Archive for lizards

Fascinating Animals: Tuatara

Posted in Animalia with tags , , , , , , , , , , , , , , , , on December 10, 2012 by KarenElizabeth

800px-Sphenodon_punctatus_in_Waikanae,_New_Zealand

The animal in this picture is not a lizard.

No, this isn’t some Magritte-esque ceci n’est pas une pipe kind of philosophical thing — I’ve been posting too many philosophical ramblings lately, and I’m trying to get back into posting more regular updates about not-my-personal-drama kind of things.

The animal in the above picture is called a tuatara (genus Sphenodon), and it is one of my absolute favourite animals in the world.  They are found only in New Zealand (I suspect that they may feed occasionally on hobbits), and they are incredibly ancient.  Tuatara are the only surviving members of order Rhynchocephalia, which flourished around 200 million years ago (back in the late Triassic/early Jurassic period).  This is about the time that the first mammals (some of our early ancestors, small shrew-like critters that bore little resemblance to us) were just evolving.  By that point, rhynchocephalians already looked pretty much like their modern ancestors do — check out this fossil of an extinct species from the order:

Derasmosaurus_pietraroiae

Tuatara are distantly related to modern squamates (lizards and snakes), as well as to archosaurs (the ancestors of dinosaurs and birds), which makes them very interesting to scientists — because the two groups diverged so many millions of years ago, studying tuatara may be able to tell us a lot about how modern lizards, snakes, birds, and crocodilians evolved.  Although they look similar to lizards on the outside, tuatara possess many traits that show just how ancient they are:  their brains are more similar to those of amphibians than to those of reptiles; their lungs are single-chambered and don’t have bronchial tubes; they have a remarkably well-developed ‘third eye‘ under the skin of their foreheads (something which most modern animals have lost to evolution); they have no external ear structures and their internal ears are incredibly primitive; their vertebrae resemble those of fish and amphibians rather than those of other amniotes; they have an acrodont tooth structure (their teeth are fused to the bones of their jaw rather than being separate structures); and they have sex in the same way as birds, by simply rubbing their cloacas together, because the males don’t have penises.

Unlike most cold-blooded animals, tuatara prefer cool temperatures and will actually die of heat stress if exposed to temperatures much above 80 degrees Fahrenheit for any length of time.  This adaptation to cool temperatures is likely a factor in their longevity — it’s theorized that tuatara could live to be over 200 years old in captivity (although no one knows for sure, because we haven’t been studying them long enough), and even living in the wild (with all the associated hardships and dangers) they commonly live about 80 years.  But because they live for so long, they do their living at a very slow pace:  it can take over a year for tuatara eggs to hatch, and over 30 years for a tuatara to reach its full adult size.

Like many species in New Zealand, tuatara face great risks from introduced predators.  Having lived for so many millions of years on protected islands with few natural enemies, the introduction of animals such as rats and dogs and cats has devastated tuatara populations.  Tuatara are particularly vulnerable because of their slow pace of living:  a year is a long time for eggs to remain undisturbed in a nest when there are hungry rodents about, and a female tuatara is only able to lay eggs once every 3-5 years after she has reached sexual maturity (which can take 20 years to happen).  Like most reptiles, tuatara do not protect their nests or their babies, so unprotected eggs and young are easy prey.  Tuatara are also vulnerable to the effects of global warming — not only do higher temperatures stress them out and cause harm, but their young are temperature-sex dependent:  eggs incubated at lower temperatures will hatch out female, while eggs incubated at higher temperatures will hatch out male.  As global temperatures rise, fewer and fewer females will be hatching.  So even as conservation efforts are seeing success and protection from introduced predators is becoming more stable, there is still the risk of tuatara going extinct in a grand, sad sausage party.

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Meet the Menagerie: Lord Ivan et al

Posted in Animalia with tags , , , , , , , , , , , , on February 11, 2010 by KarenElizabeth

Time to introduce you all to the first lizardy-baby to enter my life, Lord Ivan the Not-So-Terrible.  Ivan was adopted two years ago from an old high school acquaintance who couldn’t keep her two leopard geckos any more.  I took Ivan, and Kenneth took Java.  We’ve since had many other leopard geckos arrive in our lives — first Java had babies, then Kenneth rescued two more leopard geckos from a person who didn’t know how to properly care for them and was bored with them, then more babies, and, well, you get the picture.  Most of the babies have been adopted out to other homes, because we can’t possibly keep dozens of geckos around.  But we’ve still got quite a few of these friendly little guys.

That’s Ivan there.  He’s pretty normal-looking, as leopard geckos go.  A wild leopard gecko wouldn’t have such bright yellows, but the colour and pattern are pretty standard.  Leopard geckos have been popular pets for many years, now, so there have been lots of fancy colour morphs developed in captivity through selective breeding.  Just take a look at Vladimir, Kenneth’s Tremper Albino male:

Notice the brighter orange colouring, the light eyes (always a sign of an albino), the brown instead of black spots, and the more broken-up pattern on the tail.  Vlad’s colouring would be pretty useless for camouflage in the wild, so you can tell that this was a colour morph developed in captivity.  And there are even stranger things out there — check out this list of leopard gecko morphs.  Just among our little collection, we’ve got Lola, a Hypo Tangerine Carrot Tail morph; Adrasteia, a Patternless little girl with light colouration; Java, a Jungle morph with dark colouring; and Frigga, one of Lola’s babies, who we’ve decided to keep because she’s almost patternless except for a few spots on her head, and she’s got some nice white “snow” colouring.

As you can probably guess, it’s often hard to tell exactly what you’ve got.  There are a lot of trade names out there for specific genetic lines, and leos have so much variation that you can wind up with totally random, very cool-looking individuals who simply don’t fit into any established morph.  This is because leopard geckos in the wild have a lot of genetic variation from region to region, and most morphs are recessive traits.  So even breeding together two completely normal-looking individuals, you can get some totally unexpected new traits showing up in the babies.

The scientific name for leopard geckos is Eublepharis macularius, which refers to the fact that they are spotted (macularius) and to the fact that they have true eyelids (eu = true, blephar = eyelid).  Many geckos do not have eyelids, and instead rely on licking their eyes to keep them clean.  Leos are able to lick their own eyeballs, but mostly rely on their eyelids to keep their eyes clean and moist.  Since they come from desert regions such as Afghanistan, India and Pakistan, this only makes sense:  unlike many geckos, who live in humid regions and rarely encounter particulate matter that could irritate the eyes, leos live in a place where eyelids are something of a necessity.

As you can see from the photos, leos have big, fat tails (they are in fact related to the similar-looking African Fat-Tailed Gecko).  A chubby tail is a sign of a healthy and well-fed individual, and this is where the gecko stores most of its fat reserves.  Leos can drop their tails if threatened by a predator (a process called “caudal autotomy”), which is why you should never pick up a gecko by the tail.  The tail will re-grow, but a re-grown tail is never as pretty and symmetrical as the original, and until the tail has grown back the gecko is at severe risk of health problems.  Without their fat reserves, they are at great risk of malnourishment, and of course there’s always the chance of infection as the new tail starts to grow.  The risk of tail loss is why you should never keep two male geckos together — they may fight for territory, and during the fight one or both geckos could drop their tails.  You also sometimes need to be careful with housing females together, because some females are more aggressive than others.  Kenneth’s female Jungle morph, Java, is sometimes prone to aggression, and so we don’t keep her with the other girls.

Leopard geckos make excellent pets for anyone who’s just starting out in the lizard hobby, and are a good one to introduce kids to.  They’re relatively small (only growing up to about 8-10 inches long), and a 20 gallon tank is more than adequate for a single individual.  They’re also very friendly and easy to handle, especially if they’ve been handled regularly throughout their lives and are accustomed to it.  Even if they do bite (which is rare) it’s not serious, as they don’t have much in the way of teeth.  Usually it doesn’t even draw blood, even on a thin-skinned individual like me.  I’m silly enough to hand-feed them from time to time, so I have received a few accidental bites when my fingers were mistaken for tasty treats.  Ivan’s very gentle about feeding and hasn’t ever bitten me, but Lola and Jave are more competitive eaters.

Besides a 20 or 30 gallon tank, leopard geckos do need a few things to be healthy and happy.  A heating pad or heat tape beneath one end of the tank is the best way to provide a basking area, as leopard geckos absorb heat best through their bellies.  In the wild they don’t come out when the sun is high in the sky, because it would be too hot for them — they prefer to wait until the day has cooled off, and then they will lie on the still-warm sand to get their heating needs.  A temperature gradient should be provided so that the gecko can regulate its own internal temperature by moving from the hot side to the cool side of the tank — the hot side should be kept around 85 degrees Fahrenheit, and the cool side around 75.  A light on a timer to provide some sort of circadian rhythm is recommended, but, unlike many lizards, leos don’t need UVB light in order to metabolize vitamin D, so a regular bulb works just fine.  A spot to hide should be provided at each end of the tank, and at least one of these hiding spots should be a “moist hide”.  Although leos come from the desert, the humidity levels inside their burrows can get quite high, and a hide box with a high humidity level makes shedding more easy for them.  The easiest way to create a moist hide is to simply put some moss in there, and spray it regularly with water to keep it damp.

Leos are carnivores, and are best fed with a variety of insects that have been dusted with a calcium supplement.  Like many lizards, they are prone to metabolic bone disease if they’re not getting enough calcium, so supplementation is very important.  Crickets are the most commonly recommended food, but they also live quite happily on mealworms, superworms, roaches, and occasional fatty treats like silkworms and butterworms (not too many of those, though, or you can end up with an obese gecko).  In general, an adult leopard gecko only needs to be fed about four or five crickets, once or twice a week.  I also like to leave a small dish full of calcium powder in the enclosure at all times, because if they are feeling calcium deficient they will go and lick at the powder.  And of course, fresh water should be provided at all times, because even though they live in the desert, leos are healthier and happier if they can get all the water they like.

Meet the Menagerie: Ziggy

Posted in Animalia with tags , , , , , , on January 24, 2010 by KarenElizabeth

Back in the summer, a co-worker of Kenneth’s got herself a bearded dragon (Esme).  Very exciting — until she figured out that Esme was pregnant!  Fortunately, Kenneth and I had already had success breeding our leopard geckos, and had the setup required to take care of some dragon eggs.  When Esme’s eggs were laid, we brought them home and put them in the incubator.  A few months later, we had babies!  They were tiny, and there were lots of them.

We ooh’ed and awww’ed over them for a while, but we couldn’t keep them all.  So we started finding homes for them, through pet stores, friends, and Craigslist.  It took a few months, but they’re all off to other homes now — except for one.

Meet Ziggy (yes, as in Ziggy Stardust — note the pretty orange face stripes).  Ziggy’s just about 6 months old now, and eating and growing fast.  Adults get to be anywhere from 1-1/2 to 2 feet long — Zig’s just about 8 inches now, so there’s still a ways for him to go.  In captivity, beardies can potentially live up to 20 years — but usually 10-15 is a more reasonable estimate.  Unfortunately, early death is a common thing among captive reptiles, as owners (either through having bad information, or through simple laziness) do not always provide proper care for their scaly pets.  Bearded dragons need high temperatures, UV light, and a good diet in order to live a long and happy life.

Bearded dragons are native to Australia, and are omnivorous.  As juveniles they eat a much higher percentage of insects than they do of plants, but as they get older they will develop more of a taste for salad.  At present, Zig’s eating mostly roaches, mealworms and silkworms, with a few leafy greens (dusted with calcium and vitamin D3 powder) thrown into the mix.

Beardies are known for being docile and for tolerating handling very well (especially if they’ve been handled often for their entire lives and are accustomed to it).  They’re very popular pets, and most are now captive-bred instead of wild-caught.  Many different colour morphs have been developed in captivity, and there are lots of exotic trade names for these different colours and patterns.  Ziggy is hypomelanistic — meaning that he lacks the dark pigments found on wild bearded dragons, and has clear toenails instead of dark.  He also has some pretty, orange highlights on his face and back.  But he’s not nearly as bright as some of the “red dragons” that are now being bred.  Based on my research, he could probably be called a “hypo-pastel”, or perhaps a “translucent”.  However, as I mentioned before, there are endless trade names out there for different colours and patterns, and different breeders would probably call him different things.  His colours may also develop further as he gets older, and he could become more (or less) orange as he matures.

As you can see in the picture above, I’ve recently put down sand as a substrate in Ziggy’s tank.  There are mixed feelings on sand-as-substrate in the bearded dragon world.  When they are babies, it’s a bad idea to keep them on sand — especially if you’re keeping many of them in the same tank and they are competing for food.  Babies can be clumsy eaters, and might get a mouthful of sand (which can cause digestive impaction, a potentially fatal and very painful condition).  Some owners feel that there is still a risk as their dragons get older, while others dismiss the risk as extremely minimal (an adult would have to eat quite a lot of sand before impaction would occur, and they’re less clumsy about eating).  I’ve decided that Zig is old enough (and a careful enough eater) to try the experiment, but I will be watching closely during mealtimes to be sure that there’s no sand-eating going on.  If I notice any troubles, I’ll switch the sand out for ceramic tiles, which are less nice-looking and don’t offer the same opportunities for scratching and digging about, but have no risk of being accidentally ingested.

Compared to many other reptile pets, bearded dragons are relatively high-maintenance.  As babies and juveniles, they require food at least once per day (and even more when they’re very small).  As adults they still need to be fed at least every other day, and offered a good variety of insects and vegetables.  Compared to a leopard gecko, which needs only a few insects once or twice a week, or a snake, which only needs to eat every week or two, it’s a lot of upkeep.  But beardies are very active and personable, which definitely makes up for the extra work involved.  And if you’re someone like me, who likes to eat their veggies, it’s not that difficult to buy things that can be shared with the dragon.

Expect more updates on Ziggy in the future, as I’m sure he’ll continue to be a source of interest and entertainment as he gets bigger.