend their
burrows from other males, who of course think, hey, why
dig one when you can just claim somebody else's. So
there are sometimes these fights and dominance displays, a lot
of claw waving to keep the burrows secure, and then
(17:34):
of course the females come in and they will find
a male with a burrow and initiate the mating. And
by the way, if you've never watched crabs mating before,
it's one of the funnier looking types of animal sex.
I think it's just crabs look funny no matter what
they're doing. But also if you can just watch their
eyes while they're mating, it's really something special. It's you know,
(17:58):
it's like two googly eyed robots trying to be sexy
at each other and then throwing some claws and swiveling
mouth parts. It's just awesome. Now you mentioned the waving
of the clause, I want to I was reading a
little bit about crab clause in Douglas j Imland's book
Animal Weapons. Uh and he goes. He spends a little
bit of time talking about, you know, how these are
high energy adaptations packed with powerful muscles. They need to
(18:19):
be able to break through the exo skeletons of of
rival males in many cases. Uh And he mostly looks
at fiddler crabs in this book. But but, but it's
interesting stuff. The economics of not only having growing, evolving
gigantic class, but waving them around, because that's that's part
of having the cleaving clause or a claw, is to
(18:39):
wave that sucker around, yeah, or like flexing your muscles,
like showing off the guns. Yeah, you have to show
off the guns. That's that's part of having them, right. Yeah.
So the female will generally find a male and a
male with the borrow and they will mate, and then
after mating, what the males do is they just pack
up and headback inland. Their work is done, and they
(19:01):
leave the females by themselves in the seaside burrows. And
there's another interesting thing about this. Okay, so the red
crabs are sort of moon worshiping druids. The breeding migration
has to be timed exactly according to the cycle of
the moon because the cycle of the moon affects the tides.
So the adult crabs arrive at the shore and then
(19:23):
they mate, and after mating, the females produce eggs within
about three days, and then they remain in their burrows
for another twelve or thirteen days. And after this they
emerge from the hole in the ground and they release
their eggs into the sea water. And it has to
be timed exactly at the turn of high tide as
the moon goes from its last quarter to a new moon.
(19:45):
And this is because it's when the tide conditions are
just right to be releasing uh the young. But if
the migration is delayed by weather so that breeding can't
be timed exactly right with the phases of the moon,
the crabs will just wait. They'll just wait until the
next month to breed because it's not it's not going
the moon isn't right. So when the time is right,
the females release their eggs acts, which looks kind of
(20:07):
like a weird foamy sponge that they carry on the
underside of their bodies. They release these eggs acts into
the water. Yet again, I can't help but notice that
my wonder at these animals is combined with hilarity on
seeing this, because in some cases, the female crabs have
to release their eggs into like rough surf while clinging
to rocks above the water, and they're trying to be
(20:29):
careful not to fall in. And when you see footage
of this, the way they're just frantically shaking their bodies
to knock the eggs acts off, dumping thousands of eggs
off a cliff. I can't help but laugh. It's funny.
And then also sometimes they'll they'll go into the surf
on a beach and you'll see them like raising their
claws and shaking their bodies, like get off, just dumping
(20:52):
all these eggs off into the water. I don't know,
it's it's funny to me. Well, by human comparisons, they're
maybe not great moms, but by but by Christmas Island
Red Crab standards, moms of the Year. Yeah, exactly, and
that this does make me think about the ways that
we anthropomorphize good parenting. I want to come back to
that in just a minute. So the eggs are released
(21:12):
into the surf and they hatch pretty much immediately, and
then you've got these hatchling crab larvae that live in
the water for about a month, transforming through large larval stages,
and then they returned the shore in this seething foam
of what looks like pink ants. This is also just
astonishing to see, like the original migration from the forest
(21:33):
to the shore with the beaches and rocks covered in
this surging pink shag carpet of tiny millimeter sized baby crabs.
And then they molt, and immediately after molting, they they
are committed to an air breathing life on land, and
they travel inland to do as their ancestors did before them.
And this growth from about a five millimeter baby crab
(21:55):
stage to adulthood usually takes about four years, during which
time they mostly tend to hide out undercover until they
get big enough to fend for themselves. But yeah, back
to this idea about the way we look at non
human animals and tend to to judge their parenting. I mean,
that's inherently what I was doing when I think it's
funny just watching the mother crabs chuck their eggs off
(22:17):
a cliff. But it's like it's hilarious watching a crab
vigorously shake its body to knock all the eggs off
and stuff. But it's because we've so deeply internalized the
brood protection tendencies of mammals. Mammals tend to keep their
offspring close and take care of them for for like
extended periods of time while they mature, and that would
(22:38):
make no sense for crabs to do. First of all,
of course, it is just mechanically the case, because the
eggs need to hatch in the water. That's what chemically
and mechanically they do, but also mathematically, the parents have
a totally different relationship with their offspring. Mammals tend to produce,
you know, relatively small numbers of offspring and invest a
lot of energy into caring for and protecting them. But
(23:01):
I was trying to do a little bit of rough
math about the red crabs. So let's assume there are
fifty million adult red crabs on the island, and then
you've got mated pairs, and each mated pair of adult
crabs produces tens of thousands of eggs. I've seen a
common figure of a hundred thousand eggs per female crab sited.
So if fifty million crabs made it and produced twenty
(23:23):
five million eggs sponges, and each of those had a
hundred thousand eggs in it, and all those eggs survived
to adulthood, that would be two trillion, five hundred billion crabs. Now,
Christmas Island is about a hundred and thirty five square kilometers.
If my math is right, this means that just after
one year there would be a Christmas Island would have
(23:44):
eighteen point five billion crabs per square kilometer. So you're saying,
as a red crab mom, you have to be willing
to let some of those crabs go because you have
you have the numbers on your side, right. I mean,
it's just a totally different way of of have a
relationship between generations, right. They're going for for numbers. You know,
it's quantity rather than quality. And it's just impossible for
(24:07):
all those young to sustainably survive. Even if a decent
fraction of them survived, it would be ridiculous. Only a
tiny fraction of them can possibly make it to adulthood
in any ecologically sustainable way. And so most that get
dumped out into the water to hatch never make it
back to shore alive. They get washed out to sea,
never to return. Apparently, whale sharks migrate to the Christmas
(24:30):
Island area to eat red crab larvae when they hatch,
and among those that do make it back to the
beach in that in that you know foamy pink shag
carpet I mentioned, they're obviously going to be pretty easy
prey at that stage too. You can even sometimes see
I've seen footage of this of adult red crabs just
kind of shoveling clawfulls of young red crabs into their mouths,
(24:51):
because hey, what are the chances that these are mine?
It's pretty slim. Again, it's a numbers game. Well. Plus,
it's like they're just against so many of them. It's
like if you make way too much a pancake batter, Uh,
you may treat yourself to a few spoonfuls of unclid
pancake batter. I mean, why not, it's there. You can
only make so many pancakes. You can make similar argument.
You'd be like, look, if I made all of this
(25:13):
into pancakes, our house would be packed with pancakes six
ft high exactly. But anyway, given this kind of life cycle,
in these kind of odds, the way to be a
good parent is to do exactly what the female crabs do.
They shake them off into the water where they've got
a chance, and then they call it a day. There's
nothing more you can do at that point. And if
somehow you were still around when they hatched and molted,
(25:35):
who knows, you might just gobble them up. So, despite
how funny it looks, I rebuke my instincts. I do
not think that the red crabs are bad parents. I
think they're awesome crab parents. All right, we're gonna take
a quick break, and when we come back, we're going
to get into the human element. What happens when we
have the human element to the red crab element. Thank alright,
(25:55):
we're back now. We discussed earlier how crazy these migrations are.
You when the island can, sometimes in areas, become just
thick with crabs that are moving from forest to shore
or returning from shore to forest. And this doesn't even
take into consideration the fact that sometimes there are multiple
waves of migration during the same year. So you've got
(26:17):
crabs going both ways. Like one set of crabs they
moved down to the shore, and then there's another, uh
you know, trigger of the rainy season, another set of
crabs they start moving to the shore, and then the
other ones are going home. So you can have crabs
going this way, crabs going that way. There on the
golf course, there on the streets, there in the grocery store.
I mean, it can become quite thick with crabs on
(26:39):
Christmas Island. And yet there are people here, that's right,
and those people have vehicles that they also have pets. Uh,
we'll get into some of those complications in a bit,
but just the roads. You're talking about something like a
million crabs a year crushed by road traffic on Christmas Island,
but that's still only gonna shake out to something like
one percent of the population. And the dead, by the way,
(27:02):
are apparently swiftly cannibalized. Again, crabs. Crabs are gonna do
what crabs are gonna do. No. I mentioned earlier that
there's this great old British TV documentary called Kingdom of
the Crabs and narrated by David Attenborough from nineteen I think, yeah,
that was the same year that we got John Carpenters
They Live, Killer Clowns from Outer Space, The Blob the remake,
(27:24):
the really cool eighties remake, as well as of course
Mac and Me. Well, this is right up there with those.
But it's got so many great moments. And one of
the best moments from it is when you're watching hundreds
of crabs scuttling across a pair of railroad tracks and
then a train emerges in the background and it's barreling
towards the crab crossing, and then the crabs show no
(27:45):
sign of getting out of the way, and then the
train conductor starts blowing his horn at the crabs as
if that's going to deter them. I guess it's like
when people like they stop in the road because the
turtle is crossing and they honked their horn at it.
I never actually haunt my hornets, they squirrels, chipmunks, but
I will almost wreck my vehicle to avoid them. But
(28:07):
I I guess that's human nature. Like you don't want
to squish crabs unnecessarily. I mean maybe some people do.
There are probably a few people on the island who
kind of get off on it. Well, I've read that
it can. It can also hurt your tires. Yeah, you
have people with flat tires due to the crabs. Probably
hurts trains less, probably, Uh. But the humans have had
(28:28):
to put in place many steps to help the crabs
cope with roads and tracks and the other ways that
we have unfortunately disrupted their migration zones. I mean, it's
not the crabs fault, right, They didn't ask us to
put a road there, but railroad tracks there to do
all that kind of stuff. So these adaptations are are
pretty interesting. They include barriers of course around the edges
(28:50):
of roads and put walls around the roads to keep
the crabs from walking onto the roads, and these lead
to sort of crab funnels that route the crabs to
specially designs safe crossings, so you might have an underpass
with a great on top of it, or even there's
even a five meter high crab bridge climbable by crab
to help them over one stretch of road. Oh yeah,
(29:12):
and you included a picture of these in our notes.
It's pretty incredible because it looks like one of the
recognizers those enemy ships in the Tron movies. Yeah, it
looks like like that the big clamp that comes down
on top of you, right, except instead of being made
out of brightly colored light, it's covered in brightly colored
red crabs right now. Interestingly enough, early accounts of Christmas
(29:35):
Island make no real mention of the crab hoardz. So
you could you can look at that one of two ways, right, Well,
either it didn't occur in this at least with the
same at the same level, or they just forgot to
mention it, which seems unlikely, but maybe they didn't witness it. Well,
it's true too, but there is this suspected link between
(29:57):
the current levels and the decent levels of of of
the red crab population with the extinction of two species
of rat that were on the island when Europeans first arrived.
And uh, and it's possible that these two species of
rat may have kept the populations more in check. What
(30:18):
are these rats alright? One is called mcclear's rat or
memor Rattis McCleary and the other is the bulldog rat
or Rattus nativitatis. And those are just two of only
five native mammal species on Christmas Island to have been
officially listed as extinct since human showed up. That being
(30:39):
both of these rats, and the reason that they went extinct,
it's it's probably because exotic rodents were brought in by
early human colonizers or brought in. I would say they
just came along with let rats do. Okay, So the
ideas that humans brought different kinds of rodents, those rodents
out competed the native rodents, but those rodents weren't as
(31:00):
much of a competition with the red crabs. Well, it's
more than just outcompete as apparently like straight up killed
them off with illness. It was looking at a two
thousand eight study published in PLS one, and they pointed
out that there seems to be a direct cause here
and it seems to be disease. They collected DNA samples
from the islands now extinct native rats via late nineteenth
(31:23):
and early twentieth century museum specimens, and they attributed the
extinction event here to ship jumping black rats infected with
the protozoan Tripenasoma louizy, an organism that is related to
an organism that causes sleeping sickness in humans. And indeed,
native Island rats were seen to stagger around following the
(31:46):
arrival of the s S Hindustan in eight and this
protozoan is light is likely spread by fleas, so we
have you know, it's a similar situation that we've seen
with certainly with with human populations and UH and other organisms,
where an exotic variant brought in a parasite that the
UH that the native inhabitants were just simply unable to
(32:08):
deal with. Now, in terms of other native Christmas Island mammals,
others have had a tough time as well. The Christmas
Island shrew is critically endangered. There's also a particular bat
the Christmas Island PIPISTRELLI, Yes, thank you for helping that one. Now,
(32:30):
it's it's name. It is a cute name, a cute
name for a bat. It's critically endangered, if not outright extinct,
and apparently the reasoning behind that is is not completely understood.
There's also the Christmas Island flying fox, which is another
type of bat. It is also in decline for unknown reasons.
And then you have the exotic mammals. We've already mentioned
(32:51):
black rats, but you also have a house mice, you
have feral cats and wild dogs. Now do we know
what the explicit relationship between that change in the mammal
populations and the surge and crabs is. The belief is
that those populated the original populations of rodents were helping
to keep the population of crabs in check, and apparently
(33:13):
the the the exotic mammals have not been able to
keep their numbers in check the same in the same rate.
I see, So they're not adapted to to crab Island, right, Yeah,
it's it's one of those situations where again you just
see humans show up in the unbalanced things. Now, in
the case of the red crabs, it would almost seem
like the unbalancing made more spectacle right, Like the reason
(33:36):
we're talking about Christmas Island is because we have this
enormous surge that arguably might not be the same level
if we had also not managed to kill off two
whole species of rodents on the island. True, and there's
going to be even more stuff along those lines coming up.
So there are actually multiple ongoing threats to the life
(33:57):
cycle of these amazing animals. If if you care about
out the beauty of the crab army scuttling through the forests,
you should care about these issues. One is climate related.
So there is a paper from in Global Change Biology
called Linking l Neino Local rainfall and migration timing in
a tropical migratory species by Alison K. Shaw and Catherine A.
(34:20):
Kelly and the authors here find that species whose mating
and migratory behaviors are determined by weather, like the Christmas
Island red crab, remember it's the it's certain things about
the beginning of the rainy season that tell them time
to go to the beach and mate. Uh, they will
probably be adversely affected by the way climate change is
(34:41):
upsetting normal weather patterns that were used to so the
author's write quote. We find that the timing of the
annual crab breeding migration is closely related to the amount
of rain that falls during a migration window period prior
to potential egg release dates, which is in turn really
added to the Southern oscillation index and atmospheric l ne
(35:03):
NEO Southern oscillation index. As reproduction in this species is
conditional on successful migration, they don't reproduce if they don't migrate,
major changes in migration patterns could have detrimental consequences for
the survival of the species. So, in other words, climate
change messes around with the amount of timing of the
rainfall on Christmas Island, and then the crabs get the
(35:26):
short end of the stick and could find themselves unable
to use their normal migration and breeding instincts in order
to produce the next generation. And this could also have
follow on effects with the animals that depend on these
migratory animals for food, like the Christmas Island red crab
is sort of a keystone species on the island in
many ways. One of the things we already mentioned is
(35:48):
that those whale sharks come to eat the Christmas Island
red crab larvae in the water. But another thing is,
as we mentioned, they maintain the state of the forest
by clearing leaf litter and clearing out other plants in
the undergrowth of the forest, and you know, and by
turning the soil right. Yeah, they're they're aerators. Now, there
is another culprit that is putting the Christmas Island red
(36:11):
crabs at risk, and that is yellow crazy ants crazy ants. Again,
it's different crazy ants somewhat. So we did an episode
about crazy ants before, but that was focused on a
completely different animal. We were mainly talking about the raspberry
crazy ant of the genus Nylandria. The yellow ant is
a totally different genus. It's an apolo lepus gracillips and
(36:32):
these are ants with a slender body, long legs, and
like the crazy ants in genus Nylanderia, they're also easily
recognized by these movement patterns that give them their name.
Their motion is sometimes described as frantic or erratic or crazy,
and like raspberry crazy ants, these ants can also form
what are known as super colonies, which means they build
(36:54):
separate but friendly nests which do not attack one another
and form a kind of web of allied ant armies
that can easily overwhelm the habitats that they spread to,
and so they're considered a very problematic invasive species like
other crazy ants. Also, they spray formic acid as a
defensive and offensive biological weapon, and formic acid is a
(37:17):
powerful chemical. Uh, it's apparently a potent poison against land crabs.
So you can imagine a bunch of ants come up
against one of these Christmas Island red crabs and the
ants spray formic acid in its eyes, in the segment
joints of the crabs, so you know, like getting in
the leg joints, and this can leave the crabs unable
to move or to survive. And then after the crabs die,
(37:39):
of course, the ants get a feast of crab meat
and this has had a huge impact on crab populations.
It's been estimated that in the last fifteen years the
ants have reduced the crab populations on the island by
as much as so local land crabs have been put
severely at risk by the yellow crazy ants. Interestingly, the
yellow crazy ants exist it on the island for many decades.
(38:01):
I think they were introduced sometime in the first half
of the twentieth century. I've seen estimates in the nineteen
teens or twenties around then. Uh, And they were on
the island a long time before they became so destructive
to the land crabs beginning around the nineteen nineties. So
what changed around the nineteen nineties. I was reading a
report that was put together by Parks Australia together with
(38:24):
Latrobe University, and it appears that it was only in
the nineteen nineties or so that these massive super colonies
of yellow crazy ants began forming. So what caused that change?
What happened then? H the author's point to the emergence
of a mutualism actually a symbiotic relationship, and this is
a mutualism between the yellow crazy ants and another group
(38:47):
of insects called scale insects. So it's like the like
the two enemies, they they forged a truce and and
then we're united against the forces of the crab. Yes,
so another non native species, the scale insects. What they
do is they cling to plant stems and they suck
the sap from the plants for energy, and they produce
(39:09):
a sugary waste product from their anal pores in the process.
And the ants love this sugary poop, they go straight
to the anal pores and they eat it up. So
they have formed this mutualistic protective relationship with the tree
sucking candy poopers. The scale insects suck from the trees,
they produce sugary poop. The yellow the yellow crazy ants
(39:30):
eat the sugary poop and they protect the scale insects.
And it appears that this emerging symbiosis between the yellow
crazy ants and the scale insects is related to the
ant's ability to form these ecologically devastating super colonies. But
here's so, then you take the question one step back, Well,
what caused this mutualism to begin in the first place. Uh,
(39:52):
the authors of this report don't know. They speculate that
changing rainfall patterns on Christmas Island, we're putting stress on
freeze and this made the sap more concentrated, which means
it's even more sugary goodness for the scale insects. And
this increases the population of the scale insects, which produces
more delicious sugary poop for their yellow ant friends, which
(40:15):
means more ants to protect the scale insects, which means
even more scale insects and then you get this dangerous
feedback loop. It's this is all Christmas Island is in
so many ways. This uh, this wonderful look at the
horrible cascading effects of colonialism, of human intervention in general,
I mean at the macroscopic climate level and at the
(40:37):
local invasive level. Yet like at every level, we have
messed with this island. And we messed it with it
in one way, and now we're messing with it in
a different way, and and now in fact we're gonna
keep messing with it in order to try to fix
part of what we did. Because the question is can
anything be done to save these amazing red crabs. I mean,
these are it is a wonderful thing to see these
(41:00):
animals doing what they do. And so I was reading
an interesting article about this on the Conversation in UH
posted in by two Latrobe University professors Susan Lawler and
Peter Green, and apparently Parks Australia has been trying to
do all kinds of things to help the crabs survive
the crazy ants, or to knock the crazy ant super
colonies back, like they tried poison bading the ants by hand,
(41:23):
but apparently this is just not an efficient solution. In
sen they launched a new project, and this was killer wasps.
Like it tell me more so the killer wasps. They're
only about two millimeters long and they're naturally found in
India and Southeast Asia. They're called tach Cardiaphagus summer Villy
and the author selected this tiny wasp because it attacks
(41:45):
this specific species of scale insect that has formed the
mutualistic relationship with the crazy ants. Uh So, the wasp
is a parasitoid that lays its eggs in the body
of the female of this one species of scale insect,
which hatch into more wasps that lay more eggs in
these species of scale insects, and hopefully this will severely
(42:09):
control the population of this one particular species of scale insect,
which is also invasive on the island. Uh And the
authors note that they've had to be very cautious because
they cite examples that, you know, in the past, we've
tried to introduce animals to places in the hope that
they would control a pest problem, but then they became
a problem in their own right. They said, the example
(42:30):
of the cane toad in Australia, which was brought into
control cane beetles, but then it became its own kind
of problem. And I'm reminded, of course, of the old
nursery rhyme. There was an old lady who swallowed a fly, right,
and she's forced to keep swallowing progressively larger and parasitic
wasps and larger and more destructive organisms to try and
(42:51):
uh savor until if she dies at the end of
the song. Yeah, well, the authors, so we hope that
doesn't happen. The authors claim they performed rigorous research before
and uh they tested really hard to make sure this
wasp would not harm other local species, and they said,
you know, according to their tests, everything seemed to check out.
So they introduced the wasps in sixteen. And I checked
(43:12):
with a more recent news article on the wasp control
project from it looks like the effort is having early
markers for success. The wasps have become established, their range
is spreading, But we'll have to wait a few more
years before we see the full effect on the crab populations.
But I hope it works, and I hope it doesn't
have any unexpected effects. Less to become island of the
Wasps Kingdom of the Wasps. You don't want to have
(43:35):
to think about Crab Island needing to be protected. You
want to think that Crab Island is an armored, claw
wielding force to be reckoned with, and that it you know,
it can withstand anything on its own. But I don't know. Yeah,
natural populations or even unnatural populations are vulnerable. I mean,
look at Skull Island right King Kong's homeland. Oh, I
(43:58):
don't know anything about population dynam There a monster island
where all the giant Japanese monsters with That's clearly these
are places that need to be protected. We don't need
to go in there and try and defeat them with
our robots. Is there is there a crab kaiju? Yes?
There are. There are crab kaiju up the wazoo. Yes. Nice,
(44:19):
They have their own movies sometimes. Yeah, Godzillafat want to
forget its name? I cannot. I can never remember the
names of the adversary except that maybe it But yeah,
he fought a giant crab in one episode. It was
I finally remember it from my childhood. But we'll get
into We'll get into monster crabs a bit more in
the next episode of Stuff to Blow Your Mind, because
(44:40):
we will talk about another resident of Christmas Island that
is an enormous deco pod. In fact, that the largest
land crab that you will find on Earth. Now, naturally
we would love to hear from everybody out there. We
have listeners all over the world. I wonder if we
have just a single listener that lives on Christmas Island
(45:02):
if we do email us yes, Likewise, we have a
lot of Australian listeners uh and just listeners who have
traveled around the world. In general, if you have ever
been to Christmas Island and witnessed any of the species
we discussed here, or just I mean even if you've
just been there and you saw nothing at all, we
want to hear from you. Whatever you have to share
about Christmas Island would be gratefully appreciated. And in the meantime,
(45:25):
you can check out all the episodes of Stuff to
Blow Your Mind. It's Stuff to Blow your Mind dot com.
That's where you'll find all the episodes, links out to
our various social media accounts, including uh the discussion module,
which is our group on Facebook. Look up Stuff to
Blow your Mind Discussion Module and you can easily join
that and interact with other listeners as as as well
(45:45):
as Joe and myself. The website stuff to Blow Your
Mind dot com also has a link to our store
where you can buy some cool merchandise stickers, shirts, etcetera. Um,
it's probably probably a bit late now for for Christmas gifts,
at least for this Christmas. At hey, you can go
ahead and start start banking ahead for next year. It's
a great way to support the show, and if you
want to support the show without spending a dime, well
(46:07):
you can simply rate and review us wherever you have
the power to do so. Huge thanks as always to
our excellent audio producers Alex Williams and Torry Harrison. If
you would like to get in touch with this directly
to let us know feedback on this episode or any other,
to suggest topic for the future, or just to say hi,
let us know where you listen from that kind of thing,
you can email us at blow the Mind at how
(46:28):
stuff works dot com for more on this and thousands
of other topics. Is it how stuff works dot com
(47:01):
must as a tame baby a pro
Stuff To Blow Your Mind News
Hosts And Creators
Robert Lamb
Joe McCormick
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
24/7 News: The Latest
The latest news in 4 minutes updated every hour, every day.
The Joe Rogan Experience
The official podcast of comedian Joe Rogan.