Lighting is a scientific matter when it comes to herptiles, so retailers must relay this important information to the consumer.
Within the past 30 years, the hobby of keeping reptiles and amphibians as pets has evolved from near total obscurity into a booming sector of the current pet industry. As our knowledge of the specific captive requirements of various herp species has improved, so has the quality and selection of products available to the consumer.
Various devices for temperature control and measure, heating and feeding have all come and gone over the years, but it is with lighting that the most exciting and tangible advances have been made. Lighting is a scientific matter when it comes to herps. Like marine aquariums, only certain types of light are appropriate, or even effective, in keeping plants and animals happy and healthy. There is also a plethora of products specially designed for reptile use that have proven quite effective.
Light that is visible to humans represents only a small portion of the electromagnetic spectrum. Generally, we cannot detect light traveling at wavelengths below 380nm (nanometers), but herps can see light at both higher and lower wavelengths.
Ultraviolet B light (UVB) is often discussed in reference to providing light for diurnal reptiles. UVB is light in the range of approximately 280nm-320nm. While this light is invisible to us, many reptiles can see it, and it serves an important physiological purpose for them.
When a comfortably warm reptile is exposed to light in the UVB range, provitamin D is formed within the skin cells. Rapidly, it becomes previtamin D3, and then, more slowly, it becomes vitamin D3, which is finally carried away in the bloodstream to the liver where it plays a large role in the metabolism of dietary calcium.
UVB can be provided in two ways: via access to unfiltered direct sunlight (more common in animals housed outdoors) or from specially designed bulbs that produce a predetermined level of UVB. These levels are often represented in the product name as a number such as 2.0, 5.0, 8.0 or 10.0. These numbers represent the percentage of overall light that the bulb emits that falls within the UVB range.
It should be noted that these bulbs all emit levels of ultraviolet A (UVA) sufficient for the physiological needs and psychological well being of reptiles. It has been determined that without UVA light reptiles are essentially color blind, and in its absence have trouble hunting and reproducing in captivity.
UVB-emitting bulbs are available as linear (standard) fluorescent bulbs, compact fluorescent bulbs (fluorescent loops or spirals with a standard, screw-in base) and self-ballasted mercury vapor bulbs, the latter of which produce heat as well as light. The type and intensity of bulb used will vary based on the species being kept and the type and style of enclosure being utilized.
While each situation is unique, some generalizations can be made in regards to UVB requirements. Amphibians and nocturnal reptiles can typically be maintained with little or no UVB. These animals, which in nature would seldom bask in the sun’s rays, are able to procure all of the vitamin D3 they need by means of a varied diet, and in captivity via manufactured calcium and vitamin supplementation.
Snakes tend to similarly derive all their vitamin and mineral needs from their diet of nutritionally sound whole prey items, and similarly can be kept without UVB, or with minimal amounts provided by bulbs in the two percent UVB level.
Tropical and sub-tropical species have proven to thrive when exposed to lights that provide five percent UVB and are fed a properly diverse and supplemented diet. Desert species, or animals being kept in large enclosures, require higher levels of UVB. For these animals, eight percent UVB or 10 percent UVB bulbs may be warranted. Mercury vapor bulbs tend to be high wattage bulbs with maximum heat and UV output. They are ideal for sun worshiping species, animals kept in large enclosures or when heat and UVB light are desired from a single bulb.
Getting Into Specifics
All technicalities aside, proper herp husbandry boils down to temperature, exposure to appropriate lighting and diet. Below I will outline the lighting options for some common pet herps. This information should be used as a general reference as it applies to this column. For more in depth information on the husbandry requirements of these animals, further reading is encouraged.
- Bearded dragons are a desert species and should be provided with a basking light combined with a high output UV bulb. Bearded dragons maintained in larger enclosures can be outfitted with a mercury vapor lamp of the appropriate wattage.
- Green iguanas are a tropical species with moderate to high UVB needs. A basking lamp should be provided, as should a UV bulb in the five percent to 10 percent range, based on cage size. As a result of the large size attained by this species, and the similarly large enclosure required, many keepers opt to use multiple mercury vapor bulbs, or mercury vapor bulbs in conjunction with fluorescent lighting.
- Green anoles are considered sub-tropical due to their wide and ever expanding range. They do best when provided with a basking light of the appropriate wattage and a fluorescent UV bulb.
- Day geckos, as their common name indicates, are diurnal by nature and require moderate to high levels of UVB in conjunction with adequate basking spots provided by heat bulbs. Use of either five percent or 10 percent (for taller enclosures) UVB bulbs should be sufficient for most species.
- As far as lighting goes with chameleons, the use of mercury vapor bulbs is recommended. Because they are typically kept in tall enclosures with a relatively small footprint, these bulbs allow the keeper to use a single fixture, which is often all there is room for, to handle both heat and UV. For species in which high heat is not needed, a lower wattage heat bulb can be used in conjunction with a 10 percent UVB compact fluorescent bulb.
- Leopard geckos are desert dwellers, but nocturnal as well. As a result of their lifestyle, they get most of the vitamin D3 and calcium they need from a varied and properly supplemented diet. Therefore, the use of UV lighting is not warranted. Low output (two percent) bulbs can be used to facilitate a healthy photoperiod for the animals.
When selling a reptile, it is of upmost importance that the lighting information be considered and passed on to the consumer. While some hardy species may seem to be okay without appropriate lighting, this is only temporary, and lack of light will affect the long-term health and well being of the animal.
Jonathan Rheins is an avid herpeteculturist. He is a manager at LLLReptile & Supply Co. in Escondido, Calif. and, when not fulfilling that position, spends his time working with and writing about a wide variety of exotic reptiles, amphibians and invertebrates.