Do snakes need a UV lamp?
Please can you advise me about full spectrum lighting for snakes. I keep a common boa, in a vivarium measuring 1.8×0.6m (6x2ft). What sort of lighting set-up would be suitable?
A lot of research has been carried out into this area recently, but there is still much more to do! As a snake keeper myself, I believe it is vital to start every bit of research by concentrating on the behaviour of the animal in the wild. I feel certain that all of the secrets and mysteries of the species’ requirements are hidden in that wild animal. It is this data that we can use to build on our knowledge about the care of snakes (and other creatures too).
It was once – and I think quite wrongly – assumed that snakes could obtain all the vitamin D3 that they need from the livers of a mammalian prey source. This thinking, however, does not take into consideration many of the other chemical and hormonal changes that take place inside the body of an animal after its exposure to natural sunlight.
The vitamin D3 cycle is dependent on hundreds of different changes here and presently, we simply don’t know what these actions, changes and functions impact, in terms of other reactions and responses in the animal. We know that exposure to sunlight can help with brain function and boosts levels of serotonin (a vital neurotransmitter) though, and that many by-products of the vitamin D3 cycle as it occurs in nature affect other areas of reptile physiology.
We also know that snakes use the wavelength
that we call UVB in exactly the same way as any other reptile (and most other forms of life, including ourselves) and as such, they would be sure to make use of this ability in the wild. We also have discovered that snakes, like all other reptiles, are tetrachromatic. This means that they have a fourth (= tetra) colour receptor in the eye, allowing them to see a whole array of colours that are not visible to us, as our vision is only trichromatic.
Reptiles can therefore see in the UVA spectrum of light, which is believed to enhance their colour vision significantly, allowing them to see up to 100 million colours – around 99 million more than we can! No UVA provision in the form of lighting for their quarters means that they cannot utilise this colour vision.
Tetrachromacy allows snakes to track prey, locating the scent trails of rodents as an example. They can also use this ability to find a mate, as there are fluorescent patches that are visible within their scales to other reptiles, but not to humans. Snakes may therefore display signs of sexual dimorphism, allowing males and females to be distinguished visually from a distance, which are again invisible to us.
Behaviour in the wild
Snakes do obtain Vitamin D3 from the livers of mammal foods sources of course, but we can never be assured of the quality of mass produced rodents. How do we know the liver function and D3 content? Snakes would also be eating a huge variety of other food sources in the wild, none of which would be largely sterile, compared with white laboratory mice and rats!
Their prey is likely to include birds, eggs, insects, bats, fish, mammals, other reptiles and amphibians too. Even with this variety of wild foods, snakes still have this amazing ability to use sunlight in all of its wavelengths, so clearly, it is not just related to vitamin D3. The non-lighting argument for most species of snake no longer stacks up for me.
Both nocturnal snakes and highly crepuscular ones that become active at dusk are still commonly found sleeping in the trees during the day, benefiting from exposure to full sunlight. Look at green tree pythons and mangrove snakes for two examples of such behaviour. Also, you certainly don’t need to be awake to benefit from the D3 cycle. If you had to be awake, it wouldn’t be possible for us to get burnt in the sun when we fall asleep on the beach!
If you look at most snake species, they are documented as resting in the canopy (as with mangrove snakes) or grassland during the day (such as corns, milks, kings, hognoses and (pythons) or basking near ponds (garters, dice snakes and the like). Relatively few species spend their whole life in a cave – perhaps some cave boas or flower pot snakes – but in these cases, their ability to see UV may still allow them to benefit from sunlight filtering down into the cave.
Reticulated pythons are commonly found basking during the day, even if they use burrows and caves too at certain times. Another clue is the colouration of some snakes. Black patches allow light and heat to be gathered and used quickly.
Choosing a lamp
It is obviously important to fi t any lamp in the vivarium in a way that will be of maximum benefit to the snake. So start by searching for the species’ locality online, and look up the weather patterns and UV index (UVI) here. This will not only help you with lighting the enclosure, but will also give you clues as to the most suitable décor to include as well.
You then want to light only a portion of the vivarium – typically just around half of the enclosure at most, corresponding to the upper UVI. Always do this on the hot side so that heat and light are at the same end. By using a shorter lamp than the vivarium, this creates usable areas of light and shade, as per the “light and shade method”. This then allows the snake to self regulate its exposure to the light, in the same way as it can adjust its heat exposure via the thermal gradient that exists in the enclosure. The same principle applies.
Taking into account the size of your vivarium and the species in question, I would either use a D3 (6% UVB) T8 lamp and reflector or the D3 (6%UVB) T5 lamp. I would choose either the 18W 24in in T8 or 24W 22in in T5. This system can then be placed at the hot end of the vivarium, so that there is a usable photo gradient across the enclosure, as mentioned.
Leave the light on to correspond to the normal period of daylight in the area where the snake originates. This can be more significant in more temperate species, where
this period varies through the year. Observe your snake, record its behaviour and increase or decrease the period of light exposure according to the snake’s movements. If it is hiding all of the time for example, decrease the exposure, or alternatively, should it be out basking constantly, you can increase the photoperiod accordingly.
Regarding the snake’s safety, and especially in the case of arboreal and powerful individuals, it is recommended to make a small box section around the lamp out of batten and Twilweld aviary mesh. This will prevent the snake from curling around the lamp.
Most keepers who have tried this method have reported that their snakes become more active, feed with greater vigour and appear more brightly coloured. There have been some reports too of problem shedders starting to shed properly, and baby snakes putting on weight more consistently, over a shorter period of time, indicating that the light could be assisting metabolic processes in the body.
One thing is for sure that we are all still learning. This is the very best advice that I can give you at this present time, based on the science that is available to me. But I do look forward to the next 5-10 years when I expect that our understanding in this area will have increased rapidly and significantly.
© John Courteney-Smith
Taken from “Practical Reptile Keeping” magazine