The Indestructible Creature From Outer Space

The last blog entry brought the immortal jellyfish to your attention. I had mentioned that even though the animal is biologically immortal, it was susceptible to predators, accidents, or disease. How unfortunate for the jellyfish if it were to be granted eternal life only to be hit by a bus the very next day. So this leads to the logical next question: What animal is the most indestructible? Is there an animal that is susceptible to dying of old age, but can survive conditions that would be the demise of every other life form we know? You already know that I'm going to say that there is such an animal, because I know that you read the title of this blog entry and because if there were no such animal, I would not have a blog entry simple to tell you that.

Tardigrades

Tardigrades are invertebrates that are up to about half an inch long. All of the hundreds of species have four pairs of legs that end in tiny claws, and lichen is their favorite food. They are found just about everywhere on Earth. When I say "everywhere," I mean everywhere -- the highest mountains, the deepest oceans, polar regions, and equatorial deserts. The reasons why they are so widespread is what make these animals very special.

• They can survive temperatures as low as -273° C (-459° F). Absolute zero, the theoretically coldest temperature possible in the Universe, is -273.15° C (-459.67° F). This means the Tardigrades can survive even as their bodies' molecules themselves are nearly at the point of complete immobility.

• They can survive temperatures as high as +151° C (+303° F). At sea level, water boils at +100° C (+212° F). This means that Tardigrades can survive under conditions where most other animals' blood would have boiled and evaporated.

• They can withstand pressures over 87,000 PSI (pounds per square inch). This is equivalent to 5,900 atmospheres or the pressure that's being exerted about 38 miles under the ocean. Of course, there is no place on Earth that is that deep, so you will have to use your imagination.
  

• They can continue to live in a vacuum (no atmosphere at all).

• They can withstand over 1,000 times the levels of ultraviolet radiation normally found on Earth.

Scientists were so intrigued by the capabilities of these 8-legged creatures that they devised a program called "Tardigrades in Space", or TARDIS. I assure all fans of the Muppets and Doctor Who that I am not making any of this up. As scientists often do, when they realized there exists a unique hardy little creature, they said to themselves, "How can we kill it?" They placed a number of Tardigrade species outside a spacecraft in Earth orbit for 10 days. Most of the animals were returned to Earth alive, certifying them as the only creatures known to be able to live in outer space without any type of protection. Stymied in their murderous intent, the scientists are now devising a hammer that can exert more than 87k PSI. I just made that up.

But, wait; there's more! One way Tardigrades are able to withstand these environmental disasters is its ability to enter a cryptobiosis state. That means it shuts off all life processes until the environment improves to the point of sustaining its life. This cryptobiosis state can continue indefinitely -- some Tardigrades have been revived from sediments that were over 2,000 years old. Some maintain that this ability confers biological immortality on these creatures -- however, the fact that they need to enter a lifeless-like state in order to live forever sounds a bit contradictory.

Scientists do not fully understand the life processes of Tardigrades, and they do not yet understand why the evolution of the animals created defenses for circumstances they were very unlikely ever to encounter. In other words, why were they built to withstand temperatures that are rarely, if ever, found on Earth; or why they are able to shrug off someone hitting them with a hammer, when hammers did not even exist millions of years ago? Some speculate that because they can survive in outer space, perhaps their evolution did not begin on Earth after all. I'd play scary music now, but I do not know how to set that up for this blog.