but if you’re cold-blooded you rely on a
daily dose of sun to warm up your
insides
so reptiles and insects generally fare
better in the cold when they’re small
some species though
just can’t help but defy convention
remember the gargantuan bird eating
cricket of the kalahari
well it has a distant cousin that beats
it hands down in the size stakes
this colossal beast
is the mountain stone wetter
an insect that’s grown as big as a mouse
for one simple reason
wetas evolved back when there were no
native mammals so they took the
ecological niche normally reserved for
small rodents
and matched them for size
being a massive insect is fine when it’s
warm
but this monster species lives high in
new zealand’s southern alps
it had to evolve a way to survive being
big in the cold
by doing something no other insect this
large can
[Music]
even in the shelter of a cave
it can be below freezing
when ice sets in around it
this ingenious hulk of an insect does
something very strange indeed
it freezes itself to death
nearly
this wetter species
actually encourages ice to form in its
body
ice crystals are sharp
if they form inside a cell
they’d tear through the membrane like
razor blades in a balloon
so the key to survival is to ensure ice
only forms outside its cells
first the wetter dehydrates the cells
drawing water out
there the combination of water and
special proteins trigger the formation
of ice crystals
in this state of suspended animation a
mountain stone wetter can survive
temperatures as low as -10 degrees
celsius
an extraordinary eighty percent of its
body can be frozen solid
[Music]
when temperatures rise and the ice thaws
a wetter can gradually re-enter the land
of the living
