MINI MOUTHS

In 1935, Australian scientists came up with an exciting new method to control problematic crop pests. They decided to introduce cane toads from the Americas. The cane toads soon roamed away from their original introduction site, and now inhabit much of eastern Australia. The toads are loaded with deadly poison, making them lethal to many predators that eat them. Yet the toads have had a surprising effect on two species of snake, the green tree snake and the red-bellied black snake. Their jaws, over many generations, have appeared to shrink. Those snakes with smaller jaws eat smaller toads, and therefore ingest less poison.