The Invincible Tardigrade

Water bear, SEM

Tardigrades (Phylum: Tardigrada), also known as water bears, were first discovered by the German zoologist, Johann August Ephraim in 1773.  They are water-dwelling micro-animals with eight legs and can reach a maximum size of 1.5mm. Now over 1000 individual species of tardigrades have been discovered to this day.

Tardigrades are some of the most resilient animals known and can be found in almost every environment, ranging from tropical rainforests to Antarctica, and even your own backyard! It is said that these tardigrades get to all these different places by being carried by wind and water currents and then deposited somewhere far away. If you have a microscope, it is actually possible to find your own wild tardigrades!


These water bears are renowned for their ability to survive extreme environmental stresses that would kill almost any other animal, such as being dehydrated, exposed to excessive amounts of gamma radiation and coping with pressures as high as 600 mega-pascals (MPa) – pressures that are beyond anything they might encounter in nature. They can also tolerate being frozen to -272.8 °C (which is just above absolute zero), as well as being heated to 151°C for 15 minutes and still bounce back to life. Not to mention, they can healthily reproduce in outer space! If you were to go into outer space without protection, you will die in only a matter of 15 seconds. The low pressure would force the air out of your lungs and the fluids in your body will expand, causing you inflate. Your capillaries would rupture and the ionising radiation would destroy the DNA in your cells.

So, the question is, how are tardigrades able to survive in these extreme conditions?

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