Fertilizing the surface waters is not the only thing the whales do. By plunging up and down through the water column, they also keep kicking the plankton back up into the photic zone, giving it more time to reproduce before it sinks into the abyss. Even today, though whale populations have been greatly reduced, the vertical mixing of water caused by movements of animals up and down through the column of the oceans is, astonishingly, roughly the same as the amount of mixing caused by all the world's wind and waves and tides.