Veiled chameleon

The veiled chameleon (Chamaeleo calyptratus) also known as the Yemen chameleon or cone-head chameleon, is a species of chameleon native to the mountain regions of Yemen, the United Arab Emirates, and Saudi Arabia. They are arboreal, living in upper tree regions and mountainous terrain at high altitude. Due to the veiled chameleons' popularity, distinctive appearance and hardy nature, they are often kept as exotic pets around the world, and befittingly they are the most commonly bred and available species of the genus in the reptile pet trade.

Natural habitat
Chamaeleo calyptratus is an arboreal lizard species that ranges from Asir Province, southwestern Saudi Arabia, to Aden, Yemen, where it lives on high, dry plateaus up to 2800 meters, as well as in foothills, forests, low-elevation maize fields, and inland river valleys. They are diurnal, mostly found in vegetation 0.2–3 meters above ground, although they can be found sleeping higher up in branches. They are one of the few species of chameleons which can tolerate wide temperate ranges, though they prefer to live in a temperature range of 75 to 95 degrees F. They have also been introduced into the United States in parts of Florida, Hawaii, and California, and are often kept as pets including in other parts of the world.

They are stimulated by running water, and do not recognize stagnant bodies of water. As such, they are oftentimes found in high-humidity areas, and collect water mostly from morning dew from vegetation, and runoff water below mountaintops. This factor prominently determines a veiled chameleon's choice in habitat and rate of survival in the wild. Their diet other than water is also a factor in their selection of natural habitat, as the mainstay of their diet–insects–are found prominently near dense vegetation. With this, in combination with their arboreal nature, they are often found in tree tops, shrubs, and other similar environments, most of which allow them to lie in wait for prey or hide from predators. This is also attributed to the fact that veiled chameleons have zygodactylous feet and a prehensile tail, allowing them to grasp branches at high altitude.

Appearance
Veiled chameleons bear a physical description typical to many species of chameleon: distinguishable for their crowned head, shape-shifting midsections, zygodactylous feet, separately mobile stereoscopic eyes, their long, rapidly extrudable tongue, swaying gait, and multicolored complexion. They have a prehensile tail with which they often use to grasp objects and/or hang from them. While idle, the tail will curl up in a spiral pattern and unravel for balance while walking. They are a large species of chameleon, with males reaching an overall length of 60 cm (24 in), and females being slightly smaller, reaching a length just under 30 cm (12 in). Average specimen usually grow to between 35–45 cm (14 and 18 in). Their midsections can typically expand and retract to shift between shapes, ranging from an elongated cylindrical shape to a tall but thin "broadcasting" shape. The feet of the veiled chameleon are fused into a group of two and a group of three toes which oppose one another to grasp branches in a pincer or clamp-like arrangement.

Skull casque
Chamaeleo calyptratus is recognizable for its "veil", formed with a dorsal midsagittal crest extended posteriorly to form a skull casque. The basic structure of the veil is the frontal ridge called the parietal bone, with the rear sides being the squamosal bones. Between this bone structure lies the jaw adductor muscles, giving the veiled chameleon a powerful bite relative to its overall size. The males' casque is typically much larger than the females' (pictured right).

Auditory senses
Like snakes, chameleons do not have an outer or a middle ear, so there is neither an ear opening nor an eardrum. However, chameleons are not deaf: they can detect sound frequencies in the range of 200–600 Hz. Chameleons can see in both visible and ultraviolet light.

Eyes
Its eyes are relatively large and capable of independent stereoscopic 360&deg; movement, covered by a thick granular lid with a small pinhole opening for the pupil. Independent movement allows them to rotate and focus their line of sight separately to observe two different objects simultaneously. Prey is located using monocular depth perception, opposed to stereopsis. The amplitude of eye mobility is very large for a vertebrae. This allows a chameleon to watch an approaching object while simultaneously scanning the rest of its environment.

Etymology
The English word "chameleon" (also "chamaeleon") derives from Latin chamaeleō, a borrowing of the Greek χαμαιλέων (khamailéōn), a compound of χαμαί (khamaí) "on the ground" and λέων (léōn) "lion". The Greek word is a calque translating the Akkadian nēš qaqqari, literally 'lion ground' (adjectives follow nouns in Akkadian).

The term "Yemen chameleon" or "Arabian chameleon" derives from the association of natural environment, being indigenous to Yemen and Saudi Arabia. The term "veiled chameleon" or "cone-headed chameleon" refers to its skull casque, a unique identifying factor in the species calyptratus, sometimes also referred to as a "veil" or "cone".

Evolution
In the wild, veiled chameleons occupy the western coast of Yemen and the southwestern coast of Saudi Arabia at altitudes up to 2500 meters. The oldest known chameleon is Anguingosaurus brevicephalus from the Middle Paleocene of Anhui, China. Other chameleons in the fossil record include Chamaeleo caroliquarti (Lower Miocene, Dolnice, Czech Republic and Wintershof-West, Bavaria) and C. intermedius (Upper Miocene, Fort Ternan, Kenya).

Pet trade
Chamaeleo calyptratus has become a very popular specimen in the reptile pet trade, likely due to their hardy and exotic nature, as well as proliferation and aptitude to breed in captive environments. The trend of the importation of wild caught chameleons has declined in recent years. Between 1977 and 2001, 18,068 individuals were exported for the international pet trade. Major sources for these specimens have not been traced historically, though it has been reported that between 1992 and 2001 the majority of captive-bred chameleons in trade were from the Czech and Slovak Republics, and that these countries only export C. calyptratus. For the period 1999-2002, an average of 2,170 live specimens were exported annually from Yemen. Due to veiled chameleon's readiness to breed in captivity, it is thought that the vast majority of this species sold in the pet trade are from captive stock. However, they are traded domestically in Saudi Arabia for the local pet trade, but in very low numbers. The availability of Chamaeleo calyptratus in pet stores is seasonal and depends on region.

Sociology
Veiled chameleons are asocial creatures. The presence of other chameleons or animals increases stress levels in a chameleon, as they are generally solitary creatures. In the wild, a chameleon's habitat is generally large and complex enough to allow for animals to avoid other animals, as well as secluded hiding spots in trees and dense foliage, although while in captivity veiled chameleons require separation from other animals except during the mating process. Chameleons generally tend to give off several warning signals when they notice the presence of another animal, usually in the form of rapid change in color before conflicts occur.

It has been shown that chameleons exposed to ultraviolet light are more socially inclined, however. They become more apt to breed, as it stimulates the pineal gland. Juvenile chameleons are also less territorial, and can therefore be housed together in the same enclosure without competition, though as the veiled chameleon matures, he will be less tolerant of other animals within general proximity to his "territory".

Coloration
Veiled chameleons have a wide diversity of color, though they retain a base color of green, marked with yellow, white, or brown stripes and spots. Depending on the animal's emotional state, this green will range from a pale lime to a red olive drab. When veiled chameleons are stressed, they often display strong coloration, including bright yellow and sometimes even black. Surroundings only partly contribute to a chameleon's change in color, and despite popular belief they are not known to camouflage as a defensive mechanism. Non-breeding females and juvenile chameleons are generally a uniform green color with some white markings. Breeding and gravid females are a very dark green with blue and yellow spots. The prominence of these markings is dependent on several factors, including health, mood, temperature, and location.

Veiled chameleons also change coloration as a sociological function, and will sometimes do so rapidly reflecting behavior while interacting with other chameleons. In some cases, it was found that male veiled chameleons will exhibit a two-stage color warning system which can help avoid physical conflict. "Such displays could help prevent contests between mismatched opponents," says Russell Ligon from Arizona State University; in such cases, the two in conflict will concede a point where one is more dominant over the other and avoid physical distress. Male chameleons will change upon the sight of another male from a neutral to excited, in example, from a drab brown to a bright turquoise with stark yellow stripes. The distinction and contrast in the stripes can predict the likelihood that the male is going to approach the other male. This is considered the first stage in color-based warning, with the second being a rapid change in head coloration from dark to brighter, and the change in body shape from somewhat tubular to a tall, thin oval shape, "broadcasting" the skin's coloration (a behavior exhibited in many other cases as well). Despite the studies and positive results on chameleon's color warning system, it does not always avoid conflict and they will often settle disputes by "pushing and shoving." As another defensive mechanism, veiled chameleons are known to hiss and sway their body back and forth sharply, as if striking.

Females also change color according to emotional state, though not the same as males do. Females primarily change colors based off of levels of stress and during the mating process. Typically a female will bear a lime green color with light colored stripes. While stressed, she can turn very dark, almost black, or very pale, and while breeding or gravid, she can turn dark green with blue and yellow spots.
 * Further reading
 * "Chameleons Communicate with Complex Colour Changes During Contests: Different Body Regions Contain Different Information" at Royal Society Publishing by Russel A. Ligon and Kevin A. McGraw

Purchasing
Purchasing the right veiled chameleon is an important aspect in experiencing successful husbandry. Firstly, ensure the animal is captive-born (meaning it was hatched from a reputable breeder, not captured and imported from a wild environment). Wild-caught chameleons have the potential to be diseased or have some other health concerns, such as high levels of stress, dehydration, parasites, and in some cases nutritional deficiencies which can lead to metabolic bone disease, among others. The only instance where it would be considerable to purchase a wild-caught chameleon is to augment or proliferate the genetic diversity of a large-scale breeding operation. The rate of importation of wild-caught chameleons in the United States and other countries has declined in recent years, therefore accessibility of wild-caught chameleons is growing smaller. Additionally, captive-bred chameleons from reputable breeders (including commercial and career zoologists) are produced annually, making them more popular and accessible. However, importation has become less and less necessary in the United States to obtain wild-caught chameleons due to increasing introduced populations in Florida, California, and Hawaii.


 * You can always ask a pet shop employee about a chameleon you're interested in. If the associate cannot answer your question regarding whether or not it is captive-bred or wild-caught, do not purchase it. Reptile expo vendors commonly sell captive-bred chameleons, so you may also inquire with a seller there as well.

Additionally, there are quite a few health concerns which should be considered before purchasing a veiled chameleon.


 * Before purchasing an animal, ask the vendor, associate, or shop employee for permission to inspect the chameleon. Do not purchase an unhealthy chameleon except with the intent of rescuing the animal (only do so if you are absolutely sure you have the time and the means to properly care for the animal).

A healthy chameleon should:


 * have straight limbs – a veiled chameleon that is "bow-legged", has fragile, feeble, or crooked legs or arms, is more than likely exhibiting signs of metabolic bone disease from calcium and/or UVB deficiency. Also make sure its grasp is strong and has no problem climbing on branches.
 * be able to support its body weight – a veiled chameleon that cannot lift its body off of the surface its hands are grasping onto, or has trouble with performing such a task, is unhealthy, and is evidence of a variety of possible health complications;
 * have alert eyes and head movement - a chameleon that has its eyes closed for long periods of time, has slow eye movement or lethargic head movement is unhealthy, and could indicate a variety of sicknesses. Also ensure that the chameleon does not have sunken eyes, as this indicates the animal regularly undergoes dehydration and high levels of stress;
 * has a healthy nasal system - a chameleon that has a white mucus in its nostrils, or has a green or light-colored mucus in its mouth may have developed any of a wide variety of nasal infections. Mouth rot is a common illness in chameleons and can be identified by a cheesy and/or green matter. You can always check for this by first placing the chameleon in your hand while lying the other hand on top of the animal, so as to cover or restrain it. If the chameleon lies placidly in your hand and closes its eyes, it is sick. If it gapes and hisses, then check inside its mouth for signs of mouth rot indicated by any cheesy matter. Moderate mucus should be tolerable, though it is at the discretion of the customer and an experienced veterinarian.

Veiled chameleons can be commonly purchased from pet shops, reptile expos, and mail order. Avoid obtaining a veiled chameleon from one who lives in an area where wild chameleons are common, from a trade-off, or from an inexperienced owner who can no longer care for the animal, unless (as mentioned before) your intent is to rescue the animal. Also make sure that the breeder or seller is reputable. Check any transaction history if possible, read reviews, or inquire with a veterinarian.

Metabolic bone disease

 * (caused by calcium and/or UVB deficiency)

Nasal infections

 * mouth rot

Dehydration

 * (can lead to kidney failure and gout)