What is a Water Bear?

What is a water bear?  Have you got one on your roof or in your garden.  The answer is undoubtedly yes you have, not just one but probably millions!

An Extremophile on your Roof!

Do you know of an animal than can withstand temperatures of -200 °C?  Perhaps you know of one than can tolerate heat of 151 °C?  How about an animal that can live in the vacuum of space for days?  Or even withstand six times the pressure of water at the deepest point in the ocean, the Mariana trench?  What about surviving doses of radiation over 1,000 times the lethal dose for humans?  Well, there is such an animal and there are probably thousands of them within metres of where you are right now!!

Have you got moss?

If you’re at home and you have moss on your roof or in your gutter, there’s a good chance that there are little Tardigrades living in it.  Tardigrades, commonly known as water bears or moss piglets are tiny segmented animals with eight stumpy legs.  They need moisture to be able to move around.  If the environment is too dry for them they will go into a desiccated state and remain that way until conditions become wet enough for them to move around again.  While in this state, their metabolism is lowered to 0.01% of their hydrated state with their moisture content dropping to just 1% of normal.  When they are in this dehydrated form they are known as a “tun”.

They are everywhere!

Tardigrades can be found throughout the world from the poles to the equator and the highest mountains to the deepest seas.  They were named and described by Johann August Ephraim Goeze  way back in 1773.  He called them “little water bear” because of the way they amble along with a similar gait to a bear.  An adult can reach a body length of 1.5 mm with the smallest being under 0.1 mm and the young being as tiny as 0.05 mm.  Over 1,000 species have been described throughout the world.

What do they like?

A tardigrade’s favourite habitat would be on lichens and mosses, in soil and sand dunes, they can be found in marine and freshwater sediments in large numbers.  They have been reported by scientists to have been found in hot springs, under solid ice, in ocean sediments and on top of the Himalayas.  These amazing little creatures are able to survive the most extreme environments that would destroy almost any other animal.  Temperatures close to absolute zero and as high as 151 °C, radiation levels 1,000 times more than tolerated by other animals and surviving decades without water, not to mention being returned alive after being exposed to the vacuum of space for 10 days!!  What an incredible little extremophile the tardigrade is.

Find your own!

So how about finding some and having a look at them under a microscope.  Those of you who have such an instrument, it doesn’t have to be an expensive one, can take a piece of moss from the roof or the gutter or off the ground and soak it for 24 hours in some spring water, not tap water.  Now take a good look at your moss sample under the microscope and see if you can spot one.  You could even try and see them through a x15 hand lens but they will be small, so look carefully.