According to the Integrated Taxonomic Information System (ITIS), there are 171 different species of chameleons.

Chameleons have been around a long time. The Akkadians--an ancient culture that dominated modern-day Iraq over 4,000 years ago--called them nes qaqqari, literally "lion of the ground." This usage was picked up by subsequent civilizations--first the Greek "khamaileon," then the Latin "chamaeleon," and finally the modern English "chameleon," meaning "ground lion."

On average, a chameleon's tongue is roughly twice the length of its body. In a human, that would equal a tongue about 10 to 12 feet (3 to 4 meters) long.

Contrary to popular belief, a chameleon changing its skin color doesn't necessarily mean the lizard is trying to camouflage itself. More often, this remarkable ability is used as a way of controlling body temperature--lightening skin to reflect light and cool down or darkening skin to absorb light and warm up. Another primary function of color change is social signaling: altering skin tone to communicate intentions to potential mates or rivals.

Unlike other animals that change color, such as the squid and octopus, chameleons do not modify their hues by accumulating or dispersing pigments within their skin cells. Chameleon skin has a superficial layer which contains pigments, and under this layer are cells with nano-crystals. Chameleons change color by changing the space between these nano-crystals, which changes the wavelength of light reflected off the crystals which changes the color of the skin.

Chameleons generally eat insects such as locusts, mantids, grasshoppers, stick insects, and crickets. Some larger chameleons also eat small birds and other lizards.

Chameleon saliva has been found to have an average viscosity of 0.4 pascal-seconds, making it about 400 times thicker than human saliva. This sticky spit helps the chameleon capture prey weighing up to 30% of its body weight using only its tongue.

Chameleons have the most distinctive eyes of any reptile. Each eye can pivot and focus independently, allowing the chameleon to observe two different objects simultaneously. This gives them a full 360-degree arc of vision around their bodies.

A chameleon's tongues can go from 0 to 60 miles per hour in a hundredth of a second, about 200 times faster than the fastest car. The fastest chameleon tongue belongs to the Rosette-nosed Pygmy Chameleon, which can shoot its tongue more than twice the length of its body at about 8,500 feet per second (5,795 mph).

Nearly half of all chameleon species today live on Madagascar, including both typical chameleons (Chamaeleoninae) and dwarf chameleons (Brookesiinae), with many species being unique to the island.