Kratt Brothers — as Chris and Martin Kratt are known — were on the lookout for giant river otters, German shepherd-sized animals also known as “lobos de rio,” or “wolves of the river.” A sudden snorting sound had tipped them off to the presence of the endangered predators feisty enough to chase off jaguars, so they hopped into their little boat, video camera in hand.“We were so into it, and they were just right there,” recounts Martin. “We were getting great stuff.