Do Snakes “NEED” UVB?
Snakes are animals that have previously been kept and bred successfully without UVB lighting. However, in recent years more research has been published on the effect UVB lighting has upon snakes. So lets do a dive into if snakes should have UVB.
When studying how snakes use UVB, researchers extract blood and measure the amount of 25-hydroxyvitamin D3 circulating in the blood plasma. If there is a rise in levels in test group snakes with UVB, compared to a control group of snakes without UVB, its indicative that they are able to cutaneously synthesise vitamin D under UVB. Most studies published on snakes would suggest that most snakes should be provided with UVB lighting, here’s why.
UVB’s Effect On Corn Snakes (Pantherophis guttatus)
A paper published by the American Veterinary Medical Association investigated if corn snakes had increased 25 hydroxyvitamin D3 concentrations with access to UVB, compared to a control group of corn snakes without access to UVB. A rise in 25-hydroxyvitamin D3 would prove that corn snakes are using UVB to increase vit D levels.
12 corn snakes were used in total, 6 were given UVB and 6 were not. Blood was extracted and the levels of 25-hydroxyvitamin D3 were measured at the start and at the end of a 28 day period. At the end the blood concentrations between the groups differed significantly.
The control group went from 57.33 nmol/L on day 0 to 57.17 nmol/L on day 28. That’s a 0.27% decrease. It basically remained the same.
The UVB test group had a mean concentration of 196 nmol/L and the control group had 57.17nmol/L. The test group rose from 63nmol/L on day 0 to 196nmol/L. That’s a 211.11% increase.
Table 1: 25-hydroxyvitamin D3 level change in corn snakes from day 0 to day 28.
UVB’s Effect On Burmese Pythons (Python bivittatus)
Figure 2: Burmese python (Python bivittatus). Image by Christine Sponchia from Pixabay
A similar paper was published in the Journal of Zoo and Wildlife Medicine, but this time investigated Burmese pythons and the time frame was 310 days. A limitation of this study was that it was only on four snakes, of which only two had suitable data for day 0 and day 310 after blood withdrawal inconsistencies.
On average the two snakes had 39nmol/L on day 0 and 244nmol/L on day 310. That’s a 525.6% increase.
Table 2: 25-hydroxyvitamin D3 level change in Burmese pythons from day 0 to day 28.
Why Don’t Snakes Overdose From UVB?
Cutaneous synthesis of vitamin D3 under UVB is a self limiting process. When the upper threshold of vitamin D is met, excess formed in the skin is recycled into inert byproducts. Basically the brakes get put on, and overdose does not occur.
So here is a hypothetical id like you to think about, if there’s breaks to stop them from overproducing and reaching overdose. Then it is likely to occur near or just above optimal levels. So if the snakes were already near optimal levels then you could argue that you would see minimal or no increase at all. But when there are 211% and 525% increases, this is unlikely to be true. However, the animals are not showing outward signs of deficiency either, so it is likely they have enough for calcium metabolism, day to day functioning and reproduction. But they would be without any of the further health effects of being at optimal levels.
UVB’s Effect On Ball Pythons (Python regius)
Figure 3: Ball Python (Python regius) basking under UVB lighting, Image provided by Ellie Hills.
A similar study of the same type was performed on ball pythons. The study used 14 ball pythons which had never experienced UVB. The UVB test group was composed of 6 females and the no UVB control group was composed of 5 males and 3 females:
On day 0 the test group mean levels were 197nmol/L and were 203nmol/L on day 70.
On day 0 the control group was 77.7nmol/L and on day 70 were 83nmol/L on day 70.
The lack of significant increase could be taken as an indicator the species shouldn’t have UVB, if these results were not so dubious. All of the females across both groups had extremely high levels of 25-hydroxyvitamin D3 on day 0 compared to the control group. This made them non comparable.
#1 Possible Explanation: The females Were Developing Eggs
The authors of this study did not evaluate the reproductive status of the snakes but recognise that the study was performed between July and September, which is the season that some of the snakes had produced eggs before. There is a possibility that egg production raises serum 25-hydroxyvitamin D3 and any vitamin D produced via UVB could have been transferred to developing eggs which require high levels of vitamin D for embryonic development.
This could have been accounted for if they had males in the UVB test group and did not compose it of only females. if there was a notable increase in serum levels of test group males then it would signify that its potentially being used elsewhere in females.
#2 Possible Explanation: Excess Was Recycled Into Inert Byproducts
It could be possible that ball pythons do not synthesise vitamin D from UVB and obtain all they need from their diet. Very high levels to begin with shows they are very good at utilizing dietary vitamin D3.
Its also possible that the very high levels to begin with inhibited the creation of more vitamin D3 under UVB, because cutaneous synthesis of vitamin D3 under UVB is a self limiting process. When the upper threshold of vitamin D3 is met, excess formed in the skin is recycled into inert byproducts. Basically the brakes could have been put on.
#3 Possible Explanation: They Were Not Warm Enough
heat is needed to convert previtamin D3 to vitamin D3. The authors noted that the ball pythons may not have been warm enough for this to occur. The pythons were provided with a temperature gradient of 20-30C (68F-86F) and measured choanal temperatures were 27C (80.6F). It is possible that higher temperatures than provided are needed for conversion to occur.
This study raises a lot of questions but provides little answers due to its methodological flaws. It would be good to see further studies done and to include males in the test group to exclude the influence of egg development on results. More blood work would be very interesting.
What Do Ball Pythons Use UVB For?
Ball pythons do have a visual cone that allows them to see within the UV spectrum. It’s not totally clear what this is used for, maybe detecting UV reflective rodent urine to select for prime ambush positions, or even the identification of other ball pythons. The same has been found in boa constrictors. Without access to UV, a ball python would be missing some of its ability to see.
Another study published in the journal Plos One found that ball pythons in captivity basked for 2.4 hours a day. It also stated that in a preliminary study, they found that basking spots without UV were used significantly less than basking spots with UV light. The same study found that albino ball pythons only basked for 10 minutes per day.
So ball pythons evolved the cones to see into the ultraviolet spectrum and have been shown to behaviourally seek out UV for basking opportunities. This raises further questions about the legitimacy of the Ball python bloodworks.
Furthermore, if a ball python and a Burmese python are members of the same genus and are similar enough to breed and produce viable hybrids, then it could be argued that it is probable they are also similar enough that they can both cutaneous synthesis vitamin D through UV.
It is not impossible that ball pythons do not cutaneous synthesis D3, however one would have to ask what they bask under it for? Merely for the management of microorganisms on the skin? Just for the “feel good” feelings of beta endorphins?
Regardless they appear motivated to use it and need it to see in their full colour spectrum.
What About Unstudied Snakes?
Figure 4: Authors own Mexican black kingsnake (Lampropeltis getula nigrita) basking under UVB.
Many snake species have not been studied in terms of measuring an increase in 25-hydroxyvitamin D3 and it is likely most never will. However, if representatives of similar groups have and the species shows to use the resource in captivity then you could argue it’s probably that they do.
Do Snakes NEED UVB?
Do they need it to survive? No, I think the many generations of snakes that have been bred and kept without it is evident enough.
But when all is laid out before me and I know everything that happens under the hood when it’s provided, do I consider it a need for my snakes? Yes. Because that’s my baseline.
My philosophy as a keeper is this: I’m here to provide enriching resources and options in a way that creates choices so that my snakes can exercise agency and regulate what they require when they require it.
It solely depends on how much value you place upon the health effects of UV and offering the choice of this resource, how much do you care if they have things beyond the need to metabolize calcium enough to survive and reproduce. Animal welfare science only exists because people care to measure, improve and learn so that captive animals receive more than survive.
And if someone doesn’t care, one could ask why get into reptile care at all? What’s the point in keeping pets if we don’t care?
References
Acierno, M. J., Mitchell, M. A., Zachariah, T. T., Roundtree, M. K., Kirchgessner, M. S., & Sanchez-Migallon Guzman, D. (2008). Effects of ultraviolet radiation on plasma 25-hydroxyvitamin D3 concentrations in corn snakes (Elaphe guttata). American Journal of Veterinary Research, 69(2), 294–297. https://doi.org/10.2460/ajvr.69.2.294
Bos, J. H., Klip, F. C., & Oonincx, D. G. A. B. (2018). Artificial ultraviolet B radiation raises plasma 25-hydroxyvitamin D3 concentrations in Burmese Pythons (python bivittatus). Journal of Zoo and Wildlife Medicine, 49(3), 810–812. https://doi.org/10.1638/2017-0243.1
Hedley, J., & Eatwell, K. (2013). The effects of UV light on calcium metabolism in Ball Pythons (python regius). Veterinary Record, 173(14), 345–345. https://doi.org/10.1136/vr.101555
Hollandt, T., Baur, M., & Wöhr, A.-C. (2021). Animal-appropriate housing of Ball Pythons (python regius)—behavior-based evaluation of two types of housing systems. PLOS ONE, 16(5). https://doi.org/10.1371/journal.pone.0247082
Sillman, A. J., Carver, J. K., & Loew, E. R. (1999). The photoreceptors and visual pigments in the retina of a boid snake, the ball Python (python regius). Journal of Experimental Biology, 202(14), 1931–1938. https://doi.org/10.1242/jeb.202.14.1931
