In a highly informative but slightly ominous animated essay, the ever-philosophical design house Kurzgesagt explains the rampant existence of profoundly deadly bacteriophage (phage) and why these creatures are so beneficial to protecting life on earth.
Phages are very very specialized killers of bacteria. So specialized in fact that humans are
completely immune to them – we are too different. We encounter billions of phages every day and we just politely ignore each other. … if we use phages to kill bacteria, won’t bacteria develop ways of defending themselves? Well, it’s more complex that that, phages evolve too. There has been an arms race between them and bacteria for billions of years and so far they’re doing great.