BEARS LOOK LIKE THEY WOULD MAKE NEAT PETS
first water bear I ever saw came lumbering through the water, pushing
over a pile of floating debris. It grabbed another piece of rubble with
a front leg and moved it aside like it was a sofa cushion.
knew it was in control of the scene when it came face to face with a
paramecium, which used all of its cilia to get out of the way. I was
looking through a microscope in biology class observing one of natures
most remarkable creatures. At the time, I did not know how special a
water bear, or to use its proper name tardigrade, was. Scientific
research years later has revealed how extraordinary tardigrades are.
belong to the most radiation tolerant animals on Earth, says a
scientific paper by Jonsson K. Ingemar (Kristianstad University, Sweden)
and colleagues from the University of Copenhagen, Denmark. They are
distinctive in being the only animals known to have survived the
combined exposure to cosmic radiation, UV radiation and vacuum under
real space conditions.
are based in part on the survival of tardigrades placed on the outside
of an unpiloted Russian spacecraft. In the experiment, conducted in
collaboration with NASA, more than two-thirds of the tardigrades survived
the trek, enduring environmental conditions far harsher than any on
are chubby microscopic organisms, the largest ones approaching the size
of a grain of rice. They have eight legs with disk-like claws at the
end and a cute nose resembling a piglets snout. If these charming
little denizens of terrestrial, freshwater and marine habitats worldwide
were a familiar mammal like real bears, the toy industry would be awash
in stuffed water bears. Every child (and some adults) would want one.
writer William Herkewitz reported in Popular Mechanics on the
near-invulnerable nature of these fascinating animals. He noted that
tardigrades have survived heat of more than 300 degrees Fahrenheit and
cold as low as -458°F.
measure of the resilience of these remarkable organisms, Fumihisa Ono
(Okayama University of Science, Japan) and colleagues reported tardigrades
surviving incredibly high pressures more than a million pounds
per square inch. The investigators stated that it was really surprising
that living organisms can survive after exposure to such a high pressure.
are versatile and ubiquitous as seen by their presence on all continents
and habitats from arid deserts to frozen tundra, from mountain tops
to deepest oceans. No other animals have been found to tolerate the
extremes a tardigrade can endure.
the scientific explanation for such incomparable endurance? An ability
to dehydrate so that only a small percentage of their body retains water
has been proposed as one survival mechanism. Another is that they can
lower their metabolism to the point that it is barely measurable.
such a physiological state, a tardigrade can go for years, perhaps decades,
without its basic food of algae or bacteria and without any water. Why
that would also allow it to survive phenomenally high atmospheric pressure
in a laboratory, a vacuum in outer space or high levels of radiation
is not clear.
of different species of tardigrades are known to exist, and only a few
of them have been examined thoroughly enough to know what other special
capabilities they have. The potential for research on tardigrade behavior
is intriguing. Water bears have much to tell us about life and the myriad
ways it can be lived. They may even show us how to survive an interplanetary
is something we should continue to support in our ongoing efforts to
unveil the mysteries of outer space. But let us not forget that intrigue
and mystery are also to be found here on our home planet. Information
lies beneath our feet, waiting to be revealed through research on the
millions of species like tardigrades that we know too little about.
you have an environmental question or comment, email