The biggest chameleon in the world, Parson's chameleon, lives in Madagascar's rainforests. It is about the length of a school ruler with its tail straight out behind. The smallest, the leaf chameleon, would sit comfortably on the end of your little finger.
Lots of people think chameleons change colour to hide. They sometimes do - but most colour changes are about how they feel. A relaxed chameleon is greenish-brown. An angry or excited one might flash bright reds, blues and yellows like a traffic light. It is more like a mood ring than camouflage.
A chameleon's tongue is a wonderful piece of natural engineering. It is sticky on the end and twice as long as the chameleon's body. When a tasty insect lands within range, the tongue shoots out faster than your eyes can follow and snaps back with the bug attached. The whole thing takes about a hundredth of a second.
Their eyes are perhaps the strangest of all. Each eye can move on its own, so a chameleon can look forward with one eye and backward with the other at the same time. It is like having two cameras filming in different directions. When the chameleon spots something interesting, both eyes lock onto it together.