Among the lizards, chameleons are the only ones that can see in two different directions at once. The eyes of a chameleon protrude from his or her head on what looks like tiny turrets. The cone-shaped eyelids swivel with its eyes, exposing only the pupil.
Chameleons have monocular vision, meaning their brains can process the images from both eyes separately. But this by itself, this is not unusual in the animal world; many species, such as deer, have eyes on the sides of their head to see two different images at once.
However, chameleons give a new element to the monocular vision, as the only animals that can move the eyes in different directions while capturing two images at once. When a chameleon sees its prey, it can swivel both eyes forward for instant binocular vision, giving it the spot-on depth perception important to accurately shoot out his tongue to grab its food.