Meet the Walnut Sphinx Caterpillar. This little guy has a pretty cool defense mechanism that keeps him safe in nature. By mimicking the cries of small birds, squirrels and mice, this little guy is able to ward of larger predators.
Caterpillar species possess a range of anti-predator defenses, from regurgitation to sonar jamming. The North American walnut sphinx caterpillar (Amorpha juglandis) produces a variety of whistling noises when pinched. Limited observations indicate that this causes avian predators to retreat, leaving the caterpillar alone. However, it is unknown why this whistle is such an effective deterrent.