UVB and reptiles!
Distinguishing nocturnal (night active) reptiles from diurnal (day active) reptiles
The rule is about 99 percent accurate: Nocturnal reptiles tend to have pupils that are slit like a cat’s eye, and diurnal reptiles tend to have pupils that are round like ours.
The importance and relationship between UVB, calcium in diet and vitamin D
Vitamin D maintains calcium and phosphorus levels, critical for bone health. The sun’s ultraviolet (UV) light coverts a precursor (7-dehydrocholesterol) in the skin to vitamin D. This converted vitamin D is used by the body to uptake calcium from the digestive tract and enables the body to use it in the formation of bones. If any one of the three parts of the equation (vitamin D in the diet, or the precursor in the skin, calcium in the diet and the exposure to ultraviolet light) is missing, then the body becomes calcium-deficient and the end result is metabolic bone disease (MBD). This is equivalent to brittle bone disease in humans. In reptiles, if sufficient bone loss occurs, the body tries to shore up the degrading bones by creating fibrous tissue around the bones.
When this happens, the long bones in the reptile’s body take on a “Popeye” appearance. The legs and arms appear to be very muscular due to their increased girth. The enlarging of these limbs is not due to muscle growth, but the increase in fibrous tissues that are attempting to support the long bones in the body of the reptile. Before this change in physiology becomes apparent, the reptile often experiences a general weakness in the body and the appearance of fine tremors in the toes and fingers. This twitching is usually the first sign that some part of the uvb/calcium equation is missing and if measures are taken immediately (correcting whatever part of the husbandry is missing) then the start of MBD can be reversed usually with no long term health consequences for the reptile in question.
Now the calcium in the diet of the reptile is something that has to be addressed. All insect prey and some vegetables are deficient in calcium. For reptiles the ratio of calcium to phosphorous in the diet should be two parts calcium to one part phosphorous (2:1). Crickets for example are 0.13 to 1 for calcium to phosphorous. This has to be corrected before the cricket is fed to a reptile. One way to do this is to dust the cricket with calcium before feeding it to the reptile. When choosing your calcium powder to dust the crickets with, pay attention to the labeling. Some calcium exists on the market that includes phosphorous in its makeup. These supplements are usually 2:1 for calcium to phosphorous. If you use this type of dust you are not increasing the calcium intake of the reptile since the powder is balanced and the cricket is not. You need to use a calcium only or a calcium/vitaminD3 powder to increase the calcium ratio of the food for the reptile.
Some vegetables are also deficient in calcium, some are high in calcium but contain phytates and or oxalates which are naturally occurring chemicals that bind to calcium molecules in the body preventing them from being used by the reptile. Other vegetables that might cause a problem in excessive quantities are called cruciferous vegetables. These vegetables are members of the cabbage family and contain substances called goitrogens that can inhibit the absorption of iodine which can lead to goiter.
Vegetables with a good calcium ratio:
- Collard greens
- Mustard greens
- Dandelion greens/flowers
- Nasturtium greens/flowers
- Hibiscus leaves/flowers
- Escarole
- Turnip greens
- Carrot tops
- Parsley
- Leeks
- Green onions
Vegetable that contain phytates/oxalates and should be used occasionally but should not make up a high percentage of the diet:
- Spinach
- Chard
- Beets and beet greens
Cruciferous vegetables:
- Kale
- Broccoli
- Brussels sprouts
- Cabbage
- Cauliflower
- Bok Choy
Some further points:
- UVB is only effective within 12-18" of the bulb’s surface
- UVB cannot pass through anything that water cannot pass through (e.g. plastic or glass that is between the UVB bulb and the reptile filter out 100% of the UV and the reptile receives none).
- UVB bulbs have to be changed every 6–9 months as their UVB output degrades to the point where it is no longer effective.
- Dusting of calcium in essential to off set the phosphorous content of most reptile food (e.g. insects)
Sources:
Cricket calcium ratio: Rep-Cal Supplements, Ca:P ratio table
Vegetable oxalates/phytates and cruciferous: Green Iguana: The Ultimate Owner’s Manual by James W. Hatfield III
Does glass filter UVB light?
Glass filters out 95% of all UVB rays. Aluminum screen filters out about 30%. If a screen cover is used between the light source and the animal, be sure the screen has 1/8 inch or larger holes. Also, make sure your light source is within 12 inches of your animals
UV Lighting and Snakes
UVB Lighting
Most snakes DO NOT have high UVB requirements. (Diamond pythons are an exception) Snakes derive their vitamin D3 from the livers of the animals they eat (mice, rats, etc.). Amphibians also do not seem to require UVB.
UVA Lighting
Snakes and amphibians will benefit from UVA lighting. UVA is in the visible range, and is responsible for normal behaviors such as feeding, diurnal movement, mating etc. Why UVA? Many species of snake are active during the day and are stimulated to be more active by UVA light. Examples are snakes such as indigos, racers, tiger rat snakes, pine snakes, and bull snakes. This type of lighting simulates sunlight without providing UV-B light. The benefit is increased activity, appetite and improved breeding success. These benefits are a result of improved hormonal cycles associated with daily light cycles. Full spectrum light also improves the display quality as colours are much more vibrant and natural.
Ginnette