Being the heaviest organism on the planet (ignoring anything that photosynthesises or any ridiculously big fungi), baring in mind it lives in water, a blue whale is a huge lump of a mammal and probably has the capacity to reach some speed if given a chance and could probably cause great distress to krill populations if it where to waste more energy painting on go faster stripes. What's the fastest a blue whale has ever been recorded? It has probably never felt the need to outrun a predator or to leap on unsuspecting krill, and isn't really built for speed and has never seen the point in chasing after...anything at all...except krill...and maybe to out compete males if it itself is a male. Theoretically how fast could a blue whale swim if it let it's metaphorical hair down?