The toughest animal on the planet

Most creatures require a specific set of conditions to survive: a certain amount of oxygen, temperature, pressure, food, etc.  However, some animals can live in conditions so extreme they kill almost everything else.  These animals are called, fittingly, extremophiles.  One extremophile is the tardigrade, more commonly called water bears or moss piglets.

In general, tardigrades hang around on moss, sucking up water.  However, for some reason, they are able to withstand almost unimaginable conditions.   Temperature-wise, they have survived temperatures of over 304° F (151° C) and down to -423° F (-253° C).  Tardigrades can also survive at extreme pressures.  Some species can survive at pressures 6,000 times that of atmospheric pressure, almost six times the water pressure at the bottom of the Mariana Trench.  Tardigrades have also been shown to survive radiation doses of over 500 times what would kill a human.  The tardigrades accomplish these incredible feats by entering a state of cryptobiosis.  In doing so, they will curl up and dehydrate themselves.  Tardigrades have been known to survive up to ten years in this state.  We don’t know why tardigrades can live in conditions so extreme they aren’t found on Earth, but we are trying to understand them.

Now, as astronomy students, you would probably guess that the most hostile environment in the universe is outer space.  With temperatures of a few degrees above absolute zero and an almost complete vacuum, it seems impossible that anything could survive.  However (as you might have guessed), tardigrades are able to survive in outer space.  In 2007, NASA let a bunch of tardigrades out into the vacuum of space where they were exposed to incredible amounts of solar radiation.  Ten days later they let the tardigrades back in, and when they brought them to Earth, the tardigrades were fine, and some even laid eggs that became perfectly normal baby tardigrades.  This experiment has been repeated multiple times, with the ESA also sending tardigrades into space in a mission they called Tardigrades in Space.  You’re probably thinking the ESA does a terrible job naming things until you learn they shortened the mission name to TARDIS.

So, besides being awesome, why is this information useful? Well, it helps us understand how life might spread throughout the galaxy.  If some tardigrades were ejected from Earth (by, say, a meteorite impact), and somehow they managed to land on another planet, they could bring life to that planet, assuming the planet could sustain life.  This youtube video also does a good job explaining why tardigrades are so awesome.

Sources: 1, 2

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3 thoughts on “The toughest animal on the planet

  1. a2megal says:

    I was actually just reading about your post on Europa where you talked about the possibility of life on Europa. It got me thinking about different types of life in the Solar System and what they may look like. And then I found this post. I am really excited about this information on how tardigrades can survive in space. It amazes me that they are able to stand extreme temperatures, pressures, and doses of radiation. The 2007 NASA mission causes me to think about how this life could evolve on another world. If there was a way for us to place tardigrades on another world in our solar system, could we potentially see the evolution (over many years) of a new species. This species would, I suspect, adapt to this other world, and I wonder if the resulting species would look like life as we know it at all. Thanks for the post!

  2. Megan C says:

    I’ve never heard of tardigrades before, but their ability to survive in extreme conditions not found on Earth is crazy. It doesn’t seem to make sense really, since we normally think of species evolving the way they do to survive the conditions where we live. Maybe they came from another world or developed when the Earth was experiencing different conditions? Love the mission name, and I’m really glad you brought up the possibility of tardigrades being spread elsewhere in the solar system. I feel like most of the time we only think about life getting brought to Earth and don’t spend much attention thinking about how life could spread from Earth. Thanks for posting!

  3. ndtidol says:

    This was a very entertaining post! Despite being a bio major, I’ve never heard of tardigrades before. I’m not sure if I can take this organism seriously after seeing the picture. The resilience of this organism is quite amazing. It’s mere existence challenges the theory of the origin of life on Earth and the “primordial soup” that was rich with amino acids and other building blocks essential to life. The fact that they can withstand such extreme conditions means that they can survive the transitions between worlds. Not to mention that if tardigrades can survive in space, then even worlds that do not seem conducive to life might be able to sustain organisms similar to tardigrades.

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