Chameleons

Types of animal science: Anatomy, classification, reproduction Fields of study: Anatomy, zoology

Chameleons, the family Chamaeleontidae, have long, sticky tongues to capture prey. Other unique characteristics include eyes that operate independently of each other, leaflike body shapes, ability to change skin color, zygodactyly, and prehensile tails.

Principal Terms arboreal: dwelling in trees chromatophore: a color-causing cell cold-blooded: animals whose body temperatures equal the temperature of their surroundings PREHEnsiLE: able to grip things zygODACTyLy: having toes pointing forward and backward in the same foot

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 color-changing lizards, particularly anoles, are wrongly 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.

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