Zebras are not the only (23)____ that use camouflage. A white polar bear blends in with the snow, while animals that live in the desert are often yellowish or tan so that they blend in with the desert (24) ____. However, snow, desert, forest, and mountains are not striped. So why do some animals, such as the zebra, have stripes? For years scientists have (25) ____ about the reason for striped animals. Today there are two prevalent theories. The more (26) ____ theory suggests that a striped or spotted animal mimics light filtering through the trees or high grass and thus is camouflaged. Another theory suggests that a black-and-white color scheme is an effective warning device, much like stripes on a railroad crossing gate. Stripes are not (27) ____ on mammals but are also (28) ____ on birds, reptiles, and insects. Stripes on a polecat, a marbled salamander, a pied kingfisher, and a carabid beetle warn predators that the striped creature is dangerous or inedible. A biologist (29) ____ an experiment in which cats and hornets were (30) to taste the flesh of 38 different types of birds. The "least edible" rating was (31) ____, to the only three birds that were black and white. Although scientists still do not completely agree on why some animals are striped, one fact they all agree on: a zebra is a(n) (32) ____ beautiful animal."