DARPA turned to Jelle Atema, a College of Arts and Sciences professor of biology at the Boston University Marine Program, who for many years has been researching how marine animals use their sense of smell. Atema proposed that because sharks are expert at tracking odors over very long distances, the key to steering a shark was to follow its nose. With more than a year of DARPA funding, which ended last year, Atema was able to use electrical stimulation of a shark’s brain, mimicking odor, to guide the shark around a large tank.