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?

References:

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.