the American Museum of Natural History sense of smell they can’t sense of smell tiny amounts of chemicals на больших расстояниях sharks can smell their prey American Museum of Natural History American Museum of Natural History detectar una gota de sangre en una piscina olímpica tienen la región del cerebro del olfato ampliada shark information site American Museum of Natural History sense of smell don't believe it over long distances American Museum of Natural History 100 to 200 yards