Caterpillar, El Morro National Monument, 2015.

Scientists have discovered that some caterpillars can whistle! How? You see, insects breathe through spiracles (i.e., the holes in their sides that you see in this photo). After some experimentation, it has been discovered that the caterpillar uses its spiracles to whistle, thereby startling a predator who thought the caterpillar would be easy prey.