- [Narrator] Like David versus Goliath
the littlest thing can achieve the greatest.
Although you've probably never seen a tardigrade,
you've likely been around them,
and they can beat humans hands down in the game of survival.
They're one of the smallest and most resilient animals
known to man.
Can exist for years without food or water,
and are practically indestructible.
Watch and find out why tardigrades
are really out of this world.
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Tardigrades are cute little creatures,
also known colloquially as water bears or moss piglets,
because the vast majority of them
spend their lives inhabiting wet moss.
You guessed it, the green squishy stuff in your backyard
is likely teeming with tardigrades.
In fact, you can find thousands of them
crawling through your garden top soil.
So you can guess they're pretty tiny.
In truth, most are about 0.5 millimeters.
That's 0.02 inches long.
Imagine a pencil.
Most tardigrades can fit right on
the very tip of the pencil.
And to properly see them you need to use a microscope.
Tardigrade means slowly stepping,
which for an eight-legged creature
seems like a good description.
But moss piglet certainly seems an appropriate nickname
for these short and plump critters with their little claws.
But why call them water bears?
Well, some say they walk with a gait
on stubby legs, similar to a bear.
They can swim as well, being found in both fresh
and marine water sediments.
Anywhere in fact that is wet and has a food source.
Tardigrades, depending on the species,
eat decaying plant material.
Algae, fungi, nematodes, protozoans,
and even each other sometimes.
They also get eaten alive themselves
by snails, mites, insect larvae, crustaceans,
and other small arthropods.
Tardigrades have been crawling around our planet
for 500 million years,
are thought to be the most closely related to arthropods,
but don't look or act like any other animals you know.
Although there are male and females,
they can reproduce by parthenogenesis,
which means their embryos don't need to be fertilized
in order to grow.
They can do it all themselves.
But males can also fertilize eggs
once they have been laid by the female.
Sometimes in her molted skin.
You've probably heard that tardigrades
are extreme survival experts,
which means you can find them all over the world.
On the downside, tardigrades usually only live
for no more than a few months
to a few years in optimum conditions.
Which generally means access to food and hydration.
Yet they have an extraordinary super power.
Their bodies can enter a cryptobiotic phase
using a special protein in which they are,
more or less, dead.
But can come back to life
when environmental conditions are more favorable,
using special antioxidants to protect DNA.
In this ball-like tun state,
with retracted legs and head,
they reduce their metabolic activity
to undetectable levels,
stopping all but life's most essential biological processes.
They can maintain this condition of suspended animation
and resist physical and chemical extremes
for multiple years, if not decades.
In this form they can survive desiccation
and freezing environments such as Antarctica,
near absolute zero in fact.
Or temperatures in excess of boiling point.
But that's not all.
They can be found living at great heights,
like the Himalayas,
and great depths at the bottom of the ocean,
can also endure extreme radiation
and even, believe it or not, space.
In fact, it became the first animal
to survive the oxygen-deprived
sub-zero temperatures of space.
Way back in 2007 when the European Space Agency
discovered their ability to survive extreme dehydration,
severe pressure change, and cosmic radiation,
and yet still reproduce,
when the Foton-M3 mission blasted into the cosmos.
What's more astonishing is that they're now
likely scattered over the moon.
On the 11th of April, 2019, the Israeli lunar lander,
Beresheet, crashed onto the surface of the moon.
A landing on the Sea of Serenity
that was anything but tranquil.
But it was more than just the spacecraft that collided.
Thousands of dehydrated tardigrades
were also probably ejected onto the surface
in a protected environmental payload
that may well have survived the impact.
Some question whether the fact
that they can only stay alive in these extreme environments
in their dormant tun state
truly makes them extremeophiles,
because they're not technically living.
Well, if scientists discover a way to rehydrate them
on the lunar surface, astronauts could return to the moon
to settle the argument.
But whatever you think about this,
you have to agree that they're pretty unique creatures
that could help scientists better understand
how humans can survive space exploration.
Because if Earth has to face another cataclysmic event
of the scale that wiped out the dinosaurs,
it will be us searching for new planets to colonize.
Tardigrades will ride out the end of the world.