you've ever been to a pet store you
might have seen tiny hermit crabs
they're cute shy and live in adorable
enclosures but not every hermit crab is
that cute in faraway remote islands
lives a hermit crabs so large that even
Charles Darwin called it monstrous this
is the coconut crab hi I'm Daniel Defoe
and you're watching Animalia logic
coconut crabs or robber crabs get a bad
reputation because they're humongous
they have gigantic claws and they've
been seen eating birds and kittens but
if you get past all that there are
actually amazing creatures coconut crabs
are massive they can have a leg span of
over one meter and weigh over four
kilograms they're the largest land
invertebrate on earth and they might
have actually reached the current
physiological size limit for arthropods
back in the day there used to be larger
land arthropods such as the fearsome
arthropleura which go to be two and a
half meters long but as oxygen levels in
the air dropped their large bodies
became unsustainable as they're not as
good at absorbing oxygen as vertebrates
coconut crabs are the biggest land
arthropods that we have but if you want
to see them you might have to travel far
they're found on islands in the South
Pacific and the Indian Ocean with large
populations living on Christmas Island
and the Cook Islands their distribution
aligns nicely with the distribution of
the coconut palm even though coconuts
aren't their only food source they are
surprisingly great climbers and often
climb the palm trees to grab the
coconuts when possible they prefer to
eat fleshy fruit and nuts some of those
fruits including the sea mango have
toxins I get sequestered in the crabs
bodies and make the crabs poisonous to
humans they're asymmetrical claws are
among the largest in the animal kingdom
and for some reason their left is always
larger than the right south claws
represents coconut crabs have the
strongest claw grip in the animal
kingdom at 1500 Newtons they're helpful
for self-defence hunting and for opening
coconuts to do this they pull away the
outer fibers in a process that might
take days then they pierce holes through
the eyes of the coconut with their thin
and pointy legs
this makes the coconut easier to break
to access the meat coconuts are so
important to them that in areas without
coconuts they're about half the size of
coconut crabs from areas that have
coconuts though mostly vegetarian
coconut crabs will eat anything they can
get their claws on carrion rats birds
and other live animals are consumed when
they're available for mid-sized coconut
crabs they're only predators are humans
and larger coconut crabs in one
particularly gruesome case a coconut
crowd was observed eating a red footed
booby the crab was observed climbing a
tree in the middle of the night it
approached a sleeping red footed booby
and grabbed it by the wing breaking its
bone this caused the bird to fall to the
ground
crab followed it and grabbed the other
wing also breaking it the smell of blood
attracted 20 other coconut crabs which
proceeded to have booby for dinner huh
there's a morbid theory that the reason
why amelia earhart was never found was
because coconut crabs may have dragged
her into their burrows and eaten her
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their sense of smell on land is very
advanced compared to other crustaceans
and they have convergently evolved in
olfactory systems similar to insects
within 10 a full of chemoreceptors their
antennae help them find food but also
help them find potential Valentine's Day
dates which for them is between May and
September males depositor spermatophore
on the abdomen of the female she uses
this to fertilize her eggs which she
carries externally
when they're ready to hatch she goes to
the water and releases them when the
tide is high the babies live as plankton
for about a month fully dependent on
ocean currents for movement when they're
a little older they go to the bottom and
use abandoned sea snail shells for
protection then within the first year of
their life they go to land and lose the
ability to breathe underwater if you
find a coconut crab do not throw it into
the water just give it a good claw shake
and send it on its way I'm kidding do
not touch their claws they will continue
growing for decades we're still not sure
when they reach their maximum size but
it's believed to be at least forty years
of age with some scientists claiming
that they could grow until they're about
a hundred and twenty years old
like all crustaceans coconut crabs molt
as they grow they need to shed their old
exoskeleton and grow a new larger one
the new exoskeleton is initially very
soft which makes them very vulnerable
for a few weeks after molting these
pinchy boys molt every year to avoid
harm they dig a burrow just shed their
old exoskeleton then they eat it to
recoup nutrients and wait for the new
one to harden I guess they really hate
birthdays unfortunately it's getting
increasingly hard to find huge coconut
crabs they got this big because they had
no natural predators on their islands
but humans and the animals they bring
such as dogs and pigs have caused a
rapid decline in their populations
they're now extinct and part of their
historical range such as Madagascar and
mainland Australia hopefully as we learn
more about them we'll be able to protect
them better but until then I guess we'll
have to keep letting them eat kittens
and birds as their populations recover
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you may have noticed that I'm wearing
something new this week you just have to
look closer this is the brand new Animal
Logic watch made in collaboration with
undone watches I never dreamed that my
drawings would become such a large part
of my work but having them come to life
on this channel has been an absolute
dream come true the team at undone
watches are huge fans of this show and
they wanted to partner with us to create
a custom watch using my artwork
obviously I said yes I mean just look at
it it's incredible and now we'd like to
share them with you by clicking the link
in the description you can enter for a
chance to win one of these two beautiful
watches this one is the undone kill II
which has my drawing of a cat eye on the
case back of this vintage chronograph
inspired watch the second one is the
undone Navi and it features a bearded
dragon which is one of my favourite
lizards now I'll have my drawings with
me wherever I go and you can too
it doesn't hurt to be the classiest
scientific illustrator in the room
either so what should we talk about next
please let me know in the comments and
be sure to subscribe for new episodes of
Animal Logic every week thanks for
watching see ya
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