Understanding Reptile Vision: Parietal Eyes – January 2014

By Jennifer Greene

In this third installment of understanding reptile vision, we’ll be discussing the parietal eye that is present in many species of lizards, and its impact on how your lizard perceives the world.  The parietal eye is often referred to as a “third eye”, and in some species of lizards you can even see the scale or spot on the top of the head where the “eye” is present.  The parietal eye in lizards is tied to their pineal gland; a gland that produces, among other hormones, melatonin – the hormone that helps you sleep at night.  The pineal gland is a fascinating organ, and one that we don’t know nearly as much about as we’d like to.  Even in humans, the functions of the pineal gland are still somewhat of a mystery, so it’s understandable that in reptiles, we struggle to understand fully what impact it has on their day to day lives.

If you have never seen a parietal eye, or are unsure of what exactly one is if you wanted to look for it, in our pet lizards it is usually a small, circular scale in the center of the top of the head.  It can be grey in color, or just a slightly different shade than the rest of the lizard.  The third eye is most pronounced in the prehistoric tuatara lizard – their third eyes have similar parts as their two main eyes, including a lens similar to a cornea.  The third eye is quite primitive, “ much more like the retina of an octopus rather than that of a vertebrate” (Schwab and O’Connor, 2005).  This eye cannot see in quite the same way as the main eyes, instead likely only detecting shapes and shadows rather than full pictures.  They are also highly sensitive to light – producing markedly different hormones based on time of day, with one study showing a system of neurons reversing their reactions based entirely on the daily photoperiod of the lizard. (Engbretson and Lent, 1976)

Older studies done on lizards to examine the purpose of their parietal eye experimented with removing the eye as well as simply covering it up.  In humans, the pineal gland is what helps control our circadian rhythm, and in lizards the combination of the third eye and pineal gland serve a similar function.  Experiments that removed the third eye from common North American fence lizards found that lizards missing their parietal eyes were more active for a longer period of time than their counterparts with intact eyes.  On the surface, this doesn’t seem like such a bad thing – why wouldn’t a reptile want to be out and active for the most amount of time?  Turns out, that’s only a good thing if you’re a mammal.  We are active as much as possible to get as much food and energy as possible.  For us, just sitting costs energy, while for reptiles, the less they move, the less energy they expend.

So, when a lizard is active for a longer period of time, but is not necessarily consuming more food, being that active becomes a hindrance, not a help.  Parietal eyes helped limit the amount of time that fence lizards were spending out basking or moving around.  In addition to the differences in activity between lizards that had parietal eyes and those that didn’t, lizards with their third eyes removed were harder to startle and scare away, with speculation in one study that “the pronounced heliothermism perhaps works antagonistically to the normal retreat reaction.”  (Stebbins, pg 35)

Not only do the parietal eyes help set a lizard’s internal clock, control hormone production, and help them determine needed activity levels – they also use their parietal eyes to navigate.  A study done with Italian wall lizards found that they used the sun to navigate through a “Morris water-maze” (click link for the wikipedia article), and by tricking their biological clock to be 6 hours faster or slower, the lizards were no longer able to reach their goal at the end of the maze.  Painting over or removing the parietal eye entirely caused the lizards to no longer be able to navigate the maze at all.  (Carnacina, 2009)

All of this just scratches the surface of what the parietal eye and, through extension, the pineal gland, are responsible for and control in a lizard’s life.  This sensitivity to light is one reason for the common recommendation to provide basking lizards with bright, white lights to bask under – you are helping your lizard to keep its biological clock ticking at the right speed.  Any diurnal lizard is particularly sensitive to light, and understanding how heavily they rely on external sources to help guide their lives will help you as a keeper provide them with a rich captive life.   This is, of course, most relevant to true lizards, such as iguanas, skinks, lacertas, bearded dragons, and other similar reptiles.  There are few, if any, lizards that are nocturnal, and in fact searching online for “nocturnal lizard species” will instead bring up the gecko family.  Geckos do not appear to have the same parietal eye as diurnal lizard species, but as we saw in the last article, that does not at all mean that their sight is less attuned to light!

For your diurnal lizards at home, please be sure to provide them with a regular day/night cycle, including a nice bright, white basking light for them to heat up under.  As studies have shown, diurnal lizards rely heavily on lighting as well as heat to determine activity levels as well as hormone levels.  Good lighting not only encourages natural behaviors, but enables your pets to thrive all the way down to a cellular level.  Lighting is vital to proper husbandry, and an integral part of any set up for diurnal lizards.  Asking for help from any experienced lizard keeper in a sick, non-feeding, constantly sleeping lizard will immediately earn you questions about your lighting set up – and is it any wonder?


Augusto Foa, Francesca Basaglia, Giulia Beltrami, Margherita Carnacina, Elisa Moretto, and Cristiano Bertolucci (June, 2009) “Orientation of lizards in a Morris water-maze: roles of the sun compass and the parietal eye”, Journal of Experimental Biology, 212 Retrived from:http://jeb.biologists.org/content/212/18/2918.short

Gustav A. Engbretson, Charles M. Lent (February 1976) “Parietal eye of the lizard: Neuronal photoresponses and feedback from the pineal gland”, Proc. Nat. Acad. Sci USA Vol 73, No 2, pp 654-657 Retrieved From: http://www.pnas.org/content/73/2/654.full.pdf

I.R. Schwab and G.R.O’Connor (March 2005) “The lonely eye”, British Journal of Opthalmology, V. 89(3), 256 Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1772576/

Robert C. Stebbins and Richard M. Eakin (February 1958), “The Role of the “Third Eye” in Reptilian Behavior, American Museum Novitates, Number 1870 Retrieved fromhttp://digitallibrary.amnh.org/dspace/bitstream/handle/2246/4659//v2/dspace/ingest/pdfSource/nov/N1870.pdf?sequence=1

Notes From The Field – July 2013

By Kevin Scott

I remember that day, and recall with delight, as I walked through the desert and took in the sight of the spring desert flowers that followed the rain, giving life and bold color to the spring desert plain. See, spring is my favorite season for herping, the locusts were buzzing and song birds were chirping, the beetles were digging their holes in the sand while the rock lizards lie in the sun as they tanned. Coyotes left evidence that they had been here, but of course they’re always the first to disappear. In search of a creature – no particular kind – just taking my chances on what I might find, I cautiously tip-toed my way through the cactus, an activity in which I have had lots of practice. After the cactus I trudged on ahead, and wandered along an old, dried riverbed.

I stopped in my tracks at the moment I saw (my jaw hanging low with exuberance and awe) the curious creature that caused much confusion, for which kind it was I could draw no conclusion. At first glance I thought it could be some amphibious creature, but it was simply much too hideous. On closer inspection I saw it had scales, some sort of carapace and two lengthy tails. Some of the scutes were partially keeled, and flipping it over is when I revealed that this creature was somewhat obscurely chelonian, but appeared somehow older… silurian, or devonian? Its digits were webbed and its neck rather long, but something was missing, and something seemed wrong. You see, it had gills on the side of its head, right behind frills that were easily spread. But lacking in water, this distant location, could hardly have produced this strange adaptation. No eyes could be seen on the primitive face, not even a remnant or residual trace of an organ deemed worthy of visual perception, for locating food and for predator detection. Small holes were presumably there for olfaction but the quantity thereof evoked an exaction of closer inspection for what they might be, for there weren’t just two, but indeed there were three! Three nostrils, a notion entirely absurd, surely not even biologists have heard of something occurring in such repetition, alas, evolution has brought it to fruition.

The anomalous creature had but seven teeth, with four on the top and then three more beneath, but their shape made it hard to discern what it ate; they were kind of roundish, though more or less straight. They couldn’t be used for herbivorous chewing but the creature was clearly not made for pursuing anything other than immobile prey, perhaps it just grabbed things that came past its way. It seemed quite content to concede submission, as though for defense it had lost its volition, so I sought to expose its purpose ulterior, and subsequently moved to inspect its posterior. The subcaudal scales were smooth and divided, however no insight was thusly provided, though it possessed two sets of quaint hemipenes, the first advantageous trait I had seen.

I’ve read of strange creatures in Carrollian fiction, but nothing like this in scientific depiction. Of all of my lectures and myriad books, I’d seen nothing bearing ridiculous looks like this beast that left but a pale question mark, it was strange as a Jabberwocky, Jub Jub or Snark. It seemed hardly a question of natural history but more of a serious supernatural mystery. For I bet even Darwin’d be slightly confused, and good old Linnaeus’d be likewise bemused in attempts at this queer critter’s classification, a fruitless endeavor with no explanation. Even Lamarck couldn’t have found a prerequisite force to give rise to something so exquisite, quirky, peculiar unusual and odd… but perhaps a creator, a maker… a god?

But I digress, let’s get back to the narrative, because what comes next is especially imperative for everyone reading this to understand, why I left this thing there in the hot desert sand. I thought “if I bring this thing back to society, it would get much attention and then cause great anxiety amongst the paleo-scientific community who’d want to dissect it with carefree impunity.”

However, it just didn’t seem well adjusted to this undisclosed desert but somehow I trusted that if it had come to make it this far, despite that its looks were extremely bizarre, it would keep on surviving, prolong its existence, with a little bit of luck and extravagant persistence.

So, live and let live’s the philosophy I followed, the lump in my throat I painfully swallowed, as I shed a tear and prepared to depart with the creature that won a small place in my heart.

The Basking Spot: Excavator Clay – July 2013

Excavator Clay

by Jennifer Greene

If you’re like me, you enjoy setting up your animals in naturalistic, beautiful enclosures with plenty of options for them to run, climb, hide, and bask throughout their enclosure.  Creating a naturalistic display is fairly easy with tropical animals, and videos and set ups of tropical displays are common throughout online forums as well as groups on Facebook or google+.  However, it is much harder to find displays of desert vivariums, or cages that are more than just the basics for desert species.  There is a great deal of stigma with using sand and other small, dry, particle substrates, particularly with species considered desert dwellers, such as bearded dragons or leopard geckos. ‘

However, you can still set up a really neat, naturalistic vivarium with considerably reduced risk of substrate ingestion using a clay substrate made by ZooMed.  Excavator Clay is not an ideal substrate for every situation, but when used correctly, it can be used to create beautiful desert landscapes that allow your lizards the ability to burrow and dig without loose substrate everywhere.

Excavator Clay is a clay substrate that hardens once it’s been mixed with water.  You can put a simple base layer down throughout your cage and have a flat, plain, natural looking flooring, or create landscapes and burrows.  I highly recommend Excavator clay for burrow desert species that thrive in extremely low humidity, and/or come from extremely sandy areas. Steppe Runners, Frog Eyed Geckos, Dune Geckos, Berber Skinks, Uromastyx, Collared Lizards, and other similar desert species all work well in cages with Excavator as the base substrate.

You’ll want to prepare to set up the cage at least a week before putting the animal(s) inside – the clay needs a good amount of time to set and dry.  Have plenty of water on hand, and mix it little by little with the clay to create a sandy paste.  Build your landscape with it, having lots of fun as you make a huge mess putting it together. I suggest sloping the clay higher towards the back of the cage to add depth and make the cage look more visually appealing, but you can build whatever shapes you’d like.

Add the start of burrows by either using cardboard tubes or balloons to leave air pockets for your reptiles to find and dig out.

Enclosure for Tibetan Frog Eyed Geckos

Build up your cage and let the clay harden for at least 2 or 3 days.  If you used a lot of water, it may take over a week to fully dry, so plan accordingly if you are waiting to pick up the future inhabitant of the cage!  I like to add a layer of sand mixed with coconut bedding for digging purposes, as the two combined are a much lighter substrate that the animal can easily dig up and move around.  The loose substrate is also easy to clean, and leaves the excavator underneath fresh.  If you do find that your pet has defecated directly on the excavator, a little water will wash off any feces and make it easy for you to pick up the dirty part.

Just because your reptiles are desert dwellers, that doesn’t mean you should neglect to provide them with humid areas while using your clay substrate.  You can put damp moss in some of the burrows you’ve set up, and just keep a few areas moist.  When you provide at least one or two damp burrows/hiding areas, the species you can keep on excavator broadens.  I have successfully raised Leopard Geckos in an excavator/sand/coconut bedding mix, and if you want a nicer cage for your pets than just a glass box with carpet on the bottom – consider using clay!

Two leopard geckos lived in this exact cage as it is for over a year!

Mealworms were offered in a dish next to the water bowl, and there were multiple moist hides.

Again, it is not a substrate that is ideal for every pet and every situation, but when used correctly you can create beautiful, naturalistic desert set ups.  Your desert reptiles will benefit from the ability to burrow and hide in a more natural way, and the reduced amount of loose substrate (due to the clay being hardened) minimizes the risk of substrate ingestion to a negligable worry.

Want to see a video on setting up Excavator Clay?  We have one that you can see here:http://youtu.be/Nzu0P-aPPbw

Blaptica dubia: Equal Opportunity Feeder – July 2013

By Jonathan Rheins

Meet the Roach

As a whole, herpetoculturists are a resourceful bunch. For decades and decades we have studied, maintained, and bred a large number of diverse species in an artificial environment.  Over the years, fore-thinking herpers of all backgrounds have scratched their collective head and struggled with all of the “what-ifs” and “maybes” of our hobby.
In addition to creative solutions regarding lighting, heating, and housing needs, we have also made great strides in the realm of nutrition. Perhaps the most important being those of the constantly evolving list of tried and tested live feeder options.
Be they crickets, mealworms, mice, or rats, there are a growing number of feeders that have become mainstream staples for those wishing to keep reptiles and amphibians as pets.
However, other options exist for even the pickiest insectivore palate. Roaches.  Yes, the scurrying, invincible, invertebrate denizens of our nightmares can actually provide an incredibly healthy and balanced diet for cold-blooded creatures of all shapes and sizes.

 It should come as no surprise to many readers, but not all roach species are our friends.  Pest species can certainly wreck havoc on the pantry and nerves of even the most liberal naturalist.  That said, even the venerable commercial cricket can just as easily outwit our human coordination and “make a run for it.”

Fortunately for us, most of the commercially available roach species are of tropical origin and simply cannot thrive in the relatively cool and dry conditions of many regions of the United States.  In the case of accidental escape, these roaches will most likely die off rather than initiate a plague of any sort.
The commercial breeding of roaches for herpeteculture use is quite new to many American keepers.  However, these misunderstood arthropods have long been commonplace feeders in European collections and in those of zoological institutions and professional breeders throughout the world.
The consensus among many reptile keepers and breeders who are in the know is that of all the roaches out there, Blaptica dubia are as close to perfect as a roach species can be.  They are easy to deal with, nutritionally sound, and absolutely irresistible to every herp they meet.

Dubia Details

Blaptica dubia is a medium sized, South American roach species belonging to the family Blaberidae.  All genera within this family are ovoviviparous.  In cases of ovoviviparity, fertilized eggsacs known as oothicas are carried internally by the female roach until the eggs are fully developed.  Hatching takes place within the abdomen of the female, and at that time baby roaches (nymphs) emerge as fully developed miniature versions of the adults.
Within the United States, common names for B. dubia include Orange-spotted roach, Guyana-spotted roach, and most commonly, theDubia roach.  Latinized scientific names are always the most reliable system for describing any animal species. Furthermore, the use of Latin names ensures that the roaches being purchased, bred, or sold are identified in a consistent and accurate manner.
Dubia roaches are approximately 1/8 inch long at birth and measure just shy of 2 inches in length at maturity.  Adult dubia are sexually dimorphic, with males and females being easy to pick apart at a glance.  Males posses large wings that extend the length of the abdomen, while females have only small wing stubs, barely covering the “shoulder” region.
Flight among dubia roaches is very rare.  Despite being capable of hovering for short periods, this is a behavior that most keepers will never witness nor need to be overly concerned about.  Furthermore, B. dubia are poor climbers, and are nearly incapable of climbing smooth surfaces such as glass, acrylic, and plastic.
Breeding roaches for use as feeders is not a difficult endeavor, and maintaining multiple colonies is a worthwhile consideration if many herps are being maintained, or if feeder availability is locally seasonal or absent.  The details of breeding dubia roaches are beyond the scope of this article, but can be easily researched and implemented by the interested hobbyist.

Roach Motels

As with any live feeder, having a secure container to house them in until needed is highly recommended for keeping dubia roaches.  The use of a holding container allows for more roaches to be purchased at once, saving on feeder runs and shipping.  Furthermore, small roaches or nymphs can be purchased and raised up until they are the perfect size for being fed off.
While not strictly necessary, the use of a tight-fitting and well-ventilated lid is highly recommended.  There are many acceptable containers for temporarily housing dubia roaches including small glass terrariumsplastic faunarium critter keepers, and deli cups.

Substrates are not needed in dubia habitats, and using them may actually make cleaning and collection of tiny roaches more difficult. Dubia roaches have very little odor, and if attention is paid to cleanliness, ventilation, and removal of uneaten foods, there should be minimal smell associated with the roach container.
Hiding and climbing structures should be added such as cardboard toilet paper tubes, egg crates, or even vertically stacked cardboard pieces.   These will provide increased standing room for larger groups of roaches by allowing them to spread out and not smother each other.  Roaches that feel hidden and secure will thrive and grow faster than those under constant stress.
B. dubia is capable of surviving at temperatures between 70 and 95 degrees Fahrenheit, making them quite tough and adaptable.  Roaches kept at room temperature will survive and fare well, but as temperatures increase, more rapid growth will become evident.
The dubia holding container should be kept in a warm room in the home, or heated artificially if this can be done safely.  If external heat sources such as heat pads or heat cable are used, a high quality thermometer and appropriate temperature control device are recommended.
Blaptica Buffet

Feeder insects are only as healthy and wholesome as the foods they eat themselves.  Offering hungry, malnourished feeders to herps is akin to a human eating a hamburger that is nothing but an empty bun!  What’s on the inside is quite important in ensuring that a meal (roach, hamburger, or otherwise) is nutritionally well rounded.
The process of providing water and nutritious foods to future prey items is known as gutloading.  Feeders that have been gutloaded are many times more nutritious than “empty” feeders, and careful planning can allow for specific nutrients to be added or removed from the diet as needed.

There is more to gutloading roaches than just keeping them alive.

Just as with any other living creatures, they should never be deprived of food and water for any period of time.

B. dubia are opportunistic scavengers and in the wild they feed constantly on nearly any plant or animal matter they come across.

Fortunately, replicating such a diet for our feeder roaches is exceptionally simple.

After all, roaches are one of nature’s most devoted recyclers, and not very picky about their menu.  A staple diet of commercial insect gutloads such as Repashy Bug BurgerNature Zone Total Bites, or Fluker’s Orange Cubes work very well.  Supplement the diet with fresh fruits and vegetables as well as unsweetened cereals and grains.

Being the poor climbers that they are, food for dubia roaches should not be offered in feed dishes that are more than a few centimeters in height.  Rather, use a piece of paper, deli lid, or shallow dish to offer food.  Avoid placing food directly on the floor of the container in the interest of cleanliness and mold prevention.
Moisture should be provided at all times in the form of fresh produce and the use of a water replacement crystal/gel such as Nature Zone Water Bites.  These gels provide water and increase container humidity without the risk of roach drowning.
Feeding Time

Handling dubia roaches and offering them as feeders is not as complicated as one may expect.   While dubia roaches can run, they cannot jump or fly, and like mealworms, they cannot escape from smooth-sided feeding dishes.
Appropriately sized roaches can be easily shaken off of their egg crate and directly into a wide mouthed jar or even through a funnel. Appropriate powdered supplements can be added as per the traditional “shake-and-bake” method.
Feeding dishes with smooth, steep sides work very well for offering dubia roaches to mostreptile species.   Worm dishes designed specifically for use with live mealworms can also work quite well depending on the size and quantity of roaches being presented.  Some creativity and experimentation may be needed to get it just right for any given situation.
In glass enclosures, rack systems, or other roach proof reptile terrariums, dubia roaches may be dumped directly into the enclosure and allowed to picked off over time by the hungry resident.  Many reptiles, amphibians, invertebrates, and even fish will learn to eagerly snatch dubia roaches straight from the end of a pair of tongs!
Roaches may be slowed down before offering to herps that are less enthusiastic about hunting.  This can be accomplished by placing the roaches in the freezer 1 for-minute increments until the desired level of sluggishness has been achieved.  Responsibility and good judgment are musts for anyone wishing to chill their roaches.
Dubia roaches are less likely to cause unexpected harm to terrarium residents than some other feeder insects.  This is not to say that dozens of excess roaches will not cause stress or possible injury to an innocent leopard gecko.  It is however worth mentioning that a few uneaten roaches are not likely to bother most reptile pets.  Care should be taken however to avoid creating roach breeding conditions within a large, complicated terrarium.
Hit or Miss

There are many advantages to incorporating dubia roaches into the diet of captive reptiles and amphibians.  Dubia are a hardy roach species, they are unable to climb smooth surfaces, are nearly odorless, and are highly nutritious.  Furthermore, they are nearly irresistible to herps of all types.
However, despite this laundry list of qualifications, dubia are still a species of cockroach, and thus carry the heavy burden of a biased public.  After all, roaches can become household pests in many parts of the world.   It is understandable then for newcomers to question bringing roaches of any type into their homes.
Overall, and with basic attention to detail, dubia roaches really do make excellent feeders.  They are readily available, reasonably priced, and perhaps best of all, no one will be kept awake all night by their insistent chirps!
Dubia roaches pose little threat of escape or domestic infestation.  They are just as easy to handle and manage as any other invertebrate feeder, and properly kept dubia roaches will have no objectionable odor.
In Closing
Dubia roaches are rapidly encroaching on the fringe of what dictates a “normal feeder.”  While they are new to the scene, and unfamiliar to many, they hold a tremendous amount of promise as an easy, readily available food source for animals of all sorts.
Herps love them, as do tarantulas, scorpions, and fish.  Even picky eaters will jump upon the opportunity to have their dubia fill.  Feeder roaches may not be for every keeper or every herp.  But given the proper circumstances, dubia roaches could easily prove to be among the most perfect feeders.

Keeping Androctonus sp. in Captivity – July 2013

By Anthony Neubauer

Androctonus is the genus that contains the commonly called Fat Tail Scorpions. As the name suggests, these scorpions have an enlarged tail that allows them to possess more of their already toxic venom. They are recognized as some of the world’s most dangerous scorpions, and this should be kept in mind when choosing housing and while performing cage maintenance. The two most commonly available species in the U.S. hobby are the Yellow Fat Tail, Androctonus australis, and the Black Fat Tail, Androctonus bicolor. The care for each one is nearly identical as they are both naturally found throughout Africa and the Middle East.

Scorpions naturally have a slow metabolism, as they spend much of their time in burrows and under rocks. Because of this, they don’t require too large of an enclosure. However, they love to burrow and rearrange their cage, so one that allows burrowing is preferred. A cage size similar to a 5-10 gallon tank will be plenty large enough. The 12x12x12 glass reptile tanks offered by Exo Terra and Zoo Med make perfect and secure environments for these scorpions, as a lock can be purchased for added security. Since they are a desert dwelling species, a substrate that is dry and does not retain humidity is a must. I personally use a half-and-half mix of Zoo Med ReptiSand and Excavator clay. This allows your scorpions to dig and burrow as they would in the wild. Sand can also be used by itself, though you will want to offer more places to hide, such as flat rocks and wood. As for temperature, 75-80 degrees Fahrenheit is ideal. This can be achieved by placing a low wattage heat lamp on top, or a heat pad stuck to the side.  No special lighting is required as scorpions are nocturnal. They should be offered one or two appropriately sized crickets or roaches per week. A small water bowl can be offered, or the cage can be sprayed very lightly once or twice a month. They don’t require a lot of water because they get most of it from their food.

All in all, they are an easy-to-keep pet that doesn’t require daily care. If provided with a red nightlight, they can be seen throughout the night digging and rearranging their decor. However, they are a highly venomous animal that should be treated with respect. Their toxicity matched with their defensive personalities makes them a species that should only be kept by the more advanced and responsible hobbyist. Long tongs or hemostats should be purchased for performing maintenance, and under no circumstance should they be handled. If you’ve owned a lot of other scorpions and are ready to take it to the next level, then the Androctonus genus may be a good addition to your collection.

What to Expect When You’re Expecting: Egg Care – July 2013

By Erin Lane

What to Expect

In the May issue of the Reptile Times we discussed maternal care of gravid bearded dragons, from conception to laying.  With any luck, your breeding endeavors have so far been fruitful, and you are preparing for a clutch of eggs.  While incubation requires the least amount of action on your part, it can in some ways be the most nail-biting aspect of breeding reptiles.  In this issue, we’ll try and relieve some of those worries by going over some tips and techniques that will help those of you first time dragon breeders.  Luckily, incubating beardie eggs is about as easy as using an Easy Bake Oven.  If you follow a few simple instructions, you should be on your way to whipping up a batch of dragons.

Egg Deposition

Cupping the clutch

A simple, yet important, aspect of incubation is what to put the eggs in.  A lot of it depends on the size of the clutch and the size of the incubator.  If you only have one dragon’s eggs to worry about, a smaller incubator and smaller containers are probably the easiest.  Deli cups—those with pre-punched holes—are readily available, and easy to use.  The 8 oz cups that come in the incubator specials (described later) are perfect for dragon eggs.  I have found that you can easily fit 5-6 into each deli cup.

Larger deli cups or other ventilated containers can also be used if you prefer to put all of your eggs in one container.  This is sometimes helpful if you have more than one female.  You can then put each clutch in its own container without having to worry about keeping track of multiple smaller cups.  Regardless of which type of receptacle you choose, remember that proper labeling is important.  It’s easy to forget the lay date even when you only have one dragon’s eggs to keep track of.  I always label the container (either with a makeshift sticky tag, or directly on the lid) as soon as I get done cupping the eggs. 

Happy medium

Last time we talked about preferred medium for egg laying.  If your female is getting ready to drop eggs, having the lay box set up ahead of time is a good idea.  Anything from vermiculite to organic potting soil can be used as a substrate for egg deposition.  However, what you put the eggs in after they are laid is a little more important.  Luckily, there are a few good and easy to use options.  If you are looking for a ‘no brainer’, Hatchrite is a great option.  This incubation bedding looks a lot like perlite, but has the advantage of being ready to go right out of the bag.  Unlike other egg incubation media, Hatchrite does not require you to add water, taking out a sometimes tricky step for a new breeder.  Simply add a couple of inches of Hatchrite to your egg container, place your eggs, and leave alone until they hatch.  I have had good results with this product, and would recommend it to anyone who is a little daunted by figuring out just how much water to add to a traditional egg substrate. 


Perlite will clump, but not drip, when water to media ratio is correct.  Make finger sized impressions in the medium.

Although Hatchrite is easy to use and reasonably priced, many breeders opt for more traditional media, such as vermiculite, perlite, or a mix of the two.  I have used both, and have found that they both work well.  Let’s start with vermiculite, as it is the established go to.  I have found that it works well when the water to vermiculite ratio is done right.  The usual advice is to combine 1 part water to 2 parts vermiculite.  However, I don’t think that this is always helpful, as a lot depends on the moisture content of your particular bag of vermiculite, as well as the size of the granules.  A good way to do it is to start by adding a small amount of water, mixing it in, and testing the result by seeing how well it sticks together.  Keep adding water in small quantities and mixing until you don’t have any dry sections that won’t clump.  You can then take a handful of the moist mix and squeeze it.  If more than a few drop come out, then it is probably too wet.  If you can’t squeeze any water out, you can probably add just a little bit more. 

The problem that I have run into with vermiculite is that the size of the granules can vary from batch to batch.  I have found that the more coarse, or larger, grains work better.  The finer grains tend to either get too wet or too dry.  A good egg substrate will hold onto moisture for a long period of time without being ‘wet.’  Too much water can ‘drown’ eggs and encourage mold growth, whereas too little water can lead to your eggs desiccating.  The larger grain vermiculite seems to absorb water better, and can then provide moisture for a longer period of time without being too wet. 

This year I went with perlite, and that has seemed to work well so far.  Yes, you still have to add water, but it seems to keep the humidity at a consistent level throughout incubation.  Mix it the same way you would vermiculite, keeping in mind that though it may not feel very wet or release much excess moisture when squeezed, it probably holds onto to more than the vermiculite does.  You can buy perlite at any plant nursery or garden center. 


Eggs can quickly go bad if kept too moist.

Regardless of the type of medium you use, remember that checking the substrate about once a week or every two weeks is probably a good idea, especially with your first clutch of the year.  Eggs can and do dry out, so too little moisture can be just as big of a problem as too much.  To avoid the too-wet-or-too-dry issue, I mix my substrate a little on the dry side, and then add small amounts of water to the substrate a few times throughout incubation.  I determine whether or not to add water by sticking my finger down into the corner of the substrate. 

If it feels bone dry, I gently add water with a pressure sprayer to the corners (if in a larger container) or around the edge and in between the eggs.  Avoid spraying the eggs directly, as you really don’t want them to be wet, but don’t stress if a little water does get on them.  You can always gently wipe it off with the corner of a rag or a paper towel.  Remember, it is easier to add water than it is to take it out.

Eggs that have gone bad can and will attract bugs quickly.

Placement parameters

The number of eggs you fit into your container is obviously dependent on the size of the cup or box.  As stated previously, you can decide what will work best for you.  However, how to actually go about placing the eggs in the medium can be a little confusing; different sources will tell you different things.  In my experience, whether you cover your eggs completely, or you rest them on top, they will probably all come out okay.  The easiest way, I have found, is to make an indentation of about ¾” with your index finger or thumb into the egg substrate, about ¾” apart from each other.  Place the eggs on their sides into each indentation, and leave them alone until they hatch.  Don’t worry about covering them up; just keep them about ½ way buried.  As the media dries and the eggs enlarge, they will often seem to unbury themselves.  You can go with this, or make new indentations when you add a little more water to the container. 

Many people will tell you that you need to be careful about how you place your eggs.  Many sources will say that you must place them in the same orientation that the mom laid them, and to not turn them over or you will kill the embryo—or it will drown, or die, or break it’s eventual yolk stalk.  From my experience with this species, this is relatively unimportant when moving newly laid eggs.  Eggs can be moved about and placed with little care as to up or down early on.  Because I now candle all of my eggs after being laid, I usually try and place each egg with the ‘pink spot’ up.  This pink or red spot is seen as a faint pink ring around a red dot, usually found on one of the long sides of the egg.  If you can’t see the pink circle through the shell, it can easily be seen when candled (as described below).  My advice would be to not worry so much about which side is up when they are first laid, but to be more gentle with them as they start to develop. 

After one week of incubation you can see veins beginning to develop.

Easy bake

There are a variety of incubators available, from the simple Hovabator to the advanced Exo Terra Reptile Incubator.  The incubator you choose should be dependent on a few things.  The first is size.  How many eggs are you expecting?  Do you have one lizard, or 5?  The smaller Hovabator incubator is fine for holding a few clutches at the same time, but if you are planning on more than that, it would be worth it to get a bigger incubator.  One advantage to the Hovabator is that you can order it as part of the incubator special, which gives you 5 deli cups and a bag of Hatchrite for a great price, meaning you don’t have to look around for what you need—it all comes together in one package. 

After three weeks, you can see the embryo and the network of veins in the egg.

The second consideration is the ambient temperature in your house.  Where you put your incubator becomes important here. Most incubators will only heat, not cool, meaning that your eggs can overheat more easily if kept in a room that gets hot.  If you put your incubator in the garage where the temperature can soar in the summer months, then you should probably go for the Exo Terra Reptile Incubator, which can both heat and cool to maintain the desired temp.

The third thing to think about when purchasing an incubator is ease of operation.  How much monitoring do you want to do to maintain the proper temperature?  If you plan on placing your incubator in a room where the temperature doesn’t fluctuate much, and it stays in the 70’s most of the time, then you won’t have much to worry about regardless of which one you choose.  However, if you don’t have that luxury, a higher end incubator is probably going to make the process a little easier.  While the Hovabators are effective and easy to use, you have to monitor the temperature and adjust the thermostat accordingly.  The Zoo Med ReptiBator Digital Incubator and the Exo Terra Reptile Incubator are both programmable, meaning that you set the temperature, and they will adjust to keep it stable, even when the room temperature drops or rises.  The Zoo Med ReptiBator is a good middle ground for ease of use.  While it doesn’t have a cooling mechanism to keep things from getting too warm, it otherwise gives more temperature control and also comes equipped with a humidity gauge. 

Egg in the final days before hatching

Tools of the trade

Even when using a higher end incubator, it never hurts to have a second thermometer on board.  I use the Zoo Med Digital Thermometer (with probe) in my incubator to watch the temperature.  This is especially useful if you have an Hovabator, so that you don’t have to open the lid to check the temp.  You just insert the probe into one of the ventilation holes, and keep the unit resting on top of the incubator.

Another consideration is to use an external thermostat in your incubator.  If you already have an Hovabator or equivalent, which lacks the more precise temperature control of the higher end models, you can always set up an external thermostat to control the temp.  This is really more of a safe guard as the Hovabators usually work well as is, assuming that you keep them in a room with a moderately stable temperature.  This isn’t necessarily more beneficial from a cost perspective, but simply another way to go about regulating the temperature for your eggs.

Egg just beginning to dimple before hatching

Temps and times

Dragon eggs are fairly easy to incubate in that they can withstand a fair amount of range when it comes to temperature.  I always shoot for 84 F throughout incubation, but slightly lower or higher temps have resulted in perfectly healthy hatchlings.  There is some anecdotal evidence that eggs incubated at room temperature and those incubated hot (let’s say around 90 F and above) result in lower hatch rates and, sometimes, weak babies.  I have always incubated mine in the low to mid 80s with success, so have not strayed from that recipe yet. 

Clutch of eggs hatchinh

Just like when you are baking a cake, the temperature of your oven will determine how long you need to keep it in.  If your incubator is set to 85 F, your eggs will likely hatch faster than those set at 81 F.  A few degrees can make a difference of a week or more in some cases.  If you are incubating in the mid 80s, you can probably expect your eggs to hatch between 60 and 70 days, plus or minus a week.  Last year, at a relatively steady 84 F, my clutches went an average of 72 days before hatching.  A good idea is to start checking for hatchlings every day starting at around day 50 or 55.  While babies can stay in the incubator (and is often a good practice) for a day or two, you will want to be on top of it, and keep track of when they hatch.

Proof in the pudding

All of this information is helpful only if you have a healthy clutch of fertilized eggs.  It is possible for unmated females to lay unfertilized eggs, just as it is possible for seemingly healthy mated females to lay bad ones.  You never know until they are laid, and even then, you might have to wait and see.  I have incubated fresh, seemingly good eggs only to have them go bad sometime during the incubation process.  It can be heartbreaking, but these things do unfortunately happen.  Even when you have done everything right, you can still wind up with eggs that don’t make it.  Remember, in the wild, hatch rates are likely significantly lower than in captivity—not all eggs (or hatchlings) are destined to make it.  That’s why females lay multiple eggs, and usually multiple clutches. 

There are a few things that you can do to determine if your eggs are good, and even worth incubating.  Let me start by saying that I am incredibly optimistic when it comes to bad eggs.  Even when I suspect an egg will not make it, I will give it a chance until it is extremely evident that it’s no good.  This is especially true for newly laid eggs.  You will often times have one or two that aren’t plump and seem to be lacking filling.  Bearded dragon eggs, like those of manyreptiles, have a soft shell, which is designed to swell as the egg absorbs moisture from its surroundings, and as the embryo grows.  A ‘squishy’ egg will sometimes plump up after a day or two in moist incubation bedding, so I would always give it a chance—you might be surprised.  

Egg that has just pipped

Shell texture can also tell you a lot about whether or not an egg is good.  A good egg will typically not only feel plump between your fingers, but will have a relatively smooth dry feel to it (a reasonable time after being laid, that is).  If the egg feels slimy or slick more than an hour after being laid, chances are it’s not good.  The exact reason for this is unclear to me, but it probably has to do with the calcification process.  Females often expel underdeveloped eggs when conditions aren’t right (e.g. they are not fertilized, the female has an underlying infection, or she is young).  It is sometimes unclear what causes this to happen, but when it does, it never hurts to give the eggs a chance. 

Egg color can also be a giveaway that something isn’t quite right.  Eggs that appear very yellow usually aren’t good.  This can also be a sign that they have dried out.  Mold can also  be a sign that the egg is bad, though not in all cases.  Although I am loathe to throw out an otherwise good looking egg just because of a little mildew spot, an egg that is covered in it probably has something wrong with it.  I would recommend not throwing the egg out unless it starts to collapse.  While eggs will start to dimple just prior to hatching, or collapse when too dry, a bad egg will often collapse when others around it look fine.  Mold is usually the first sign that there is a problem with the egg, but it may also be that you are keeping the substrate too wet.  If this happens, try drying things out a bit, and see if it clears up.  If it doesn’t, but it otherwise looks okay, leave it alone—it might come out just fine.  That being said, the shell of a healthy egg should be mostly white.  You can sometimes see a pink spot or circle where the egg is beginning to vascularize, and the embryo is developing.  Healthy eggs will also usually have a soft pink glow when a light is placed next to them. 

The same egg a few minutes later – you can see the slit where the baby will emerge! 

If you have given a bad egg a shot, or a good egg has gone bad, it is best to remove it from the incubator sooner rather than later.  They can go from a little ugly to really bad in a hurry, which will attract insects or provide an opportunity for mold to grow.  Although a bad egg will usually not impact the healthy eggs around it, it is better not to let it go.  If you have an egg that you suspect isn’t going to make it, check on it every couple of days, or move it to its own container.

Hold a candle up

I have found that candling the eggs is a fun and fascinating way to pass the time until they hatch.  While I don’t recommend doing this every day, candling an egg or two from the clutch once a week doesn’t seem to cause any harm.  Again, you will read that doing so can kill the embryo, and to not candle any egg that is within a few weeks of hatching.  I disagree with this, though I will say to be gentle and proceed with caution in the later stages of incubation. 

The baby beardie emerging.

When candling, any small flashlight should do.  LED lights might be a better option since they put out bright light without much heat.  Gently hold the egg by its ends, and hold over the flashlight.  Early in development you will see the egg begin to vascularize, and the tiny embryo begin to grow.  As the embryo develops it will be harder to see what is going on in there since its body will obscure much of the light.  A few weeks out from hatching, you can often see the shadow of a tail along the side if the egg, and notice small movements.  When handling eggs this far along, I would here say that placing it back in the same position may be more important.  Will it kill the embryo to place it upside down? Probably not, but sometimes it’s best to be a little cautious. 

Time’s up

When your eggs finally get ready to hatch, you may notice a few things start to change in their appearance and turgidity.  Eggs will often start to dimple when hatching is imminent, so don’t be too concerned if this happens.  However, they do not always dimple.  I have found that when kept a little more humid, dragon eggs will often not dimple at all.  You may also notice that the eggs start to ‘sweat.’  If this is happening before you are expecting your first hatchlings, then you may need to dry things out a little by keeping the lid off of the egg container for a day.  However, if you notice this on late-term eggs, you can probably expect them to pip within a day.

Eggs that are about to hatch will also get a little softer feeling, almost as if they are full of water.  Again, be gentle with eggs that are about to hatch.  While beardies are pretty sturdy, it is probably better to be careful.  Once the egg has pipped, the egg will look deflated.  If you wait a few minutes, you might even see a little snout poke out of the end!  Once they start to hatch, leave them alone, and let them do the work.  You aren’t doing the hatchling any favors by pulling it out of the egg the rest of the way.  It will come out when it’s ready.  Neonates can stay partially in the egg for up to 24 hours as they finish absorbing the last bit of yolk.  Leave them alone, and only take them out of the incubator when they are moving around on their own. 

The next phase

Breeding reptiles can be fun, though there are often unforeseeable challenges.  Bearded dragons are an extremely rewarding pet, and have the added advantage of being easy to breed in captivity.  Whether you planned on eggs, or had a surprise, incubation can be a simple process with the right tools and a little patience.  In many ways, it is like baking a cake.  When you start with healthy, fertilized eggs, and follow the basic recipe, you will usually end up with a rewarding end product.  In other words, when set up properly, there is every reason to look forward to a good hatch rate and lots of mouths to feed in the near future.  Next month we will go over tricks and tips to taking care of those little mouths, from feeding and watering to lighting and housing. 

Reptile Vision: Nocturnal Geckos – November 2013

By Jennifer Greene

Geckos make up an extremely large group of species, the majority of which are nocturnal or at least crepuscular – that is, active at dawn and dusk.  It is worth noting that geckos evolved from diurnal lizards, and initially had the full set of rods and cones that we discussed in last month’s issue of the Times.  However, as time went on and these diurnal lizards were active only during bright daylight hours, their rod cells began to disappear, and eventually the ancestors of geckos lost their rod cells completely.  When these lizards evolved into geckos, they began moving back into nocturnal niches in the environment, and needed to develop better nighttime vision once again.  “In response to the demands of nocturnal vision without rods, the cones of nocturnal geckos have become much larger and more light-sensitive than those of their diurnal relatives” (Roth 2009).

Refresh your memory on the color spectrum and what wavelengths match which colors.

What does that mean?  That means that geckos see at night, but they see in color.  When we see at night, we are seeing in shades of grey, as rod cells simply pick up whether or not light is present, regardless of the color of that light.  Geckos can see color at light levels that equate to dim moonlight – where we would hardly be able to see at all, much less determine color!  There are studies, for example, that show that helmeted geckos can differentiate between the color blue and the color grey at extremely low light levels.  Scientists were able to test this by dusting crickets in powder dyed either blue or grey.  Crickets dyed blue were “tasty”, or had nothing extra added, while crickets dusted in grey powder were “distasteful”, and extra salt was added to the dust.  Very, very quickly, the geckos learned the difference, and chose the blue crickets over grey crickets nearly every time.  (Roth and Kelber, 2004)

In the diagram above, you can see the test used in the study.The crickets were offered to the geckos on forceps, and the ones coated in grey were always salted.  The geckos almost always refused these crickets in favor of the tastier, non-salted blue crickets.

They made the choice of blue crickets independent of the intensity of the grey coloration on the crickets.  These tests were performed at extremely low light levels, comparable to that of a night with no moonlight, and demonstrate that the geckos were capable of color vision.

An interesting point made in the study was that the scientists varied the shades of blue and grey to match in a black and white view (so if the geckos were not using color vision, the crickets would look identical), as well as grey colors that were brighter and darker to cover UV reflection.  Why would they be concerned about UV reflection, you ask?  Another study looking at crepuscular and nocturnal illumination in regards to a particular moth found that there is enough UV reflection at night for nocturnal animals to have UV sensitive vision.  (Johnson, Kelber, et al 2005)   Geckos in particular have eyes sensitive to blue and green, which makes sense when you consider that in most habitats, the wavelengths of light being reflected most fall into that color range.  Most geckos have minimal red light sensing cones, which is what leads to the use of red light bulbs for heating nocturnal reptiles – they can, at best, see minimally when red light is used to illuminate their cage.

Instead of red, the cone cells in gecko eyes see into the UV range – UVA at least, if not into the UVB range.  When testing spectral irradiance, or the radiation of various wavelengths of light off of surfaces, UV was found to be a substantial portion of light being reflected at night.   This is due to the lower amount of visible light making it through our atmosphere, allowing for more UV radiation and non-visible light to make it through, relatively speaking.  While UV is still being reflected, it is in much lower quantities (relative to overall light being reflected) during the day.  I know, I know, it sounds confusing!  During the day, because there is so much light coming through our atmosphere, it filters out most wavelengths, and what ends up making it through is mostly the visible spectrum, with smaller quantities of other wavelengths.  At night, the light being reflected from the moon, as well as starlight, is less intense in visible light.  This allows for a wider range of other wavelengths which may reflect better to make it through our atmosphere, so while there is a smaller amount of light being reflected, a larger portion of that is not visible light, but instead ranging into the infrared and ultraviolet (UV) range.

Comparing Honey Bees (Apis mellifera), Hawkmoths (M. sctellatarum, D. elpenor, H. lineata, H. gallii) and nocturnal geckos (Tarentola chazaliae).

So, back to our friends, the nocturnal geckos.  Aside from the study on helmeted geckos and their ability to differentiate between grey and blue colored crickets, there really isn’t much in the way of studies on their sight.  They are capable of multifocality, or the ability to have multiple focal zones, while interestingly, the day gecko (top row) had only one focal zone.  The varying colors in the diagram below show how much light was passing through different parts of the pupil.  The study noted large variation between individual animals in sight, which raises an interesting question for keepers – do different geckos have varying ability to see?  Do some geckos need glasses?  That’s rhetorical, of course, but it’s an interesting thought that not all geckos see as well as others. See the study in works cited for more details on this particular study on gecko vision. (Roth, Lundstrom, et al 2009)

The limited other studies on nocturnal vision and non-mammalian animals active at night show that with a full moon, the available light spectrum is nearly identical to that of daytime colors.  Naturally, it is not as bright or as intense as midday light levels, but the range of light is similar.  However, on moonless nights, the color range shifts towards the red or infrared end of the spectrum, meaning that things visible during moonless nights would seem to be redder in tone than they would during daylight or a full moon.  But geckos can’t see red, right?  So are they blind on moonless nights?  Not quite – there are other sources of light, such as star light, as well as other reflective surfaces bouncing light off of each other, leaving enough light for the blue and green seeing geckos to still be active.

The diagram above illustrates the relative levels of different wavelengths of light at different times of day – showing that while there are lower amounts of light, the wavelengths available are still similar to that of daytime illumination.  Note the impact that light pollution has on the colors of available light – interesting to consider what our captive geckos may be experiencing with the ranges of light available to them indoors, entirely surrounded by artificial light sources.

In addition, geckos seek out light to thermoregulate, which seems counter-intuitive to what many keepers have observed with their own animals.  Yes, we can keep geckos without visible light – but one study performed on Tokay Geckos demonstrated that using visible light in addition to heat enabled them to more precisely control their body temperatures both during the day as well as night.  (Sievert and Hutchinson, 1988)  The conclusion the researchers came to was that “it appears that G. gecko is using the position of the light source as well as time of day in establishing diel  (24 hour period of time) cycles of temperature selection.”  So while geckos may not actively bask out in the open under bright, white lights, they do utilize the light source as a reference point for seeking out basking areas to reach their preferred body temperature.

Nothing here is intended to drastically change established husbandry practices of reptiles we have been keeping in captivity and breeding successfully for many years.  I do, however, hope that it encourages some thought for naturalistic enclosures, or helps those with difficult species try new things to help their geckos become established.  I feel it also highlights how little we still know about these incredible animals and their natural habitat, especially when compared to other species commonly kept in captivity. When setting up naturalistic displays, I hope you find the information here helpful in setting up basking areas, full spectrum lighting, or even whether you feel those things are needed.  There is still a lot to learn, and next month, we will be examining diurnal basking lizards.

Watch the video here! 

Works Cited/ References

Lina S.V. Roth, Linda Lunstrom, Almut Kelber, Ronald H.H. Kroger, Peter Unsbo (March 30th, 2009).  The pupils and optical systems of gecko eyes.  Journal of VisionVol. 9 no. 3, article 27 .
Retrieved from: http://www-mtl.journalofvision.org/content/9/3/27.full

Almut Kelber and Lina S.V. Roth (March 1st, 2006).  Nocturnal colour vision – not as rare as we might think, The Journal of Experimental Biology, Vol. 209 
Retrieved from: http://jeb.biologists.org/content/209/5/781.full

Beate Roll (July 2001), Gecko vision – retinal organization, foveae, and implications for binocular vision, Vision Research, Volume 41 Issue 16
Retrieved from: http://www.sciencedirect.com/science/article/pii/S0042698901000931

Lynnette M. Sievert, Victor H. Hutchinson (Sept. 1988.  Light versus Heat: Thermoregulatory Behavior in a Nocturnal Gecko Lizard (Gekko gecko), Herpetologica, Vol 44 No. 3
Retrieved from: http://www.jstor.org/stable/3892340

Lina S.V. Roth, Almut Kelber (December 2004). Nocturnal color vision in geckos, Proceedings of the Royal Society of Biological Sciences, Volume 271
Retrieved from: http://rspb.royalsocietypublishing.org/content/271/Suppl_6/S485.full.pdf+html

Carrie C. Veilleux, Molly E. Cummings (July 30th, 2012).  Nocturnal light environments and species ecology: implications for nocturnal color vision in forests, The Journal of Experimental Biology, Volume 215 
Retrieved from: http://jeb.biologists.org/content/215/23/4085.full

Sonke Johnsen, Almut Kelber, Eric Warrant, Alison M. Sweeney, Edith A. Widder, Raymond L. Lee Jr., Javier Hernandez-Andres (December 20th, 2005).  Crepuscular and nocturnal illumination and its effects on color perception by the nocturnal hawkmoth Deilephila elpenorThe Journal of Experimental Biology, Volume 209
Retrieved from: http://jeb.biologists.org/content/209/5/789.full

Can Snakes Hear? Sound Detection in Serpents – August 2013

by Jennifer Greene 
All photos by author unless otherwise noted

Can Snakes Hear?

If you keep one snake or one hundred snakes, chances are you have some opinion on whether or not your scaly friends can hear you.  Some keepers are aware that studies have shown that snakes can most certainly detect vibrations in the ground, helping them determine if there is prey or a potential predator nearby.  Snakes lack an outer ear, leading some to believe that snakes are completely deaf to airborne sounds.   While the lack of a visible external ear likely limits the snake’s ability to hear airborne sounds, they do have a system of hearing that includes an inner ear.  Their hearing system is, in its own way, both simpler and more complex than our own, and by no means is it out of the question that a snake can hear airborne sounds.   Mostreptile keepers have their own opinions and knowledge of the seeming simplicity of a snake’s hearing abilities, but the reality of their sense of hearing is that it involves a wider range of the sense than our own.  They may not be able to hear the range of audible frequencies that we can, but they can sense sound in a way that is alien to us.

Anecdotally, it is not difficult to find keepers that swear their snakes can hear them.  Walking through a reptile show and asking various reptile enthusiasts if their snakes can hear them will give you the full gamut of stories about the phenomenon.  You will hear everything from someone assuring you their snake knows its name and comes when it’s called to others, assuredly too professional and experienced for such nonsense, confidently assuring you that snakes are deaf and cannot hear a word you’re saying.

Studying snake hearing and being able to provide definitive proof one way or the other ultimately requires more than the average keeper’s call for supper or similar, haphazard and informal tests.  Older experimental methods tracked electrical activity in the brains of snakes in several families when sounds at various frequencies were played; a more recent (and less invasive) study looked at the reactions of one rattlesnake species to sounds played at various levels.  Interestingly, the older experiments show that snakes have two sensory systems that detect both sound and vibration, and note that while each system detects primarily one or the other, the range for each overlaps (Hartline 1970).

Before moving forward, a quick overview of sound and hearing may help you, the reader, to better understand how snakes are capable of hearing even without an external ear, and why it is relevant that a snake’s hearing includes both airborne sound and vibrations.  First, let’s look at sound:  sound is a pressure wave through a medium, caused by vibrations.  Everything vibrates slightly at a molecular level, however, those tiny vibrations are usually too quiet for us to hear.  What we usually perceive as sound to our ears is a sound wave within a certain frequency – a vibration happening at a certain speed through the air.

Human ears perceive sound within a specific range based on what the bones in our ears can pick up and then translate to vibrations within the deepest part of our inner ear.  The cochlea is the spiral tube within our ear, and the microscopic hairs within the cochlea pick up specific frequencies of sound – each hair correlating to a different frequency.  All of that translates to our ability to hear a wide range of audible sound, typically 20 to 20,000 hertz (the measurement of the specific frequency of a sound wave).  Snakes hear not just what we consider audible sound; their entire body acts as an organ to pick up vibrations – and their brain processes these vibrations in a similar part as audible sound, creating a sense of hearing considerably different than what we experience as mammals. (Hartline, 1970) It is not as wide as our own, but it is experienced in a much, much different way.

Continuing, if airborne sound such as speech is nothing more than vibrations in the air, it stands to reason that snakes may actually be able to hear it.  In fact, experiments show that snakes are capable of hearing airborne sound within the mid to lower ranges of normal human speech.  (Hartline 1970) While snakes are much more limited than humans and other mammals in their range of perceivable sound, they are capable of hearing sounds in the ranges of 150 Hz to 600 Hz. (Hartline 1970)

Human speech falls almost exactly within that range, even with wide variance in frequency due to age and/or gender.   Baby cries can be up to 500 Hz, while children’s voices are anywhere from 250 to 400 Hz, and men and women ranging from 125 to 200 Hz on average, respectively.  (www.ncvs.org)

With snakes having this almost alien method of picking up sound, and both of their sound detection systems overlapping in terms of detecting both airborne and physical vibrations, it makes it hard to conduct experiments to determine if snakes are not just perceiving airborne sounds but also capable of understanding and reacting to them.  A recent study has found that snakes can perceive and react to airborne sound by using a soundproof enclosure and a specially designed hanging basket to minimize vibrations from the surface.  Using the notoriously cranky Western Diamondback Rattlesnake as the test subjects, the experimenters found that 92% of the time, the snakes reacted in one or more ways to airborne sounds.  (Young and Aguiar, 2002)  Their testing methods were not able to determine if the snakes could identify the direction of the sound, but did conclusively show a reaction to purely airborne sounds.  Another study compliments this information with the observation that another crotalid species, the Saharan Sand Viper, utilizes its sense of vibration to determine the direction of an object that is causing sound, providing “evidence that snakes are capable of hearing, albeit, perhaps, in a unique sense of that term.” (Young and Morain, 2001)

All of this information culminates in the conclusive statement that YES, snakes can in fact hear airborne sounds in addition to sensing vibrations in solid objects.  Their sense of hearing, while limited in frequency, does encompass a wider range of potential stimuli to help a snake understand what is going on in its environment.  While they are not quite adapted to understand speech, the ringing of a dinnerbell, or similar acoustic triggers, they are capable of hearing that these things are taking place.  When considering if a snake’s lack of understanding that you are speaking to it makes it lacking in intelligence, do also consider that there is no reason for a snake to understand human speech.  Everything in its sensory arsenal is to identify what is happening around it, and help it to determine if there is prey, predator, or something to ignore happening around it.  A snake lives a much simpler life than the average mammal, and what they do with their complex array of senses reflects this.  Just because a snake doesn’t react to you talking doesn’t necessarily mean it didn’t hear you; chances are, it just wasn’t something the snake considered worth reacting to.

Sources/Works Cited

Young, B.A. , Aguiar, A. (June 27th, 2002) Response of western diamond back rattlesnakesCrotalus atrox to airborne sounds
The Journal of Experimental Biology, 205, 3087 – 3092

Young, B.A., Morain, M. (December 10th, 2001) The use of ground-borne vibrations for prey localization in the Saharan sand viper (Cerastes)
The Journal of Experimental Biology, 205, 661-665

Hartline, P.H. (August 18th, 1970) Physiological Basis for Detection of Sound and Vibration in Snakes
The Journal of Experimental Biology, 54, 349-371

Factors Influencing Fundamental Frequency, retrieved July 18th, 2013 fromhttp://www.ncvs.org/ncvs/tutorials/voiceprod/tutorial/influence.html

10 Questions with Philippe de Vosjoli – December 2012

Philippe de Vosjoli

By Scott Wesley

Philippe de Vosjoli is an innovator in the reptile industry, a highly respected author of most of the main care books used in the industry, a breeder and so much more as we will find out in this interview!

1. We typically start off our interviews with this same general question.  Can you tell us what got you started into reptiles, and what was your first reptile or reptile experience that got you hooked?

 From the time I was very young I always had an attraction to nature. When I was in France, a period where I spent four and half years in a Catholic boarding school, I would stop during my weekend visits to Paris to a little pet store run by a former keeper at the Jardin des Plantes. He had these large mixed species vivaria at the back of his store that housed things like leopard geckos, giant day geckos, flat rock lizards, monkey tree frogs all in the same enclosure. In other tanks he had Malagasy dwarf chameleons, carpet chameleons and other species I can’t remember. Those visits made me realize there’s a wonderful mysterious natural world to be discovered. I was hooked.

2. You wrote most of the original reptile “care” books used by almost every breeder out there today, and care information / research is always changing. Looking back – what were a few things that you maybe had written back in the day that don’t apply today or opinions have since changed on the care, products, etc?

I wouldn’t change much. I think that excess oral vitamin supplementation, particularly vitamin D3, is a problem with many species, such as chameleons, various treefrogs and geckos. I wasn’t as aware of that when I first wrote care books and it took time and experiment to figure that out. I’ve been criticized for advocating feeding any amount of animal protein to green iguanas but I still don’t believe that feeding insects to juveniles and the occasional mouse to adults is harmful. One study showed that in one area adult iguanas were significant predators of juveniles. One of the biggest problems with green iguanas and all larger reptiles is providing enough heat. A proper heat level optimizes metabolic rate which will affect growth, health, and the rate of clearing of uric acid through the kidneys.

3. Personal note from the interviewer. In college – I wrote a paper on the American Federation of Herpetoculturists (AFH) for one of my Poly Sci classes (seriously). Is this something you were glad to part ways with (meaning too much work / not enough reward), or wish it had grown to be the industry leader for lobbying our interests, and have you ever thought about bringing back another industry magazine like The Vivarium?

The AFH and the Vivarium were founded by herpetoculturists whose primary goal was to represent the accomplishments and interests of private hobbyists. It wasn’t a commercial venture and the original founders all worked for free on weekends and in the evenings to get it off the ground. We were the first to publish a nationally distributed color magazine dedicated to the keeping of amphibians and reptiles and tested the grounds for the viability of this kind of publication. We also were involved in fighting unsound restrictive legislative proposals and in developing standards for responsible care. The involvement of large corporations in the pet industry had dramatic effects on the distribution of books and magazines. We were not able to compete against these large entities. I worked part time for free for 13 years as president of the AFH and contributor to the Vivarium and put in tens of thousands of dollars to keep it going. Looking back I’m not sure the effort and the financial and personal costs were worth it. I think Reptile and Herp Nation are doing a good job at filling the herp magazine niche. Starting another herp magazine is out of the question for me.

4. How is the work coming on the New Caledonian Geckos updates – and anything really exciting or new that we can look forward to in these books?

The gargoyle gecko book is now ready to go to press. It should be available at the beginning of 2013. I also have a book co-authored with Frank Fast and Allen Repashy, The Life of Giant Geckos, in the works that focuses on the natural history, social behaviors and herpetoculture of leachianus. I presented some of this information with Allen Repashy on Gecko Symposium at the 2011 National Breeder’s Expo in Daytona, an event hosted by Exo-Terra. The talk can be seen online (http://www.exo-terra.com/en/explore/gecko_symposium_2011.php) but the book contains a wealth of additional information. Chahoua will be the next project we’ll be working on.

5. You are a leader in the captive reptile breeding world. Can you tell us a few of the species that you were the first, or one of the first to work with and breed here in the US?  Also – what species are you most proud of that you were able to produce in captivity?

I bred my first leopard geckos in 1968.  As far as I know I was the first to breed the Malagasy giant water skinks (Amphiglossus waterloti) and reveal they were a species transitional to becoming ovoviviparous. I had bred the Okinawan viper (Ovophis okinavensis) in the 70s, which is another species that is evolving toward being live-bearing. With Bob Mailloux we did several first captive breedings including Chacoan horned frogs, walking frogs (Kassina leonardi, Kassina maculata), Rana ishikawae, Chilean wide mouth frog (Caudiverbera caudiverbera) and more recently Caatinga horned frogs (Ceratophrys joazeirensis). My last cutting edge snake breeding was producing leucistic puff-faced watersnakes (Homalopsis buccata) With Frank Fast we were the first to breed crested geckos, at least in the US. That showed that unlike the museum specimens that all had pointy tail nubs, crested geckos originally hatched with well developed tails.

6. You are writing a novel as well?  Can you tell us a bit about it, and what inspired you here?

My inspiration came in part from a book I was working on with Terence McKenna before his death.  In a computer model based on information shown to him during an experience with hallucinogens in Peru, we reach an end point where life as we have known it is no more.  He speculated over the years what the end point could be and his views changed from being apocalyptic to the creation of a time machine and toward the end, a technological singularity. The singularity is the point where computing entities exceed human intelligence. As a consequence, what they do becomes no longer comprehensible to us. They are as gods. According to theorists the singularity should occur sometime between 2020 and 2030. My novel is set in this time period. There are no herps in the book but bioengineered Australian blue crayfish (a species I work with) play a mind altering role.

7. You have worked with some really amazing reptiles, and some really common ones too (like pacman frogs). What is your favorite reptile/amphibian you are currently working with (either working with new morphs, or just your favorite) and why that one?

That’s a difficult question because there are so many species I like and I don’t rank them in terms of favorites. If I were to pick one species, the giant gecko/leachianus remains the one species that continues to fascinate me and that I plan on studying and keeping until I die. The way I’m wired it’s one species to which I do not habituate. Every day working with them my mind goes “Fantastic! Fantastic!”

8. How did you come up with the name Pachyforms?  What got you into working with them, and writing best selling books about them as well?

As far as the name, having to describe this group of plants as caudiciforms and pachycauls everytime I talked about them was simply too wordy. A popular name for this group was fat plants, which I thought was too crude, so I came up with a more sophisticated version combining pachy ( which means thick) and form. I have always liked unusual animals and plants. Plants that develop unique individual forms and sculptural bodies to me are the supreme forms of plants as art. Like art most of these plants increase in value with age. After seeing people’s collections of specimen plants at shows and in their homes I couldn’t; believe that there was no printed record of these living works of art. I also realized that if people did not focus on their propagation, they would eventually become extinct, not in the wild but as natural works of art that could be experienced in human society. This was the same motivation that drove me to publish the Vivarium.

9. Can you share with us a few other “industry” people that inspired or helped you out back in the day and why/how?

Although I’ve kept and bred many species of snakes, my focus for the last thirty years has been lizards and frogs. Bob Mailloux and the late Bert Langerwerf were significant inspirations. I’ve learned a great deal from their methodologies using outdoor vivaria.  I’ve also worked with Allen Repashy on various projects. His unique and very practical way of looking at problems and developing methods for commercial herpetoculture has influenced how I keep Rhacodactylus. His diet for keeping these geckos has had a major impact on making species considered among the rarest in the trade to becoming among the most popular.

10. Can you tell me what you see as a few positives, and a few negatives in regards to the direction of thereptile industry today and why?

I don’t think the negative problems with the reptile hobby can be attributed to the industry but more to socio-cultural factors. The Internet, the media technologies and social networking are strong attractors that have drawn people toward a more anthropocentric lifestyle and is a challenge for nature oriented hobbies to survive in this new world. I think we need to find ways to integrate the hobby with the new technology. Intermediating the experience of keeping herps by integrating digital cameras and microphones in setups could be a possible course.

I also think it’s time for us to assess the future of various species , decide which ones we want to establish before a variety of factors makes them no longer available. There are so many idiotic wildlife laws (e.g., listing non native species, such as Jamaican Boas and Black Pond Turtles on the Endangered Species Act) and legislation is so influenced by politics and radical animal rights groups that I  have no faith in the people in charge.  Global warming is another factor. If the predictions of global warming and sea rise are correct then many insular species will become extinct in the future. Some species that have temperature dependent sex determination will have such gender skewed populations that they will be at risk of extinction. We need to ask ourselves are there species that are ethnozoologically valuable enough that they deserve preservation, even if it is only as self sustaining populations integrated in human society. I also think we need to create programs to encourage the general public to get involved in keeping threatened species. The general public spends several hundred millions dollars annually to keep common turtles like red-eared sliders as pets. Just think if all that money could be applied to keeping rarer, less disposable species.

Brumation Basics – December 2012

Brumation Basics

By Jonathan Rheins

All reptiles and amphibians are ectothermic; that is, the environment in which they are found dictates their body temperature.  These animals have perfected the art of altering body position and their location within their surroundings to establish an ideal body temperature.  In the terrarium, this behavior is often demonstrated by animals moving in and out of localized “basking” spots.  In nature, this amounts to where the animal chooses to position itself in relation to the sun or other source of radiant heat.
During weather extremes many ectothermic animals seek refuge from the elements either underground, deep within rock fissures, or within any other acceptably insulated space.  This behavior is known as brumation,when the period of inactivity occurs during cold weather, and aestivation, when the weather is too warm for regular activity.
For wild herps, brumation and aestivation are basically survival tactics.  These behaviors are natural adaptations that allow them to slow down their metabolism drastically and survive for extended periods when conditions are simply too unfavorable for regular activity. While reptiles are generally rather tough creatures, they also often inhabit some of the harshest environments on Earth.
Central Asian (aka Russian) tortoises, Agrionemys horsfieldii,serve as a prime example of these principles.  During the winter months in most of their range temperatures can drop far below 0 degrees F with many feet of snow covering the ground.  Conversely, in the summer months, the temperature regularly soars over 100 degrees F.  When the weather reaches these extremes, A. Horsfeidii will be burrowed as far as 6’ under ground, and emerge only for 3 to 4 months after winter to eat, breed, and lay eggs.
When maintaining reptiles in a terrarium setting, we must keep in mind that the activity of many herps is seasonally dictated.   This is part of their hard-wired instinct and it is much easier to embrace this fact than try to combat it by “tricking” an animal by manipulating lighting and heating.  By gaining a thorough understanding of an animal’s natural history and behavioral patterns, it becomes easier to interpret their behavior and adjust husbandry accordingly.
There are two general approaches to dealing with brumation behavior in the terrarium setting.  With species that undergo a true brumation in the wild, it may be acceptable to replicate this rest period for captive animals housed indoors.  Animals such as tortoises and box turtles that live outside may be allowed to enter brumation on their own, with minimal involvement on the part of the keeper.  For some species, such as cornsnakes, this annual fluctuation of temperature and photoperiod induces breeding and subsequent egg-laying.  In the wild, most temperate and sub-tropical herps reproduce during the spring and summer months, ensuring the young have ample time and resources prior to facing their first winter.
If captive propagation is not your goal, most pet reptiles can be kept awake year-round.  This alternative is the more typical approach, and requires fewer changes to the husbandry routine.  In these cases, photoperiod and temperatures are mainatained the same throughout the year.  However, it should be noted that even if no adjustments are made on your part, some animals will experience a “slow down” exemplified by inactivity and decreased appetite.
A thorough understanding of an animal’s natural range and the weather patterns therein can aid greatly in making brumation preparations for any herp.  Every attempt should be made to replicate the natural environment as much as possible.  The specifics regarding brumation timing and procedures will vary from one species to another, but some generalizations can be made.
Changes in lighting and heating regimens should be done gradually, as they occur in the wild.  Transitioning areptile from “normal” summer temperatures to winter temperatures overnight can be not only stressful to thereptile, but can have negative health implications as well.  Additionally, feeding should be slowly reduced as the temperatures are decreased.  Brumating herps do not hunt or eat in the wild, and having an empty digestive tract prior to entering brumation will ensure that no undigested food is left to decay in the gut and potentially cause illness.
In the spring, this procedure is essentially reversed; temperatures and photoperiod are gradually increased and feeding is resumed once all environmental conditions are stabilized.  For many reptile species this return to warmer temperatures and longer day length triggers courtship and breeding behavior.  The actual cooling process plays a significant role as well, specifically with spermatogenesis and ovulation in male and female herps respectively.
Only animals in ideal health and of good body weight should be considered for any sort of artificial or natural brumation.  Typically, herps eat and grow during the spring and summer in preparation for cooler months when food is scarce.  Although baby herps do brumate in the wild, it is out of necessity.  Most hobbyists and breeders wait until an animal is in its second or third year prior to allowing it to undergo a full winter cool-down.
As one of the most popular and prevalent pet lizards in the US, it seems only fitting that we look at the details of brumation in bearded dragons, and its implications for the average keeper.  Many first time bearded dragon owners become understandably alarmed when their normally ravenous dragon suddenly begins sleeping all day and losing interest in food. However, the vast majority of mature dragons will show marked changes in behavior during different parts of the year.
In the United States, most bearded dragons that have reached sexual maturity (typically 12-18 months) will begin to show signs of impending winter dormancy beginning in mid-fall.  In southern California, where the author lives and breeds bearded dragons, animals begin slowing down by the end of September.  External cues such as shortened day length, lower temperatures, and fluctuations in barometric pressure all contribute to the onset of brumation in bearded dragons.
During this transitional time, most dragons will still enthusiastically eat their favorite foods, but may lose interest in less appealing fare. Basking behavior will often change as well, with animals spending less timeunderneath heat sources and more time in the cooler regions of the enclosure.
By mid-November most male bearded dragons will have stopped eating almost completely.  Female dragons tend to brumate as well, but males are more likely to exhibit more drastic changes in behavior.  Food should still be offered on a semi-regular basis as per the interest in food shown by the animal.
As the days continue to get shorter, and nighttime temperatures drop, one should not be alarmed to see their bearded dragon go for weeks, sometimes months, without eating.  Animals that are going through a normal brumation period will lose minimal body weight, and at no point should they appear skinny or weak.  However, it is normal for them to remain hunkered down in a cold and dark corner of the cage for days on end.
It is important to ensure that brumating herps, bearded dragons included, remain properly hydrated.  The majority of their normal water intake is via the foods that they eat.  So when they are off food for the winter, a water bowl should always be available.  Alternately, adult dragons can be given a 10-minute soak in warm water once or twice a week to allow ample opportunity to drink.
Most of the author’s adult dragons begin “waking up” around the beginning of March.  As the ambient temperature begins to increase and the days begin getting longer again, the dragons will begin basking more often, and showing a gradually increasing interest in food.  By April, male bearded dragons will begin displaying their full breeding behavior.  Darkened beards, head bobbing, and courting of any receptive female can be expected.
When temperatures have stabilized in mid to late spring the majority of lizards will have resumed a normal feeding schedule, and should exhibit more typical basking behavior.  It should be noted that some male dragons will be less inclined to eat when they are housed with a female.  These animals will often be more concerned with breeding than with eating.
To the uninitiated, the entire brumation or aestevation process seems quite unusual, and entirely foreign.  As mammals, we find the idea of going for extended periods of time with little to no food to be alarming, and a great cause for concern.  However, we must remember that reptiles are a very ancient and well-adapted group of animals that have evolved in such a way as to survive when and where most other organisms could not.
By familiarizing yourself with the underlying biological implications of the brumation process, one can become better prepared to recognize and accommodate these behaviors in the terrarium setting.  While some concessions must be made, overall, the best results are observed when herps are allowed to follow a natural seasonal cycle.
Behavioral and physiological changes in tune with the environment are part of what make reptiles and amphibians the creatures that they are.  If we can identify and embrace these behavioral changes, rather than allow them to concern us, it will only allow us to better care for our charges, and ensure that our herps live the most natural, and comfortable life that they can.