Life at low Reynolds Number Re-visited: The apparent activation energy of viscous flow in sea water

In a 1976 lecture entitled “Life at low Reynolds Number,” Edward Purcell examined constraints on mobility of small aquatic animals defining the energetic challenge as “to move far enough to beat diffusion.” We show that essential requirement is need do sufficient work overcome activation energy viscous flow. Raman spectroscopy shows sea water dominated (78–85%) by hydrogen bonded forms, primarily large (H2O)5 tetrahedral pentamer form. Two bonds must be broken disrupt this structure. The strength bond in ~8.4 kJ/mol and experimentally determined flow (~16.7 kJ/mol) approximately equal required break two water. For occur molecular vacancy form for flowing molecule into; smaller needed less required. heat created animal swimming breaks thus forming layer non-hydrogen H2O molecules around animal. These “lubricate” surface yielding more efficient decreases with pressure most likely due weaker under – lab field data support observation. dissipation tidal heat, often attributed “intermolecular forces,” directly related breaking bonds.