We use our sense of smell for all sorts of things, like locating food and habitat, avoiding danger, and so on. Fish do as well. But instead of smelling scent molecules in the air like humans do, fish use their nostrils to sense chemicals suspended in water.
Virtually everyone listening to this radio segment has relied on antibiotics to treat a bacterial infection. Since the 1940’s, we’ve used antibiotics to combat everything from strep throat to sinus infections. They also play an important role in surgery and cancer therapies.