1. The Chameleons' closest relatives are ...the iguanas and dragon lizards (Agamidae). In fact, there are iguanas living in Americas called false chameleons, that resemble a lot the real chameleons of the Old World, and even have the ability of changing their color. The oldest known chameleon is the Mimeosaurus, from the Upper Cretaceous (during the dinosaur times) of Mongolia. It already had a high skull with a marked helmet.
Today, the 156 species of chameleon species are concentrated in Africa, Madagascar and neighboring areas. Just one species reaches southern Europe and another one India.
2. Unlike most other lizards, chameleons do not creep, but walk slowly, moving just one limb at a time. Most are arboreal and have opposable digits, two against three (like in koala). On thick branches, chameleons use their claws for climbing. Most chameleons have a prehensile (grabbing) tail, and can stay on a branch securing with just two feet and the tail. 130 species are tree dwellers. Because of their arboreal life, chameleons do not compete with other lizards.
3. There is a false opinion that the chameleon changes its color to mimic its environment as a defense against predators. An individual able to shift its behavior in accordance with different persons is compared to a chameleon, but this does not happen with the real animal.
In fact, a chameleon attacked by a predator turns reddish with brown or yellow stripes, as most of the chameleons' predators (snakes, mammals) do not distinguish well the colors.
Actually, the chameleon is constantly changing its color according to its emotions, light and temperature. In the cool morning, chameleons warm up at the sun, taking a black
coat that adsorbs easier sun heat, besides flattening their flanks. During the night, the chameleons turn whitish, faded. In strong light, chameleons turn brownish. At 25o C they adopt a green color, while at 10o C, their color turns gray.
If a leaf is put on the back of a chameleon and removed after a period, it will leave a color mark on its back, following its shape, due to the shifts in light and temperature.
As chameleons are somehow related to iguanas, it is plausible that the changing color ability developed in a remote ancestor, during the dinosaur era. Thus, being a chameleon won't hide your real feelings. There are in fact some animals that DO copy their environment, using chromatophores, like octopuses or many flatfishes, like flounders, for approaching prey or avoiding predators.
Chameleons possess in the skin chromatophores (pigment cells) containing melanin (which gives the black color) and various other pigments of different colors, but also fat droplets. Chromatophores retire or display their ramifications, and this way the chameleon controls its color.
The color change is under the control of spine nerves and hormones (adrenaline secreted by the adrenal gland and hormones of the hypophysis). Colors displayed by the chameleons vary from gray to whitish, black, vivid green, green-yellow, olive or blue.
Adding to their natural colors their ability to stay still for minutes and their wagging and extremely slow movements (unusual for a lizard) that makes their laterally flattened bodies, adorned by spikes, horns and protuberances, to look like a leaf or twig shaken by wind, we now understand why they may be inconspicuous for their predators and prey.
4. Chameleon afford their slow movements, due to their hunting technique, based on their tongue, which is the longest in the world compared to the body length, in most species being as long as the body and tail combined. The tongue is launched and put back in a fraction of second (0.04 s the launch (!), 0.5 s the put back). No wonder a chameleon can catch 4 flies in 3 seconds...
The tongue is like a long tube finished in a sticky bulb, due to the mucus secreted by glands located in its tip. The resting tongue is folded like an accordion around a bone called Processus entoglossus. For stretching the tongue during the hunt, the animal must relax longitudinal muscles that act like a spring.
Chameleons hunt mainly insects (including bees and wasps that do not have time to employ their defensive stings because of the velocity of the tongue), spiders and even small birds and rodents in the case of the largest species, than can be 70 cm (two feet) long. This tongue hunting technique is also practiced by some newt species from Americas.
If the prey is located out of the tongue's range, the chameleon approaches slowly and patiently, till the point where it can trigger the tongue weapon efficiently. Chameleons have even teeth used from chopping prey to fights between rivals.
These lizards eat on the morning and evening, avoiding the midday heat. In temperate climate (like southern Spain) they are inactive during the winter.
Chameleons drink dew and rain water, but they can also adsorb water through their skin (like some desert iguanas and dragon lizards do).
5. Another astonishing ability of the chameleons is that of moving the eyes independently, with an angle of 180° horizontally and 90° vertically. This way they can scan larger portions of their environment. Still, when an eye spots a prey, the eyes are moved to look in the same direction forward, for creating the binocular vision necessary for assessing the distance where the prey is. Each eye can form 3-D images , the eyes functioning alternatively and independently one from the other. This way, the chameleon can explore in 3-D its environment without moving its head, so that it does not attract the attention of the targeted prey.
The visual field of an eye is similar to a teleobjective of 100-135 mm. The cornea is just 16 microns tick.
Chameleons lack a tympanum membrane and have poor hearing and extremely poor smelling, their hunting technique being based on sight.
6. Chameleons are solitary and extremely territorial, rejecting even the company of other chameleons. When an intruder enters a chameleon's territory (from a predator to a chameleon of no matter what sex), the animal starts to wag, raise up on its feet, swell its throat and the body (with the help of inner air sacs going from the lungs through the inner organs) looking bigger and more menacing. Jaw clacking, whistling, and … menacing colors add to the show! The defeated one will adopt a pale-gray color and will leave the territory.
The chameleon molts 3-4 times annually. Chameleons are vulnerable when molting and on the ground.
7. Males are larger and more vividly colored than females, and also posses a rostrum (an elongation over the mouth). Females also have smaller horns and helmets (in species which have them). Males intimidate and fight each other for females, biting and hitting head to head with their horns and helmets.
During mating, the male grabs the female by the nap with the jaws, and immobilize her with his limbs and tail.
One month later, the female digs up a nest at 10-20 cm depth into the soil, deposes 6-40 eggs, cover them with soil and abandons the nest. Hatching can occur between 6 months and 2 years. Some chameleon species do not lay eggs, but keep them in the womb till the youngsters hatch.
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