Snake-mimic caterpillar (Hemeroplanes triptolemus)

The caterpillar of a hawk moth, Hemeroplanes triptolemus, hanging from a twig in the Peruvian Amazon. At rest it looks like any other caterpillar. Disturbed, it lets go with its front end, flips over and swells its forward segments into a wedge-shaped head with two big glossy eyespots, a convincing small viper hanging out of the foliage. The eyes even carry pale spots that read as reflected light. A bird hunting caterpillars is suddenly facing what looks like a snake, and that hesitation is all the caterpillar needs.