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Why would an animal want to look like a leaf or a twig?
To stay alive! Birds, lizards, monkeys, and even snakes are always on the lookout for a tasty six-legged snack. So insects that look like the things around them have a better chance of survival.
Some insects avoid being eaten by using camouflage or mimicry. A camouflaged insect matches its background. That makes it hard for a predator to see it. Mimicking insects copy other animals, usually dangerous ones. They might imitate shape, coloring, sound, and even movement. So most predators get scared and stay away.