The North American Sphinx Caterpillar

The North American walnut Sphinx Caterpillar pretends to be a bird. To make the noise, they squeeze themselves shut like an accordion. It sounds exactly like a bird's alarm call saying there is a bird of prey nearby or that get out of here where we're under attack. The other birds will fly off as soon as this caterpillar makes a clear sound. They're doing it to scare the birds away. That's extraordinary on them. But that's how evolution works. Evolution always starts as a coincidence, which then evolves into being a pattern.