text: why are sharks teeth white? and not yellow. i mean they dont brush them. tooth enamel is naturally white.  animals that have discolored teeth get that way because of the things they eat.  generally animals with permanent teeth (mammals) that eat vegetable matter will have the most discolored teeth due to the tannins (same substances that make coffee and tea stain human teeth) in plants.  as there is nothing in flesh to stain teeth (blood doesn't stain enamel) carnivores tend to have whiter teeth.    but with sharks (and other animals that constantly shed their teeth) the teeth never have the chance to get stained as they are replaced so often.