Snakes and Nocturnal Lizards
Snakes, by virtue of the fact that they have evolved to eat whole prey, are pretty easy to feed and get virtually all their calcium and vitamin D needs through their diet.
Nocturnal species of lizards do not get much exposure to UV light in the wild, so do not have any special requirements for UV light producing bulbs.
Snakes and nocturnal lizards therefore simply need enough light to provide a day - night cycle appropriate for the species, and a regular incandescent bulb is fine. As discussed on the previous page, bulbs used for heating and light are sufficient for these species.
However, many lizards and all turtles and tortoises need exposure to UVA and UVB light, which must be provided wither by regular exposure to sunlight or special lights.
Why UV Light is Important?
Ultraviolet light (UV) is important in the production of vitamin D3, which is necessary for calcium metabolism. Vitamin D3 is produced in the skin with exposure to UV light (from sunlight). While vitamin D3 can be supplemented in the diet, it appears some reptiles, such as iguanas, make better use of vitamin D3 produced within their bodies than that provided in vitamin supplements. Sunlight is an impractical source of UV for most owners (UV light is blocked by glass, so exposure through windows is not a viable option). UV can be provided by special light bulbs.
UV light is made up of UVA, UVB, and UVC wave lengths. UVC is harmful, and UVA and UVB is what the reptiles need. The most crucial consideration is the amount of UVB produced, and this is where the selection of an appropriate bulb is necessary.
Faced with a huge range of light bulbs in a pet store, there is sometimes confusion over which is the best kind to get. Make sure you get a full spectrum light, that produces more than 1.1 % UVB. Melissa Kaplan, author of Iguana for Dummies, recommends either the Durtest Vita-Lite or Zoo Med's Reptisun as good lights. Over time, the production of UVB diminishes, and UVB bulbs should be replaced every 9-12 months.
For those species that require a UVB producing light, another source of light is generally required, as either a source of bright white light and/or heat. When placing the various heating and lighting elements, they need to work together. Place the UV lights and the basking light at the same side of the enclosure, or the reptile might spend its time basking and be to far away from the UVB lamp to reap its benefits.