Do corn snakes need or want ultra violet light? The vitamin D question.Pete Milligan of Evolution Reptiles

Pete Milligan of Evolution Reptiles, Kidlington

For years it had been thought that corn snakes, a popular and easy reptile pet, don't need special lighting. They just need a heat gradient and a proper diet of defrosted rodents.  The vitamin D which they needed came from their diet (just as cats and other carnivores get their vitamin D from their diet).
Vitamin D is essential for health. It regulates the calcium that is needed to make bones. Studies of vitamin D in humans and birs and mammals are beginning to show that it is essential for good health in other ways, possibly playing a protective part against human breast cancer. All in all it is an important vitamin.
We still don't know for sure how much vitamin D is needed by various reptiles. Do corn snakes need it via ultra violet light? Is their diet giving them enough? Corn snakes, if they are fed the correct diet (not the mince that was recommended as feed for snakes in Ireland in the l960s!), should have enough vitamin D to survive.  But what is enough? Enough to survive? Enough to breed? Enough to flourish?
A group of scientist in Louisiana State University investigated further (see below). Over 4 weeks during which the snakes were not fed, they exposed one group of snakes to UVB radiation, and one group were kept without it. They tested the level of vitamin D in the blood. The levels of radiation were also measured.
The group without UVB radiation showed no change in their vitamin D level: the group with UVB radiation had a higher level of vitamin D. So corn snakes can and will increase their vitamin D level if they are exposed to ultra violet light.There was no significant difference between the two groups in weight at the end of the period.
So now we know for sure that, given UV light, corn snakes will make vitamin D from it, and have a higher level of it in their bodies than a level just obtained from their diet. We can no longer make the assumption that UV lighting is unimportant for corn snakes. "The findings of the present study suggest otherwise," say the scientists. This is the first step towards finding out how important it may be and what levels are needed not just for survival but for good health and happiness (yes, reptiles do feel emotion!).
Pete Milligan of Evoluton Reptiles says: "A snake will benefit from UV - at the moment there isn't enough evidence to say that it is essential."

• The reptile relationship survey has now closed. Thank you everybody who did it.

• *Acierno et al., 'Effects of ultraviolet radiation on plasma 25-hydroxyvitamin D3 concentrations in corn snakes (Elaphe guttata),' American Journal of Veterinary Research, 69, 294-297

The third eye - is your pet reptile on a higher plane that you?

The "third eye"on a lizard - Wikipedia

The "third eye" was the seat of the soul, according to Rene Descartes, the French philosopher whose reductionist opinion of animals encouraged vivisection and other cruel animal experiments.
He couldn't have been more wrong. The third eye in reptiles is a functional adaptation which may allow them to "see" predators, like birds of prey, approaching from above. Its ability to function varies from species to species. In some it even has a lens and retina. In most reptiles the parietal eye doesn't have these but may be able "see" light and shade differences. There's a good description here.
The reptile parietal eye, connected to the pineal gland which is similar to the pineal gland deeper in the brain of mammals, responds to light and releases the hormone, melatonin, which regulates circadian rhythms like the sleep wake cycle. It influences the secretion of sex hormones too. And strangely it is the only bit of the middle brain that isn't paired. It's also got a good blood supply from a nearby artery.
In modern new age mysticism the third eye leads to  higher inner consciousness. With your third eye you see or experience stuff that ordinary non-enlightened humans cannot. Could your pet snake or lizard be on a higher plane that you are?

My Reptile Relationships survey is closing at the end of the month.

The third eye - not so much the seat of the soul as a way to regulate circadian rhythms.

The "third eye"on a lizard - Wikipedia

The "third eye" was the seat of the soul, according to Rene Descartes, the French philosopher whose reductionist opinion of animals encouraged vivisection and other cruel animal experiments.
He couldn't have been more wrong. The third eye in reptiles is a functional adaptation which may allow them to "see" predators, like birds of prey, approaching from above. Its ability to function varies from species to species. In some it even has a lens and retina. In most reptiles the parietal eye doesn't have these but may be able "see" light and shade differences. There's a good description here.
The reptile parietal eye, connected to the pineal gland which is similar to the pineal gland deeper in the brain of mammals, responds to light and releases the hormone, melatonin, which regulates circadian rhythms like the sleep wake cycle. It influences the secretion of sex hormones too. And strangely it is the only bit of the middle brain that isn't paired. It's also got a good blood supply from a nearby artery.
In modern new age mysticism the third eye leads to  higher inner consciousness. With your third eye you see or experience stuff that ordinary non-enlightened humans cannot. Could your pet snake or lizard be on a higher plane that you are?

My Reptile Relationships survey is closing at the end of the month.

Is my pet snake too fat? Or too thin?

Because we humans eat every day, it's difficult for us to get our head round the fact that reptiles don't need to. They need less food than we do because they don't have to heat up their bodies - the sun does that for them.
So many pet snakes end up too fat. Sometimes this is because their owners continue feeding them the same amount of food throughout their life. When they are young and growing, they need more than when they get to middle age - just like humans!! So if you feed your mature snake as often as you did when it was young, the result will be a portly animal.
With corn snakes, the fat is likely to accumulate just above the tail - look at the photo on the right and you will see the tail is growing out of a kind of bulge. That's usually a fat snake. If however it is an animal you have just bought, or if that lump occurs suddenly, then you need to take your snake to a vet to make sure it isn't some kind of illness.

The other mistake is not to feed your snake enough. That often occurs because if a reptile is kept at the wrong temperature without enough heat, their whole metabolism slows down. They lose their appetite and just go off their food. Slowly, their colours fade, their spine or ribs start showing and they become weak with starvation. Many of them will be dying before they get to a vet.
So how often should you feed your snake? How much? The detailed answers to this question depend on the snake's species. Get a good online care sheet from Evolution Reptiles here or from the RSPCA. Don't just rely on friends or forums  because the quality of advice will vary.
Finally, how do you decide if your snake is fat or thin or just right. Take a look at the very rough sketch below. It shows a cross section of a snake. The triangular shape on the left is a snake that is too thin - you may be able to see an outline of the spine at the top or even its ribs. The snake in the middle is the right size, a sort of dome-like shape with a flat bottom which is where its muscles pull it along the ground. The snake on the right is round all over - and too fat.

Are reptiles intelligent? Can they learn? Amazing Reptile Fact 2.

Dr Anna Wilkinson with a bearded dragon. A still from Ingenious Animals
Available on BBC IPlayer till Sept 28 2016.

About 20 years ago I asked a so-called reptile expert whether snakes could think? "No," he replied. "They have a primitive brain."
"How do they find their way about?" I asked him.
"Instinct. Pure instinct." he replied.
Reptiles have a reputation for being stupid animals - " a lower form of life," more "primitive" than mammals, just a bundle of instincts, without feelings, unable to learn.
Wrong.
This slur on reptile intelligence came about for several reasons. One was the rather odd idea we have of the role of intelligence in evolution - a kind of tree of life with clever man right at the top, and all the other animals below, getting stupider the lower they appear. Like an intelligence class system - man as master of the world, animals as peasants or serfs. It's a self-important human idea. Even a mollusc, the octopus, can be pretty bright and may even be able to use tools, something we used to think only humans did. And although reptiles preceded mammals, they have been evolving since then. So even if they started off dumb in the days of the dinosaur (and we have no reason to suppose this) they have been evolving since then.
Work at Lincoln University, under the direction of Dr Anna Wilkinson, has shown that tortoises  can navigate their way through mazes. They can even follow the gaze of a fellow tortoise to find out where it is looking. Lizards can learn whether a food reward is on the left or the right. Tortoises can recognise the difference between a picture of food or the picture of a nonfood object.
Even more extraordinary is that a bearded dragon can learn from watching another bearded dragon tackle a problem. From a video, no less. This was demonstrated in a BBC programme, Ingenious Animals, in which one of Dr Wilkinson's lizards watched a video of another lizard pushing aside a glass door to get at some meal worms. Before he saw the video, he spent a long time trying to learn how to do this. Once he had seen the video, he got the idea far more quickly.
So.... reptiles aren't stupid.

Click here to watch the bearded dragon experiment on BBC until September 28 2016. The bearded dragon part is about two thirds of the way through.

Wilkinson, A.  & Huber, L., (2012), Cold-Blooded Cognition: Reptilian Cognitive Abilities,’ in eds Vonk, J. & Shackleford, T. K. The Oxford Handbook of Comparative Evolutionary Psychology, Oxford, UK, Oxford University Press, 129-143.