All sperm are not the same. Among fruit flies the longer the reproductive tract of the female the longer the sperm. In tiny crustaceans called ostracods, sperm length can range from several hundred micrometers to several millimeters. And here is some trivia for your next cocktail party, sperm in ostracods can even be longer than . . . → Read More: There Is More Than One Way To Impregnate A Squid