Ultra violet light. What we know and what we don't know.

Ultra violet light, unseen by us humans, is necessary for most reptiles in order to create the vitamin D they need for healthy bones and a good immune system. Too much of it can cause skin and eye damage. Too little or none of it can cause a lack of vitamin D which in turn produces a vital hormone that regulates bone health and also the immune response.
Many reptile keepers who don't have UV light try to get round the need for it by dietary supplement of vitamin D or by feeding food that contains vitamin D, such as whole mice and rats. But we still don't know how much UV light most reptiles need. Sometimes a UV light is put into the vivarium and lights up the whole of it so the animal cannot escape exposure to it.
Yet in the wild reptiles regulate their exposure to UV light. In the same way they regulate their body warmth by basking. They will bask inUV as long as they need and then shelter from it. Therefore captive reptiles must be given a hiding place, or the UV light must be applied in such a way that they can move from a "hot" UV spot to a "cooler" UV spot.
Most reptile keepers have caught on to the fact that there must be a temperature gradient within the reptile enclosure, so that the animal can choose whether to be in a hot spot or a cool spot. Now we need to provide them with a UV light gradient too.  The heat lamp and the UV lamp should not be combined. A reptile should not have to choose to get too much UV light in order to get heat, or visa versa.
Gary Fergus and colleague decided they would try to work out how much UV light a reptile needed by looking at the animals in the wild and seeing how long they spent exposed to it. It was not easy.
They concluded that keepers of captive reptiles should provide a UV light gradient from maximum to minimum (by providing a refuge). That care should be taken not to produce vitamin D overose by too much supplementary dietary vitamin D.
So far so good. But they highlighted the lack of exact knowledge.
1. How long does each species of reptile in the wild expose itself to UV light?
2. How much vitamin D does the diet of wild reptiles provide?
3. What is the natural circulating level of vitamin D in a wild reptile?
4. How far can the reptile regulate its access to UV light according to its level of vitamin D in the body? ie. does it "know" when its vitamin D levels are low and does it therefore spend more time in UV light?
5. How sensitive is the reptile skin of different species to the absorption of UV light and conversion into vitamin D?
6. What is the ideal level of vitamin D for each species of reptile?
We don't know.

*

Gary W. Ferguson,1 Andrew M. Brinker,1 William H. Gehrmann,1 Stacey E. Bucklin,1 Frances M. Baines,2 and Steve J. Mackin (2010) Voluntary Exposure of Some Western-Hemisphere Snake and Lizard Species to Ultraviolet-B Radiation in the Field: How Much Ultraviolet-B Should a Lizard or Snake Receive in Captivity?' Zoo Biology 29, 317-334.

How do you know if your lizard, or your snake, or your tortoise is stressed?

Muhammed Mahdi Karim photo is here

When animals are under stress, the nervous system responds by releasing adrenaline and other hormones to prepare the body for action. The adrenal glands flood the body with hormones like adrenalin (epinephrine) to prepare the animal for action. Similar hormones are produced in the brain.

For a long time it was thought that cold-blooded animals were “primitive” and therefore did not suffer from stress as much as “higher” animals.Yet reptiles respond in a very similar way to warm-blooded mammals, though their adrenal glands and their hormones are slightly different.

If the snake or lizard or tortoise has to run away, or hide, or do something in response to a threat, then these hormones help them to do it. For instance some lizards shed their tail when chased by predators. But if there is no action available, the hormones just flood the system to no avail. The animal has no relief from emotions like fear. Reptiles in bad conditions of captivity that cannot escape, for instance, will experience the emotion of frustration in countless escape attempts.

This means that they suffer.

And if the stress is chronic, this affects the animal’s welfare. Chronically stressed reptiles (and humans) have a lowered immune system. They are more likely to get various diseases and disorders.

One problem in measuring tis in reptiles is that their response will vary according to their temperature. They cannot produce their own body heat, so when a reptile is cold, its body functions slow down. So the stress hormone levels in a cold reptile will be different from the stress hormone levels in a warm one.

What can we look for? We can look for harmful repetitive behaviours, like the way lizards or tortoises repeatedly push at transparent barriers. We can look for lack of appetite, aggression, and even a change in skin colour in some lizards.  We need to know how a normal reptile behaves, before we can tell how a stressed one behaves.

What can we look for? Diseases and disorders due to stress may involve inability to reproduce, susceptibility to infections, emaciation from lack of appetite or its opposite, obesity.

What can we look for? We can measure the stress hormones or other chemicals in the blood, but taking blood samples, for instance, will cause even more stress. Or we can measure them in the faeces – a better way as it doesn’t hurt the animal.

But….. we don’t still know enough about what is normal for a corn snake, say, or a crocodile, or a boa constrictor, or a Hermann’s tortoise, or a bearded lizard. Each species may differ in the way it responds to stress. We have a lot of research to do.

Read

Silvestre, A. M. (2014) ‘How to Assess Stress in Reptiles, Journal of Exotic Pet Medicine, 23, 240-243.

Too much or too little vitamin D for reptiles? What do we know so far?

Some lizards may use basking not just for heat but for UV light.

By now most reptile keepers realise that too little vitamin D is bad for reptiles. Vitamin D is either absorbed through natural light or through the diet. Although carnivorous reptiles can get vitamin D in their diet: strictly herbivorous reptiles will not get enough just from diet. And it now looks as if relying on diet along, even in carnivores snakes, risks vitamin D inadequacy.
What do low levels of vitamin D do? Vitamin D is important for the growth and development of bones, for the immune system, artery and vein health, and reproduction. So low levels will impact badly on all these functions. We now know for sure that good vitamin D levels are important for the successful reproduction of several captive reptile species.
Vitamin D can be found in supplements that are given to reptiles. But there is a downside to this. It looks as if dietary vitamin D can lead to too high a vitamin D level if supplements are used incorrectly. In reptiles with an overdose of vitamin D, the aorta gets furred up with minerals.  So supplementing vitamin D by diet can be tricky.
Vitamin D levels are also affected by ultra violet light. But there have been no reports yet of vitamin D overdosing because of UV light. Yes, there can be skin damage from "too much" UV light but not vitamin D overdose. There seems to be a mechanism in the skin hat prevents overdose.
So.....
It is safer to use UV lighting or access to natural daylight to give your reptile enough vitamin D. The animal can probably regulate its vitamin D levels to prevent overdose.
Moreover, some (probably not all) carnivorous captive reptiles that get their vitamin D from a diet of mice etc. may well benefit from UV lighting as well. Carnivorous Komodo dragons get more vitamin D from UV light than dietary vitamin supplement. Conversely ball pythons were able to get their vitamin D equally well from either.
What is the take-home message from this? Use of dietary supplements may not be enough and risks overdose if used incorrectly. UVB light on its own will not lead to overdose and is therefore safer. Some reptiles will benefit it even though they get vitamin D from a carnivorous diet.
AND MOST IMPORTANT OF ALL - Keep up with modern developments. This is an area which is still being researched. What was best practice ten years ago is not best practice now. If you think you know it all, you probably don't.

To read more about this go to:

Watson et al (2014), 'Vitamin D and ultraviolet B radiation considerations for exotic pets,'Journal of Exotic Pet Medicine, 23, 369-379.

 

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.

Looking through a glass darkly - can your lizard, tortoise or snake?

This snake has hiding places but the reflections might worry a chameleon.

Recognising ourselves in a mirror is something we take for granted. Or recognising that a glass door is a solid barrier (though drunk humans have been known to crash through glass doors!) Just because we can do this, we shouldn't assume other creatures can. Much suffering can be caused to reptiles kept in all-glass cages. Aquariums with four transparent walls are often sold as the right enclosure for reptiles.
But are they? Many lizards don't recognise that glass is a barrier and will make repeated attempts to push through it until they have injured noses. Green basilisks have a habit of just running into the glass full tilt. If you already have a four-sided aquarium  for your lizard, you must stick an opaque paper barrier on the outside of the glass in three sides. If your lizard is pushing at the glass in the front, think about doing the same for the bottom half of the glass there too.
The other problem with bog-standard aquariums is that they need a lot of extra equipment - escape-proof tops, UV lighting, arrangements for temperature gradients, etc. etc.  And they may be difficult to clean. So it is always better to buy a proper vivarium from a good reptile shop with all this built in, rather than just stick your reptile into cheap aquarium.
Chameleons have a different problem with glass. They can see their own reflection and think it is a rival. This is common with many species, even dogs and cats but these pets will generally learn to ignore reflections. Chameleons don't learn. Having a threatening rival within their enclosure is a constant worry to them. Moreover glass aquariums don't give them enough fresh air.
Tortoises feel much the same about transparent barriers. They will push like tanks against a transparent barrier whether it is glass or garden netting. If they can see a way through they will take it - somehow. They will also dig underneath it or round it. And a determined tortoise is very persistent indeed. So it is vital that any barrier is opaque, not see-through.

For snakes, a four sided glass enclosure is stressful for another reason. Snakes need hiding places - one in a hot area and a second one in a cool area. If they don't have them, they get very stressed. And chronic stress may mean they don't eat, or they get a respiratory disease.

*The human-reptile relationship - please help research by doing my survey at https://www.surveymonkey.co.uk/r/FGJZKLT

Sex and the single snake - who needs males?

From Wikipedia

Female reptiles don't always need to mate with males to have offspring. Snakes, Komodo dragons, and lizards have all given birth without sex. These have been females that were kept in zoos, labs or homes, and for some time people thought that parthenogenesis, the scientific name for virgin births, was the just effect of captivity.
But did this happen in the wild? It was difficult to know because some females reptiles can store male sperm for months or years, presumably waiting for a good time to be pregnant, ie a time when there is plenty of food and the right environment. So just because a wild reptile seemed to give birth without mating, it wasn't necessarily so. It was just delayed ordinary conception.
Then scientists, led by Warren Booth, examined 22 litters from broad banded copperhead snakes, A. contortrix,  and 37 litters from pit vipers, A. piscivorus, all from pregnant females collected in the wild. They did a DNA analysis and concluded this was automictic parthenogenesis. This probably means that when the original reproductive cell splits into two, the two new cells merge with each other and then start reproducing themselves (if I understood the process correctly).  The parthenogenesis found in reptiles like a blind snake and some lizards who automatically practice virgin birth is different and I will blog about this later.
This means that if a female snake or lizard cannot find a mate, she can give birth anyway. Aren't reptiles fascinating?  We mammals can't do this!

For more details read: Booth, W., Smith, C., Eskridge, P. H., Hoss, S. K., Mendelson, J. R. & Schuett, G.W., (2012), 'Facultative Parthenogenesis Discovered in Wild Vertebrates', Biology Letters, doi:10.1098/rsbl.2012.0666

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Why is your snake fainting?

A Youtube video of the death feint https://www.youtube.com/watch?v=9pm6hsIDXVc

The snake you are handling or are about to handle, suddenly goes limp and faints. It looks completely dead but it isn't. This is what Darwin called "the death feint." Or playing dead - though this is far from being a game for the snake.
The modern scientific term for it is "tonic immobility." Many animals including other reptiles and rabbits faint like this.
If an animal faces intense danger then an automatic reaction kicks in. There is a huge surge of adrenaline (epinephrine) and a reaction with what is commonly known as the five "Fs" - flee, fight, freeze, faint or fool about (ie do something odd which distracts the predator). Faced with being handled, a captive snake hasn't got the option to flee or to fight a large human. So fainting is one of the options left to it.
This death feigning reaction sometimes looks like a relaxed animal and ignorant rabbit owners think the rabbit is enjoying it.  Far from it. Rabbit owners are beginning to recognise this, as should snake owners. If your snake goes limp it is in utter terror.
Fainting is a last resort for an animal faced with a dangerous predator. With luck the predator will think the snake is dead and for a moment shift it's attention elsewhere. Then the snake has a chance to escape. This may work, for instance, with predators like the domestic cat.  If you watch a cat "playing" with a living mouse, when the mouse goes immobile the cat stops play for a little while. A cat's predatory drive is turned on by movement so sometimes the cat will poke the mouse to make it move so the play can continue. Cats that catch snakes often do a similar kind of playing around.
Patrick Gregory of Kent University tested the response of grass snakes to being captured. Snakes that were held by the tail rarely fainted when first grasped. Those held by the head were more likely to feign death. The larger the snake the more likely it was to remain immobile after being released. Perhaps because bigger snakes have less to fear about remaining still. The snakes that didn't faint would usually slither away as soon at they were released.
* More info at  Gregory, P. T., (2008),  'Bluffing and waiting: Handling Effects and Post-Release Immobility in a Death-Feigning Snake (Natrix natrix)', Ethology, 114, 768-774.

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Snakes in a love tangle - inside the church

Intertwined snakes on a miserichord seat in St David's cathedral Pembrokeshire, Wales. These snakes have nodules along the spine, just as medieval dragons do. They may have been inspired what the medieval monk Bartholomaeus Anglicus writes about the love that adders have for their mates. "This slaying adder and venomous hath wit to love and affection, and loveth his mate as it were by love of wedlock, and liveth not well without company. Therefore if the one is slain, the other pursueth him that slew that other with so busy wreak and vengeance, that passeth weening. And knoweth the slayer, and reseth on him, be he in never so great company of men and of people, and busieth to slay him, and passeth all difficulties and spaces of ways, and with wreak of the said death of his mate. And is not let, ne put off, but it be by swift flight, or by waters or rivers."
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Why pythons look like boas and boas like pythons.

Black headed python - Wikipedia

It's called convergent evolution.
Different species look alike even though they are not related. Hares and rabbits look alike but they are not the same species. Boas and pythons are another example. They don't even belong to the same family. Yet some of them look just like each other - though their common ancestor was 70 million years ago.
An aquatic python has a head like an aquatic boa and a land dwelling boa has a head like a land dwelling python.  Read more here
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