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without water a human can only survive
for about 100 hours but there's a
creature so resilient that it can go
without it for decades this one
millimetre animal can survive both the
hottest and coldest environments on
earth and can even withstand high levels
of radiation
this is the tardigrade and it's one of
the toughest creatures on earth even if
it does look more like a chubby
eight-legged gummy bear most organisms
need water to survive water allows
metabolism to occur which is the process
that drives all the biochemical
reactions that take place in cells but
creatures like the tardigrade also known
as the water bear get around this
restriction with a process called an
hydro biases from the Greek meaning life
without water and however extraordinary
tardigrades aren't alone bacteria
single-celled organisms called archaea
plants and even other animals can all
survive drying up for many tardigrades
this requires that they go through
something called a tun state they curl
up into a ball pulling their head and
eight legs inside their body and wait
until water returns it's thought that as
water becomes scarce and tardigrades
enter their tun state they start to
synthesize special molecules which fill
the tardigrade cells to replace lost
water by forming a matrix components of
the cells that are sensitive to dryness
like DNA proteins and membranes get
trapped in this matrix it's thought that
this keeps these molecules locked in
position to stop them from unfolding
breaking apart or fusing together once
the organism is rehydrated the matrix
dissolves leaving behind undamaged
functional cells beyond dryness
tardigrades can also tolerate other
extreme stresses being frozen heated up
past the boiling point of water high
levels of radiation and even the vacuum
of outer space this has led to some
aronia
speculation that tardigrades are
extraterrestrial beings
while that's fun to think about
scientific evidence places their origin
firmly on earth where they've evolved
over time in fact this earthly evolution
has given rise to over 1100 known
species of tardigrades and there are
probably many others yet to be
discovered
and because tardigrades are so Hardy
they exist just about everywhere they
live on every continent including
Antarctica and there in diverse biomes
including deserts ice sheets the sea
fresh water rain forests and the highest
mountain peaks but you can find
tardigrades in the most ordinary places
- like moss or lichen found in yards
parks and forests all you need to find
them is a little patience and a
microscope scientists are now trying to
find out whether tardigrades use the ton
state their anti drying technique to
survive other stresses if we can
understand how they and other creatures
stabilise their sensitive biological
molecules
perhaps we could apply this knowledge to
help us stabilize vaccines or to develop
stress tolerant crops that can cope with
Earth's changing climate and by studying
how tardigrades survive prolonged
exposure to the vacuum of outer space
scientists can generate clues about the
environmental limits of life and how to
safeguard astronauts in the process
tardigrades could even help us answer a
critical question could life survive on
planets much less hospitable than our
own
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