To keep your veiled chameleon (Chamaeleo calyptratus) healthy, you must provide him with a heat lamp for basking, as well as a full-spectrum light so he can process his dietary calcium properly. Most light bulbs that produce heat do not produce the right type of ultraviolet radiation your pet needs, while most bulbs that produce a broad spectrum do not produce heat, thereby necessitating the use of two different types of lights. Manufacturers of another type of bulb – called a mercury vapor bulb -- claim that it produces both heat and ultraviolet light; however, these bulbs present other challenges.
The Heat Light
Like many other reptiles, veiled chameleons require external heat sources to regulate their internal temperature. While you can use non-light-emitting heat sources for many other reptiles, chameleons prefer visible light for basking. Wild chameleons bask in the sun to warm themselves, so try to emulate the sun’s rays by placing an incandescent bulb and light shroud over your pet’s cage. Aim the light at a prominent perch in your lizard’s enclosure, which will become his basking spot.
Monitor the temperature of the basking site with a digital thermometer. The ideal basking temperature for a veiled chameleon is about 90 degrees Fahrenheit; adjust the wattage of the light bulb to maintain temperatures within this range.
The Importance of Ultraviolet Light
Chameleons – and many other diurnal reptiles – require exposure to ultraviolet light to produce vitamin D3, which is necessary for proper calcium absorption. However, not all ultraviolet wavelengths help accomplish this task. Chameleons require light between 280 to 315 nanometers – called UVB – for this purpose.
Several commercially produced fluorescent bulbs produce such wavelengths, but you must install and use them properly to ensure your lizard is getting the light he needs. For example, glass and plastic both filter UVB rays, so you must place the light on top of screen or mesh. Additionally, the UVB-producing capability of these lights decreases over time, necessitating frequent replacement. Follow the manufacturer’s instructions regarding the replacement schedule.
Too much ultraviolet radiation can be harmful, so try to provide a photo gradient by blocking the light at one end of the cage. Some lizards can see ultraviolet light, which enables them to move throughout the cage to bask in the light or avoid it as necessary. Try to keep the UVB-producing light bulb within about 12 inches of your lizard to facilitate adequate absorption.
Use a lamp timer for both the UVB lights and the heat lights to maintain a consistent 12-hour photoperiod.
The One Bulb Option
Several different self-ballasted mercury vapor lights produce both heat and UVB. While presumably a convenient option for lizard keepers, the bulbs are often considerably more expensive than fluorescent fixtures. Additionally, because the bulbs produce both heat and UVB light, they may produce too much heat, thereby requiring you to move the light farther away from the cage, which reduces the amount of UVB your lizard can absorb.