Small Talk - about the tinyness of tardigrades

a) Length factor 1/3   >>>   volume factor 1/27

Just for warming up a little we will begin with modest tinyness and then pass on the real tinyness - the tinyness of the tardigrades!

The big bottle on the right-hand side of the image is a normal 0.33 liters Coca Cola® bottle. Most of our readers should have come across it at some point, maybe even emptied a few of them.
The tiny bottle on the left side is a collectible, a Coca Cola miniature bottle - just downsized by a modest factor of three.

From this example we learn that a simple downsizing by three will have noticeable consequences with respect to length and at the same time dramatic consequences with respect to volume (factor 27!). This 3x3x3 downsized volume will not event be sufficient for gargling!

b) Length factor 1/10,000   >>>   volume factor 1/1,000,000,000,000

After having sensed modest downsizing we will have a look at the size and volume relations of man and tardigrade:

Everyone of us tends to be fascinated by big animals. E.g. a 35 m whale has the 20fold body length of a man. Thus man is not so far away from the "large end" on the body size scale of organisms.

In contrary the distance from man to minature organisms is much more pronounced. Several times we stated that tardigrades are smaller than Homo sapiens by a factor of 1,000 - and we've received no complaints. But actually this value of 1,000 is wrong. Let's have a closer look: A man might have a body size of 1.70 m. This is eqal to 1,700 mm. In contrast an adult tardigrade might have a body size of 0.17 mm. When dividing the body size of man (1,700 mm) by the body size of the tardigrade (0.17 mm) we will note that the length relation between man and tardigrade is even 10,000 : 1 ! A factor of 1,000 would have already been astonishing but a factor of 10,000 is a real miracle. In spite of its tiny size a tardigrade is able to see, to smell, to run, to crawl and to kiss.

When thinking back to our first factor 3 experiment most of us will admit that a size factor of 10,000 is already well beyond our everyday imagination capacity. So we might go one step back and have a look at one of those 10fold toy magnifiers (as shown below in order to exemplify the downsizing factor of 10,000).

Toy loupes with a respectable 10 fold magnification ... each ca. 2 cm in length.

If we were using those 10fold loupes in order to upsize a tardigrade to man, we would have to use it once, then use it a second time on the result ... and apply it even a third time and a fourth time in order to reach the 10,000 magnification factor.

Other imagination helpers might be:
(1) If we were going to magnify a man by a factor of 10,000 Mount Everest would look like a modest sand heap beside him
(2) For crossing the British Channel (30 km) this man wouldn't need a boat - he might simply jump across it!

But we have not finished yet. The situation becomes really crazy when we look at volume relations. A 1:10,000 body length relation implies a 1:(10,000 x 10,000 x 10,000) body volume relation which of course, is well beyond any human imagination. A consequence of this tremendous tinyness is an extremely low body weight (ca. 1 billionth part of man's body weight). But still there is everything entailed: sharp claws, muscles, nerves, brain and so on.

Besides, tinyness is a perfect survival strategy: many impressive animals have been hunted and exterminated by man, but most of the tardigrades will never be perceived by human hunters. This is real nano.

Well, in any case we shouldn't forget our actual topic, the tadigrades, how they look like and how they move along. Here is a small video reminder for you (file size ca. 2 MB):

Have a nice summer and see you soon!

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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