The Year in Science: Animals 1997

When the tiny poison frogs of the Amazon are born, they are harmless. Only mature frogs secrete a protective coating of deadly toxins—so deadly, in the case of one species, that a single inch-long amphibian has enough poison on its skin to kill a hundred people. How do the frogs produce such toxic stuff? This past year herpetologist Janalee Caldwell of the University of Oklahoma in Norman found the answer: they eat lots of ants. Caldwell examined the stomach contents of nine species of frog from Central and South America (Imagine looking into a stomach the size of a speck, she says) and found 135 species of ant, which contained 15 to 20 different toxic alkaloids. In fact, 70 percent of the diets of the most deadly frogs, such as Dendrobates auratus (left) consists of ants. Other, less toxic frogs, like the Ecuador poison frog above, eat less noxious insects