Tardigrades: Powers of the “Water Bear”

One of the most incredible creatures on Earth is one so small we can only see it with a microscope.  This tiny animal, called a tardigrade or “water bear”, is only about a millimeter long, and yet it can survive an amazing range of conditions.  Hot, cold, dry, wet, and even the vacuum of space – somehow, the tardigrade can survive them all.

Tardigrades prefer to live in lakes, on moist pieces of moss, or other wet environments.  However, they can survive in extremely dry environments.  In 1995, after 8 years of no water, dried tardigrades were brought back to life.  It turns out when a tardigrade dries out, it retracts its eight legs and its head.  It then sheds almost all the water in its body, slows its metabolism to only 0.01% of the normal rate, and enters a state of suspended animation.  While in this state, a tardigrade is known as a “tun”.  Tardigrades can stay this way for decades and reanimate upon coming into contact with water.  If a tardigrade stays in the tun state for too long, its DNA gets damaged – however, after it awakens, the tardigrade can fix it.

Water bear and tun, SEM
Tardigrade in the tun state

Tardigrades also have the ability to survive a huge range of temperatures.  Testing in labs has revealed that tardigrades can survive being frozen to -272.8 °C (absolute zero is -273.15 °C).  The lowest temperature recorded on Earth was -89.2 °C in Antarctic in 1983.  On the other end of the scale, tardigrades are known to survive at temperatures over 148.9 °C.  The hottest temperature on Earth is about 56 °C.  Not only can tardigrades deal with a variety of temperatures, they can also survive large amounts of radiation.  Tardigrades have been known to survive lethal doses of x-rays, alpha radiation, gamma radiation, and UV radiation.

Finally, tardigrades seem to endure both high pressure and the vacuum of space.  Studies have shown that tardigrades in the tun state can survive pressures of up to 600 MPa (megapascals).  For comparison, the deepest part of the ocean, the Mariana Trench, has a pressure around 100 MPa.  Other studies reveal that tardigrades survived being in a low orbit around Earth, exposed to the vacuum of space and radiation.  It seems this little “water bears” have the power to survive in the most incredible range of environments.

Tardigrade on the move


Tardigrades return from the dead

Facts About Tardigrades

(Featured Image)


4 thoughts on “Tardigrades: Powers of the “Water Bear”

  1. Wow. This is seriously a freaky little organism. While not technically an extremophile, this little dude can survive a long time in places that humans can’t. One time, when I was 9, I spent 3 days living in my back yard in a tent with my dad so he could show me what it was like to live in the wilderness. I had to go back inside on the third day because I had a fever of 101 degrees. Anyways, if I were more like the “water bear”, I would have been able to survive longer. Hopefully we can study these little guys and use our findings to help us survive in strange environments.


  2. I had never heard of tardigrades prior to our last lecture, so this blog post was very informative. Their versatility is amazing; it seems like they could survive almost everywhere in the Solar System. That said, I wonder how they developed. While they can clearly survive outside of Earth’s relatively temperate climate, can something like this develop in a harsher climate? As we learn more about potential life on Enceladus or Europa, it will be interesting to see if tardigrade-like creatures have evolved there.


  3. Tardigrades are very cool! Every time we look at things in a new way with science, we find out so much more about them. From looking at the sky using radio telescopes to using powerful microscopes to detect tiny creatures. Reading your article made me think of another possible solution to the Fermi paradox. (the subject I had written my blog post on) Maybe life is out there in different sizes that we cannot detect. Perhaps technologically advanced beings downsized to a more efficient microscopic body that was less taxing on their resources. Whatever the case, the resilience of the tardigrade serves as evidence that life comes in many shapes and sizes.


  4. The sheer variability of environments in which the Tardigrade can survive makes me feel like it’s impossible that we are the only life in the universe. Based on how easy it is to create amino acids, I can’t imagine that creatures like these haven’t formed in the practically infinite environments that exist. I feel like all it’d take to change the mind of someone who believed the rest of the universe is lifeless is an introduction to the tardigrade!


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