There is a total of 202 known species of chameleon in the world and incredibly more than half of them are native only to one single place - the island of Madagascar off the east coast of Africa. The rest can be found across the mainland, as well as in the Middle East, the Indian Peninsula and there is even one species indigenous to Portugal and Spain. Although they are a type of lizard, chameleons differ a lot from most of their cousins. The toes on their feet are arranged in two groups, two in one and three in the other, which gives them the ability to grasp branches just like we humans do with our thumbs and fingers. When moving they also use their very long tail for balance, but unlike most other lizards they are unable to break off and regrow it in situations of danger.
Chameleons have very distinct eyes, which can move completely independent from one another. The top and bottom part of their eyelids are joined together and only the pupils are visible. They have an incredible range of motion, being able to move 90 degrees vertically and an amazing 180 degrees horizontally. This allows the chameleon to simultaneously scan and track in opposite directions, until he locates his target. When this happens, the other eye will move and fixate on it as well, giving the lizard depth perception. With both eyes locked on the chameleon then uses his very long and sticky tongue to capture its prey.
But by far its most unique characteristic is the ability to change the color of its skin. Unlike squid and octopus, which modify the amount of pigment with their skin cells, chameleons actually affect the way the sunlight is reflected. This is a skill only adult males have, and it comes from special iridophore cells, filled with tiny nanocrystals, arranged in different shapes and sizes. By changing the distance between the crystals, they change the wavelength of the reflected light. When the skin is in a relaxed state, they are very close to each other, hence they reflect very short wavelengths like blue, but when they get excited the distance increases and the colors turn to yellow, orange or even red. In contrast, females and young males remain dull-colored and have a very reduced layer of these specialized cells. All chameleons possess an additional layer of cells, which are designed to reflect large amounts of infrared sunlight and while they do not play a role in changing the chameleons color, they are very important in reflecting heat and keeping the lizard cool.
Chameleons come in many different colors and sizes. The biggest one, the Oustalet chameleon, can grow up to 60 centimeters. In contrast, young Brookesia micra, the tiniest known species, are only a couple of millimeters long and even full grown they will not exceed 3 centimeters, making them one of the smallest vertebrates on Earth.