A theory for the hydrodynamic origin of whale flukeprints

Whale flukeprints are an often observed, but poorly understood, phenomenon. Used by whale researchers to locate whales, flukeprints refer to a strikingly smooth oval-shaped water patch which forms behind a swimming or diving whale on the surface of the ocean and persists up to several minutes. In this paper we provide a description of hydrodynamic theory and related experiments explaining the creation and evolution of these “whale footprints.” The theory explains that the motion of the fluke provides a mechanism for shedding of vortex rings which subsequently creates a breakwater that damps the short wavelength capillary waves. The theory also suggests that the role of natural surfactants are of secondary importance in the early formation of these prints.