Think you’re a survivor? You’ve got nothing on the cane toad, former native of Central and South America, now scourge of Australia. To snuff out their competition for resources, cane toad tadpoles will actually cannibalize nearby cane toad eggs. And all those eggs the tadpoles are too full to gobble up? Well, researchers recently learned that the hardy amphibians have that covered, too: cane toad tadpoles release chemicals into the water that stunt the growth of developing embryos.

Scientists already knew that cane toads communicate with pheromones and use these chemical signals to locate tasty eggs. They also wondered if the pheromones have another, more insidious, purpose. Biologists at the University of Sydney set up a simple experiment to find out. They placed cane toad eggs in 20 containers filled partially with water; in 10 of those containers, they added tadpoles and separated them from the eggs with mesh screens.

The result: five days after hatching, the amphibians that developed with drooling tadpoles next door were 24 percent shorter and weighed 41 percent less than the isolated groups. Moreover, 40 percent fewer exposed tadpoles survived beyond 20 days, ...