Many animals use camouflage as a way of making themselves invisible to other animals. Predators use camouflage to blend in with the environment while they lie in wait for unsuspecting prey animals to walk or swim by. More commonly, though, it is the prey, the animals hunted by predators for food, that rely on camouflage as a means of protection. For animals that possess none of their own defenses, like spines, poison, or sharp teeth, remaining hidden provides the best chance for survival.

Usually animals that blend in with their environment are born with all the camouflage they need. The alligator snapping turtle, the horned lizard, and the walking stick, for example, are unable to change their appearance. Their color and shape have evolved to match the general conditions in their area and remain the same for the duration of their lives. Other creatures, however, have the ability to change their appearance depending on the local environment. In some cases, as with the flounder or the octopus, these changes take place internally. In moments, these creatures can change the color and pattern of their skin by changing the color of individual cells in the skin. Other animals change their appearance by donning costumes made of objects they find in their environment. Some species of crab and many different types of aquatic insects use a gluelike substance secreted from their exoskeleton to attach shells and stones to their back.

Physical characteristics, whether they are features an animal is born with or those an animal acquires, are critical to a successful disguise. However, without the proper behavior, the best camouflage may be worthless. Movement can be the hiding animal's enemy. This is why so many animals that use camouflage spend much of their time motionless. Blending in with a background of rocks requires sitting still. Snapping turtles do this very well, remaining almost completely motionless for nearly an hour at a time, while they wait for prey to come to them. Walking sticks and tree snakes don't have that advantage. They must move in search of food. Often, though, their movements mimic the swaying of branches to which they are attached, as much as their physical characteristics mimic the shape of those branches. In this way an animal can remain hidden as much by what it does as how it looks.