Nonato Mendes ignored the leeches squirming underneath his T-shirt. With a deep breath, he plunged his gloved hand into the net that was piled on the deck of the boat, grabbing the electric eel behind its head. Skillfully keeping its writhing body away from him, he avoided the excruciating jolt—eight times stronger than a police-issued taser. It was his 96th capture that year, the last needed for his field research. For more than 20 years, Mendes, a federal environmental agent at Brazil’s Instituto Chico Mendes and a Ph.D. student at…
