Chameleon

Chameleons are a group of over one hundred lizard species living in Madagascar, Africa, Asia, and Europe. They are famous for the ability to change color, first noted in the third century b.c.e. by Aristotle. In most cases, chameleons are brown, green, or yellow. Their skins can change to almost any combination of those colors, as well as to pinks, reds, blues, and purples. Chameleon species are mostly arboreal. They inhabit southern Spain, Crete, the Saudi Arabian peninsula, Sri Lanka, India, Madagascar, Pakistan, and most of Africa. North American colorchanging lizards, particularly anoles, arewrongly called chameleons.

Physical Characteristics of Chameleons Chameleon maximum body lengths range from one inch to three feet, depending on species. Like other reptiles, chameleons are cold-blooded, with body temperatures the same as those of their surroundings. A chameleon body is flat from side to side; it both looks smashed out of shape and has dorsal and ventral crests, which provides camouflage by making it resemble a leaf. Chameleon eyes, placed on the sides of their heads, can rotate in a full circle, and rove separately or together. This is thought to be partly because chameleons have short necks that do not turn. It is useful for carnivorous chameleons seeking food (insects, spiders, scorpions, and mammals) and not wishing to be eaten themselves. Using independent eye motion, they may seek to eat an insect seen out of the left eye and use the right eye to check for predators that might eat them. Arboreal chameleons have feet that grasp branches like hands. This is because their feet are zygodactyl, with toes of each foot facing in opposite directions, and can wrap around twigs and branches. This helps them to navigate safely in trees. For the optimum arboreal equilibrium, chameleons have prehensile tails to grip branches. The tails curl into snail-like spirals when not needed. Ground-dwelling chameleons lack the prehensile tails and zygodactyly. Some chameleons have on their heads horns which, spearlike, stick out from spaces between upper lips and eyes. They are used in mating and protecting territory. The heads of most chameleons are flat on top and wide on each side, making it seem that they are wearing helmets. Chameleons move slowly and carefully on tree branches. However, their rapidly moving, body-length tongues quickly shoot out of the mouth to catch prey on sticky, mucus-rich ends, and bring it back before escape is possible. Chameleon color changes are due to skin chromatophorea, which hold pigments and pigment-making components. To change color, chameleons send hormone signals through the blood, changing the identities and thus the colors of chromatophore pigments. Chameleon color changes indicate fear, changes in light intensity and body temperature or other environmental changes, and attempts to blend into surroundings and to attract or deter potential mates.

Life Cycle of Chameleons
Most chameleons are arboreal. Exceptions include pygmy (stumptailed) chameleons, which are small, ground-living, and lack prehensile tails. Male chameleons are territorial. In many cases, male invaders of a territory are fought actively and the battle ends in the death of one male. In some cases, the combat is ritual, though the male who is faced down leaves. Males and females are solitary, coming together only to mate. Most color changes indicate breeding intentions, pregnancy, or, on the part of females, disinterest. Regardless of species, chameleons mate year round. Females can lay fertilized eggs several years after mating because they store sperm and can delay their fertilization. Females lay batches of ten to sixty eggs, in some cases in burrows, in others in trees. In vivaparous species, the young, developed from eggs carried by mothers, are expelled onto tree branches. After laying eggs or depositing their young, females have no further contact with offspring. Young chameleons break out of their eggs via egg teeth, designed for this purpose. The egg teeth later fall out, as they have no other use. Chameleons live for five to ten years, if they reach old age.

Three Representative Chameleon Species
Common chameleons (Chamaeleo chameleon chameleon) inhabit southern Spain, northern Africa, and the Mediterranean coast of the Middle East. Arboreal, they grow to ten-inch body lengths, with ten-inch tails and ten-inch tongues. They eat Image Not Available only insects, and mate in late summer. Females lay batches of twenty to thirty eggs. Flap-necked chameleons (Chamaeleo dilepts dilepts) are named for skin folds near their necks and ears. They are arboreal and inhabit South Africa. They eat insects, spiders, and scorpions, and grow up to about fourteen inches long. These chameleons change color extensively, starting from a mix of brown and yellow. Panther chameleons (Chamaeleo pardalis) of Madagascar are arboreal, grow to twelve inches long, and eat insects. They are aggressive and territorial, named for their ferocity, and fighting between males is to the death. Females lay thirty to fifty eggs. Chameleons are not harmful to humans. They are actually ecologically beneficial, eating many insect pests. Chameleons are also thought desirable pets by many people. However, they are difficult to maintain in captivity.