One very weird critter: Tardigrade
in Moss
Is this an alien?
Probably not, but of all the animals on Earth, the tardigrade might be the
best candidate. That's because tardigrades are
known to be able to go for decades without food or water, to survive
temperatures from near absolute
zero to well above the boiling point of water, to survive pressures from
near zero to well above that on ocean floors,
and to survive direct exposure to dangerous radiations.
The far-ranging
survivability of these extremophiles was tested in 2011 outside an
orbiting space shuttle. Tardigrades are so
durable partly because they can repair their own DNA and reduce their
body water content to a few percent.
Some of these miniature
water-bears almost became extraterrestrials recently when they
were launched toward to the Martian moon Phobos on board the
Russian mission Fobos-Grunt,
but stayed terrestrial when a rocket failed and the capsule remained in Earth
orbit.
Tardigrades are
more common than humans across most of the Earth. Pictured
below in a color-enhanced electron micrograph,
a millimeter-long tardigrade crawls on moss.
