Chameleons

Most chameleons are green, yellow, or brown colored. However, these animals are famous for their ability to rapidly change the color and pattern of their skin pigmentation among these colors, and almost black or white shades can be achieved. This is done by varying the amount of pigment displayed by specialized cells in the skin, known as chromatophores. This visual behavior is primarily performed in response to changes in temperature, sunlight, and mood, especially when a chameleon is interacting socially with other chameleons. Chameleons may change the color of their skin to blend in better with their surroundings, as a type of opportunistic camouflaging. Although it is often believed that camouflage is the most common reason for the color changes of chameleons, the primary reasons are actually related to the mood or motivation of the animal.

Almost all chameleons are arboreal animals, moving slowly and deliberately in their habitat of trees and shrubs. The often imperceptible movements of these animals, coupled with their usual green or mottled color, makes chameleons difficult to detect among the foliage of their habitat. Chameleons have feet that grip twigs and branches well, with their toes fused in groups of two or three (a zygodactylous arrangement) that oppose each other to confer a strong grip.

The prehensile tail of most chameleons can be wrapped around twigs and other structures to give the animal stability while it is resting or moving around. In some respects, the tail serves as a fifth "leg" for these animals, because it is so useful for locomotion and securing their grip. The laterally compressed body of chameleons also appears to be an adaptation to a life in the trees, by conferring advantages related to the distribution of body weight, and perhaps in camouflage.

Chameleons have very unusual eyes, which extend rather far from the sides of the head within turret- or cone-like, fused eyelids. The eyes of chameleons can move and focus independently of each other. However, chameleons also have excellent binocular vision, which is necessary for sensing the distance of prey from the animal, so that it can be accurately snared by the long, unfurled tongue.

The tongue of chameleons is very important for the method of feeding. The tongue of chameleons is very long, and it can be rapidly extended by inflating it with blood. The tongue is accurately and quickly extruded from the mouth to catch prey up to a body length away from the animal. The sticky, club-like tip of the tongue snares the arthropod prey securely. Chameleons commonly feed on insects of all sorts, as well as on spiders, and scorpions.

Like other lizards, chameleons also use their tongue as a sense organ. The tongue is especially useful as a chemosensory organ which detects chemical signals from the air, ground, or food. The chemicals are transported to a sensory organ on the roof of the mouth, which analyzes the chemical signature.

Male chameleons aggressively defend a breeding territory, interacting with other males through drawn-out, ritualized displays. Some species have horn- and crest-like projections from their forehead which are used by the males as visual displays during their territorial disputes, and for jousting, during which the animals push at each other with their horns, until one combatant loses its grip on the branch, and falls to the ground. Most species of chameleons lay eggs, but a few are ovoviviparous, meaning the eggs are retained within the body of the female, where they hatch, so that the young are born as miniature replicas of the adults.

Some populations of chameleons consist entirely or mostly of female animals. This is an unusual trait in animal populations, and it may be indicative of parthenogenesis in these chameleon species, that is, the production of fertile eggs by females that have not mated with a male animal.