Monday, April 30, 2012


Had to work all night last night, so a quick post today. Figured I'd do a quick technical note.

One of the terms you'll see me use quite often here is 'viscosity'. The formal definition is that viscosity is the resistance of a fluid to changes in rate of shear. In colloquial terms, this means how thick and sticky the fluid feels (high viscosity means 'thicker' fluid). What you might not know is that the effects of viscosity aren't constant across body sizes: little things experience a stickier world. As it turns out, in biology, it is the relative viscosity that matters. For a tiny insect, air feels thick and heavy - the smallest flying insects basically paddle through the air, rather than fly in the normal sense.

I'll be talking more about this soon, but it's a great item to keep in mind as it explains a lot of biology with only a few simple rules.


  1. "in rare of shear"? Should that be rate? Range? Rage?
    Rare seems an odd term...

    1. Yes, that should have said rate. Thanks for the catch! Just fixed it.