The control of water flow in living organisms is central to their survival.
Amphibians die in long time exposure to salt water raising many biogeographical questions about
how oceanic islands like those in the Gulf of Guinea are home to so many
species of amphibian.  Cholera, such as the outbreak that decimated Haiti
after the earthquake some years ago, similarly is a malady that arises from
uncontrolled water flow induced in the cells of the small intestine
by bacterial toxins.  Even these humble bacteria can themselves die if
quickly placed in a solution with widely different osmotic conditions.  In this
talk I will examine all three of these case studies from a mechanical point of
view, with special emphasis on the mechanosensitive channels in bacterial
membranes that are thought to protect them from osmotic stresses. 
The talk will combine insights from continuum theories of elastic deformations
of cell membranes to single-cell experiments designed to test those theories.