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Keeping Reptiles Newsletter
 Issue 18  
September, 2005
Scientists Discover Where Snakes Lived When They Evolved into Limbless Creatures
In this Issue

The mystery of where Earth's first snakes lived as they were evolving into limbless creatures from their lizard ancestors has intrigued scientists for centuries. Now, the first study ever to analyze genes from all the living families of lizards has revealed that snakes made their debut on the land, not in the ocean. The discovery resolves a long-smoldering debate among biologists about whether snakes had a terrestrial or a marine origin roughly 150 million years ago--a debate rekindled recently by controversial research in favor of the marine hypothesis.

In a paper to be published in the 7 May 2004 issue of the Royal Society journal Biology Letters, Nicolas Vidal, a postdoctoral fellow, and S. Blair Hedges, a professor of biology at Penn State, describe how they put the two theories to the test. They collected the largest genetic data set for snakes and lizards ever used to address this question. Their collection includes two genes from 64 species representing all 19 families of living lizards and 17 of the 25 families of living snakes. Genetic material from some of the lizards was difficult to obtain because some species live only on certain small islands or in remote parts of the world. "We felt it was important to analyze genes from all the lizard groups because almost every lizard family has been suggested as being the one most closely related to snakes. If we had failed to include genes from even one of the lizard families, we could have missed getting the right answer," Hedges explains. "For the marine hypothesis to be correct, snakes must be the closest relative of the only lizards known to have lived in the ocean when snakes evolved--the giant, extinct mosasaur lizards," Vidal says. "While we can't analyze the genes of the extinct mosasaurs, we can use the genes of their closest living cousins, monitor lizards like the giant Komodo Dragon," he explains.

The team analyzed gene sequences from each of the species, using several statistical methods to determine how the species are related. "Although these genes have the same function in each species--and so, by definition, are the same gene--their structure in each species is slightly different because of mutations that have developed over time," Vidal explains. When the genetic comparisons were complete, Vidal and Hedges had a family tree showing the relationships of the species. "Our results show clearly that snakes are not closely related to monitor lizards like the giant Komodo Dragon, which are the closest living relatives of the mosasaurs--the only known marine lizard living at the time that snakes evolved," Vidal says. "Because all the other lizards at that time lived on the land, our study provides strong evidence that snakes evolved on the land, not in the ocean."

The research suggests an answer to another long-debated question: why snakes lost their limbs. Their land-based lifestyle, including burrowing underground at least some of the time, may be the reason. "Having limbs is a real problem if you need to fit through small openings underground, as anybody who has tried exploring in caves knows," Hedges says. "Your body could fit through much smaller openings if you did not have the wide shoulders and pelvis that support your limbs." The researchers note that the burrowing lifestyle of many other species, including legless lizards, is correlated with the complete loss of limbs or the evolution of very small limbs.

Reproduced from Colorado Herpetological Society Volume 31, Number 9; September, 2004 from an article originally printed in the Herp Digest, Vol.4, No.23, February 10, 2004

Leopard Gecko Care - Part II

Eublepharis macularius
By Christina Miller -

III. Housing

An enclosure for a leopard gecko can be relatively simple. This type of gecko does not require a lot of space; a 38-litre (10-gallon) aquarium could house a pair (but do not, in any size enclosure, keep males together: they will fight!). Their enclosure requires a lid, even though it's unlikely that they would escape, preferably made of screen to allow ventilation. The bottom of the enclosure should have some kind of substrate, paper towels are the easiest to maintain and most cost-efficient substrate. Although it does not necessarily look as natural or aesthetically pleasing as sand, it is definitely cheaper and easier to clean. Also, sand, if ingested bythe gecko (which is inevitable), can cause an intestinal impaction, which can kill your gecko.

The geckos will also require at least two hiding spots (more if you have more than one lizard): One dry (preferably under the heat lamp) and one partially filled with damp sphagnum moss (also known as a humidity box). These hide boxes can be as simple as large margarine tubs with holes cut in the side.

Other cage furniture, such as rocks or pieces of driftwood, isn't necessary, but they add more to explore for the gecko and visual interest to the cage. Also, most geckos seem more content with a more naturalistic and interesting set-up. Several hiding spots should be provided.

IV. Diet

Insects should make up the main part of your gecko's diet. Live crickets (gut-loaded on nutritious foods such as fruit and flake fish food) are a good staple diet, along with mealworms, silkworms and/or roaches as an occasional supplement. Avoid feeding prey items that are larger than 1/2 the lizard's head.

Wax worms and, when your lizard is big enough, pinky (newborn and hairless) mice make excellent treats for your gecko, but they should be fed very sparingly as they are high in fat.

Feed your gecko 2-4 suitably sized crickets daily until about your gecko reaches about 12cm (5") long, then feed 4-7 crickets about every two days, supplementing with other prey items as well.

Supplement the food with vitamin and mineral supplements every other feeding.

Always offer a clean, shallow water dish.

V. Heating

Leopard geckos come from a fairly warm habitat. Daytime temperatures should range from 32°C (90°F) at the hottest spot in the enclosure, and 28°C (82°F) at the cool end. At night, the warm end should not fall much below 27°C (80°F), the coolest part of the enclosure should not be cooler than 24°C (75°F). To attain these temperatures, a 40 or 60-watt incandescent light bulb may be all you need. If, however, your house gets very cold at night or during the cooler parts of the year, a secondary heat source, such as an under tank heating pad, may be necessary. "Hot rocks," "heat caves" and other electrically heated pieces of cage furniture are not suitable for use with reptiles. They are purely faulty products: They are fire hazards, their internal thermostats often fail after little usage, and lizards (accustomed to an overhead heat source, the sun) can be severely burned by the surface.

Bartlett, R.D. and Bartlett, P. 1997. Lizard Care from A to Z.
New York: Barron's Educational Series, Inc.
Dr. Gecko (Reptile Rescue, Canada). 2003.
Norman, C. 1995. "Leopard Gecko Care"

Christina has always been interested in animals, but at nine years old discovered reptiles and amphibians to be the most intriguing. For her tenth birthday she received two Gekko ulikovvski, or golden geckos. Since then, she has moved her way around the reptile and amphibian kingdoms, now owning seven herps.

Christina studies animal health (veterinary) technology at Vanier College and is in the process of writing a detailed book about the care of leopard geckos. You can find more pictures and information on Geckos and their care at Christina's website,

Feedback and Updating

A minor review of the "How to build reptile enclosures" book was completed recently and the new book is uploaded.

Those of you who have purchased the book can download this newer version and any further updates as they occur free of charge and they will open automatically. If you have lost the download details, just email me and I will send them out to you.

I have added:

- How to make sliding doors
- Better waterproofing your cage
- Making artificial trees (also added to the site at

A number of minor amendments and additions

I would appreciate any feedback, good and bad about making your own reptile cages. I am looking for information, constructive criticism and ideas. These could include things like:

- What sort of additions would you like to see made eg making vivariums, wooden cages for Iguanas, making a cage stand etc ?
- How could the reptile cages be improved further?
- What are you particularly proud of?
- What worked well for you?
- What did not work well?
- What was difficult and how you got around it
- Requests and ideas for future reptile cage plans eg "How to make a reptile cage stand"

In particular I will soon be documenting the arboreal cage building process but I do intend to review as much as possible, hopefully based on user feedback as much as anything else.

I would also appreciate any pictures you have of your cages - using my plans or otherwise (we're all in this for fun and enjoyment so share away), so we can start to build a gallery of snake, iguana and other reptile cages of different varieties. This would be particularly useful as while many people like to show their pets in photos, not many pictures show the enclosures and I know that many people are interested in seeing how others have set up their reptile cages in order to get ideas.

I believe the collective pool of knowledge and skills we have can allow these plans to improve on a continuous basis.

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In the News
Letters to the Editor

This sad story from one of our readers who is not so fortunate to live near a reliable herp supply shop.

Dear Mark,

I always look forward to receive your newsletter every month, as a future Veterinarian, I find them very interesting and educating. When I received the last one, edition 17, I was a little saddened to read the article about Snake Nutrition III. The night before I arrived at my house late at night to find my jungle carpet python (11 months old) dead in its tank!!! I found no reason for this to happen. I quickly called my cousin (he is a Zoologist and a Veterinarian) to figure out what had happened. I found out the next day after performing a necropsy, that it had been poisoned by a pair of bad frozen hoppers I fed it the Saturday before. This tragedy could have been avoided if I had followed my instinct and tossed the mice after I noticed they where not in good condition after I thawed them (their shin was coming off). I know this is not necessarily the pet shop's fault (I've bought most of my feeders there), but my own! This is an error that should have never happened and caused the death of my favorite snake.

I would like you to warn your readers, to only feed food that they would eat themselves! I know that sounds weird, but from now on I will only feed my snakes food that looks fit for me to eat. Think of it like this: would you eat the meat of a deer that spent the afternoon out in the sun after it was shot early in the morning? I don't think so!!! I tossed the rest of the frozen mice I bought from the pet shop and kept the ones that I killed and froze myself. From now on this is going to be the only methods for feeding my snakes, that way I can ensure that they are fresh (I write down the day I froze them). I contacted the pet shop and let them know of the problem. I know the task isn't easy, and I don't know anyone that can sell quality frozen feeders on the island or ship them here.

That was the first time I tried buying frozen feeders, and look what happened.

Could you recommend a reliable source from where I can order frozen feeders, I don't want this to happen again, to me or to anyone!

Thank you for your time,
Frederick Abbott

0.1 Jungle Carpet (dead)
0.1 Colombian Red Tail
0.1 Mexican Black Kingsnake
0.1 Ball Python
0.1 Gray Banded Kingsnake


Tell Us What You Think!!

We would love to hear what you think of this (or any other) issue of Keeping Reptiles.

And of course, if you have any suggestions for upcoming issues that you'd like to share with us, please send those, too!

These could include:

  • Great herp web-sites
  • Why you pet reptile is fantastic
  • Funny things that happened
  • Dumb**s things that happened (like the one in this issue)
  • Images you'd like to share.

Remember - there are lots of people who would love to hear your stories. Just e-mail me at: Reptile-Cage-Plans

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