Physical characteristics

Chameleon Care Guide

Chameleon Care Guide

Get Instant Access

Chameleons are best known for their ability to change colors. The palette of any species is limited to only certain colors, however. In the case of members of the genera Brookesia and Rhampholeon, the palette consists mainly of shades of tan, brown, and black. The coloration of juvenile chameleons is usually more cryptic than adults of the same species, which may help conceal them from predators. The most dramatic and varying coloration probably belongs to the panther chameleon, Furcifer pardalis, from Madagascar. Within their wide geographic range in the northern third of the island, the coloration of adult males varies significantly from locale to locale, with numerous distinctive color palettes, such as pink and blue, green and red, aqua blue and green, red-orange and white, and turquoise and navy blue.

Chameleons display variations of their color palettes in response to psychological or physiological stimuli and to communicate, not to match their background as was once believed. Although chameleons lack vocal chords, some species are capable of vibration that produces an audible sound or can expel air forcibly from the lungs to generate a hissing or squeaking noise. Chameleons also are known to make sounds in a frequency inaudible to the human ear, but they cannot hear very well, because they lack eardrums and external ear openings.

A male communicating his intentions to a mate often sports the most vivid colors at his disposal. A female likewise will display coloration to communicate her willingness to mate. Calm, subdued colors may indicate receptivity, where dark, intense coloration warns her suitor to stay away. In a few species, such as Calumma boettgeri and C. nasuta, females show striking purplish blue spots, called "threat spots," on the head to deter males. Competing males exhibit bright and intense colors, but the loser usually changes to drab coloration and slinks away to indicate that the contest is over. Chameleons that have a range of colors in their palette may manifest them on different parts of the body, such as the legs, throat, or head. Some are capable of showing stripes and patterns that recede when the chameleon is not in an excited or stressed state. Calm chameleons typically display the least vivid colors. An ill chameleon may become dark or pale in coloration, and sleeping chameleons are often very pale. Color also plays a part in thermoregulation; dark colors absorb the sun's rays when chameleons are cold, and paler colors deflect sunlight.

The epidermis does not grow, and the chameleon sheds completely from time to time as it outgrows this layer of skin. Two cell layers beneath the transparent outer layer can contain red and yellow cells containing pigment granules called

Chameleon Physical Description

A veiled chameleon (Chamaeleo calyptratus calyptratus) uses its ballistic tongue for prey capture. The tongue pad is withdrawn to form a pouch (invaginated) immediately before prey contact. The pouch engulfs the prey and wet adhesion and interlocking muscles maintain grip while suction created by the pouch retractor muscle transfers the prey deeper into the pouch. The tongue retracts until it returns to its resting position on the hyoid bone and the prey is in the chameleon's mouth. (Photo by John H. Tashjian, courtesy of Reptile Haven, Escondido. Reproduced by permission.)

A veiled chameleon (Chamaeleo calyptratus calyptratus) uses its ballistic tongue for prey capture. The tongue pad is withdrawn to form a pouch (invaginated) immediately before prey contact. The pouch engulfs the prey and wet adhesion and interlocking muscles maintain grip while suction created by the pouch retractor muscle transfers the prey deeper into the pouch. The tongue retracts until it returns to its resting position on the hyoid bone and the prey is in the chameleon's mouth. (Photo by John H. Tashjian, courtesy of Reptile Haven, Escondido. Reproduced by permission.)

Sex Determination Chameleons
The tongue anatomy of a chameleon hunting. Top: tongue is in resting position; middle: tongue moves out of mouth; bottom: tongue is fully extended and stuck onto insect. (Illustration by Joseph E. Trumpey)

chromatophores, and, beneath them, there are cell layers that reflect blue and white light. Below these layers are black or brown pigment called melanin. As these layers of cells expand, contract, and overlap due to result of stimulation (or the lack of it), the chameleon can rapidly change color.

Sex determination in adult chameleons is not a difficult matter for most chameleon species, because they most often are sexually dimorphic, meaning males and females are different in form or size. For example, in the majority of species where males have horns, females lack horns. Males are usually larger than females, except in the genera Brookesia and Rham-pholeon. Species that are not sexually dimorphic may be different in coloration, or sexually dichromatic, such as Furcifer pardalis. Females of this species are typically a reddish orange or tan marked with brown or black, regardless of geographic locale. Determining the sex of species in the genera Brookesia and Rhampholeon depends primarily on the presence of a bulge at the base of the tail created by paired sexual organs called hemipenes. It is much more difficult to ascertain the sex of juveniles of most species from birth to about six months of age, or whenever the first indication of adult coloration, horns, crests, or a hemipenial bulge becomes apparent.

The most important physical feature of a chameleon is its large and protruding eyes. A chameleon can move its eyes independently and is able to process two images at once. This ability is the chameleon's best defense against predators,

Hemipenes Humans

Was this article helpful?

0 0

Post a comment