Lighting  & UVB Additional Information

UVB Gradient:

When placing UVB lamps over a terrarium, it is imperative that the lamp is positioned in a way that creates a UVB gradient in the habitat. UVB will be strongest close to the lamp, and will gradually decrease with distance. This can often be achieved by placing the lamp fixture above the terrarium and off to one end of the habitat. Verify that the desired UVI levels and gradient are achieved using the UVI meter. The habitat must be large enough to provide this gradient and allow reptiles to photoregulate (adjust their exposure to UVB as needed). For all zones, always provide a shelter for reptiles to retreat completely from any light and UVB exposure.

Shade method vs. Sunbeam method:

Two methods of providing UVB for reptiles are described by Frances Baines. Ferguson UVI zones 1 and 2 approximate UVB levels that would be found in the shade, in the canopy of a tree, or on partly cloudy days. These levels are often achieved over the majority of the habitat using fluorescent lamps that span the length of the terrarium, just as the levels would be uniform outdoors in the shade or on an overcast day. When providing UVI for zone 3 and 4 species, ideally, the Sunbeam method should be used, where the appropriate zone is provided over about half the length of the terrarium, and higher levels (in the range UVI 3.0 – 7.0) are created over just the basking site, to simulate direct sunlight. A gradient down to zero UVI is achieved in the rest of the habitat.

Temperature gradient:

The biological process where vitamin D is synthesized in the skin following exposure to UVB can only occur when the proper temperatures are present. This process is heat dependent, so it is critical to research the temperature requirements of various species and provide the “POTZ” (preferred optimum temperature zone) in their habitat. Whenever possible, place the heat source as close as possible to the UVB source.

Watch for abnormal behaviors:

It is important to monitor the reptile’s behavior following the introduction of a new UVB lamp. If the reptile spends unusually long periods of time basking as close as possible to the UVB and heat lamp(s), then the temperature and/or UVI level may be too low for that species. If a species appears to be trying to avoid the UVB lamp, spending most of its time as far from the lamp as possible then the lamp may be too strong. Under ideal conditions, reptiles should spend some time basking, and should also move throughout the habitat to perform natural behaviors (feeding, sleeping, etc.). Be sure to check both the UVB and temperature levels in the habitat. Reflectors and screen mesh: Reflectors can have a great effect on the total UV output from a lamp, sometimes increasing the measured UV output by 30% or more when an effective reflector is used. Be sure to test your lamp in the fixture that will be used on the habitat. Additionally, screen mesh between the lamp and the basking site usually causes a significant reduction in UVB. The percentage of UVB reduction varies with different types/sizes of mesh. Be sure to check UVI levels through the mesh to determine the percent reduction caused by the mesh being used. Glass and most plastics filter all UVB emissions and should not be placed between the lamp and animals.