Frogs learn to recognise the smell of their enemies while they are still developing as embryos, say scientists. Researchers in the US and Canada found that woodfrog embryos were able to learn the "level of threat" posed by their future predators - salamanders. Embryos put into water containing the odour of a salamander and the odour of injured tadpoles learned that the predator's smell was a threat. And the stronger the odour, the more dramatic the tadpoles' reaction.
embryo frog smell predator